Evaluation of the wear-resistance of DLC-coated hard-on-soft pairings for biomedical applications - Rothammer, Benedict; Neusser, Kevin; Bartz, Marcel; Wartzack, Sandro; Schubert, Andreas; Marian, Max (Wear, 2023)
Diamond-like carbon (DLC) coatings deposited on the articulating surfaces of total hip or knee arthroplasties have the potential to enhance the overall biotribological behavior and longevity. In this contribution, we employ an ultrahigh molecular weight polyethylene ball-on-three cobalt chromium or titanium alloy pin configuration lubricated by simulated body fluid to effectively carry out screening tests. Thus, the influence of the choice of the coated component (metallic and/or polymeric) as well as the differences between a higher and lower load case with non- and conventionally cross-linked polyethylene were studied. The studied coating systems featured excellent mechanical properties with a substantial enhancement of indentation hardness and elastic modulus ratios. The adhesion of the coatings as determined in modified scratch tests can be considered as very good to polymeric and as satisfactory to metallic substrates, thus confirming the potential for the use in total joint arthroplasties. Although the coatings predominantly led to an increase in friction due to the considerably higher roughness, wear was substantially reduced. While only the metallic components were mostly coated in studies reported in literature, our investigation showed that a coating of the polymer component in particular is of decisive importance for enhancing the wear performance and increasing the service life of load-bearing implants. Moreover, single sided coating results in higher wear of the uncoated counter-part. Therefore, coating systems deposited on both articulating surfaces, polymeric and metallic, should be pursued in the futur
Keywords: Bio-tribology; Joint-prostheses; Carbon-based coatings; PVD coatings; Wear testing

Evaluierung der orientierungsbezogenen Leichtbaugüte - Gruber, Georg; Wartzack, Sandro (Konstruktion, 2013)
UnivIS-Import:2015-03-09:Pub.2013.tech.FT.FT-KLMEFK.evalui_2

Evaluierung Integrativer Simulationsansätze zur Prognose des Strukturverhaltens kurzfaserverstärkter Kunststoffproben - Gruber, Georg; Wartzack, Sandro (6. Landshuter Leichtbau-Colloquium, 2013)
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.evalui

Evaluierung unterschiedlicher Theorien zur Berechnung beanspruchungsgerechter Faserorientierungen in CFK-Strukturen - Klein, Daniel; Caballero, Steffen; Wartzack, Sandro (Design for X. Beiträge zum 24. DfX-Symposium, 2013)
A Young’s Modulus of up to 100 GPa, high strength and low density are only a few features that make carbon fiber reinforced plastic (CFRP) an ideal material for lightweight constructions. But the potential of CFRP can only be exploited if the fibers are oriented correctly. It is shown in this article that a deviation of only 10° from the ideal fiber orientation leads to a decrease of nearly 40 % in relative stiffness. Furthermore analytical methods to compute the fiber orientation within lightweight structures are only appropriate for geometrically less complex structures. Therefore, two different theories to computationally determine the ideal fiber orientation within structures made of CFRP are introduced. The first one is the load path theory developed by KELLY who originally wanted to visualize load paths within structures and the other is the CAIO method which imitates the adaptive growth of trees. After a short comparison of these different theories with the help of Mohr’s circle the fiber orientation within a b-pillar is computed according to both theories and evaluated with respect to its mechanical behavior. It can be shown that in the case of the b-pillar the fiber orientation according to the CAIO method leads to higher part stiffness and a lower Puck criterion. Additionally a few negative aspects of the load path theory that occur during the design process are pointed out.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.evalui_7
Keywords: Leichtbau; Composites; Kraftfluss

Evidence for the Applicability of Musculoskeletal Human Models to Improve Outcomes of Total Hip Arthroplasty - Scherb, David; Fleischmann, Christopher; Sesselmann, Stefan; Miehling, Jörg; Wartzack, Sandro (Computer Methods, Imaging and Visualization in Biomechanics and Biomedical Engineering II, 2023)
During the preoperative planning of total hip replacements (THR) the patient’s biomechanical condition is widely neglected. The result can be a suboptimal implant selection and positioning, which may cause muscular dysfunctions, especially for revision THR. Thus, this study provides evidence in the use of musculoskeletal human models (MHM) during preoperative planning to improve postoperative outcomes. Therefore, a patient-specific MHM is placed in the pose of single leg stance. First, gluteus medius muscle activation is simulated in three adapted situations: healthy, after primary THR and after revision THR. In a second step, a parameter study with adjustable implant parameters (neck-shaft angle, femoral offset and antetorsion angle) is executed to investigate the effects on the gluteus medius activation. The gluteus medius activation of all three situations shows a remarkable increase to the status after revision THR, with a high risk of muscular impairments occurring due to muscle weakening. The parameter study demonstrates a considerable influence of the adjustable parameters not only on gluteus medius activation but also on hip joint contact force. Concluding, MHM not only allow the analysis of a patient’s individual biomechanical condition, but also improve biomechanical outcomes by enabling the simulation of different geometrical THR implant parameters during surgery planning to support the surgeon in identifying the optimal implant parameters and positioning from both the muscle function and a kinematical (bony) perspectiv

Evidence for the Applicability of Musculoskeletal Human Models to Improve Outcomes of Total Hip Arthroplasty - Scherb, David; Fleischmann, Christopher; Sesselmann, Stefan; Miehling, Jörg; Wartzack, Sandro (Computer Methods, Imaging and Visualization in Biomechanics and Biomedical Engineering II, 2023)
During the preoperative planning of total hip replacements (THR) the patient’s biomechanical condition is widely neglected. The result can be a suboptimal implant selection and positioning, which may cause muscular dysfunctions, especially for revision THR. Thus, this study provides evidence in the use of musculoskeletal human models (MHM) during preoperative planning to improve postoperative outcomes. Therefore, a patient-specific MHM is placed in the pose of single leg stance. First, gluteus medius muscle activation is simulated in three adapted situations: healthy, after primary THR and after revision THR. In a second step, a parameter study with adjustable implant parameters (neck-shaft angle, femoral offset and antetorsion angle) is executed to investigate the effects on the gluteus medius activation. The gluteus medius activation of all three situations shows a remarkable increase to the status after revision THR, with a high risk of muscular impairments occurring due to muscle weakening. The parameter study demonstrates a considerable influence of the adjustable parameters not only on gluteus medius activation but also on hip joint contact force. Concluding, MHM not only allow the analysis of a patient’s individual biomechanical condition, but also improve biomechanical outcomes by enabling the simulation of different geometrical THR implant parameters during surgery planning to support the surgeon in identifying the optimal implant parameters and positioning from both the muscle function and a kinematical (bony) perspective.
CRIS-Team WoS Importer:2022-11-18
Keywords: Musculoskeletal human models; Patient-specific modelling; Revision hip arthroplasty; Biomechanics; Fatty degeneration; Computer aided surgery

Evolution of cell cracks in PV-modules under field and laboratory conditions - Buerhop, Claudia; Wirsching, Sven; Bemm, Andreas; Pickel, Tobias; Hohmann, Philipp; Nieß, Monika; Vodermayer, Christian; Huber, Alexander; Glück, Bernhard; Mergheim, Julia; Camus, Christian; Hauch, Jens; et al. (Progress in Photovoltaics, 2017)
Damaged modules, especially with cell cracks, can be observed quite often in photovoltaicinstallations. Little knowledge exists about long‐term stability of precracked modules at real operating conditions. Previous investigations and existing standards focus on the degradation of new, defect‐free modules. This work highlights a twofold approach for life‐time study of precracked modules: (1) outdoor exposure of 54 precracked modules for 1 year and (2) artificial stressing of 20 representative precracked modules with a novel load test setup simulating snow and wind loads. The outdoor exposure reveals that at moderate weather conditions, no changes were detectable, neither in electric performance nor in EL‐images. However, the accelerated static load tests with stepwise increasing pressures point out that above a certain threshold, cracks grow. Below this threshold, formerly unseen cracks become visible at the loaded stage. In addition, modules with a smaller number of damaged cells have a stronger tendency to degrade further than modules with an already large number of cracked cells. Remarkably, the power output measured with a solar simulator after a stress test up to 2500 Pa (describing conservative proof conditions for severe snow loads according IEC 61215) remains unchanged for almost all modules.
Keywords: cracks; electroluminescence; field test; mechanically loading; performance; pre‐cracked modules

Exact analysis of the bending of wide beams by a modified elastica approach - Campanile, Lucio Flavio; Jähne, René; Hasse, Alexander (Proceedings of the Institution of Mechanical Engineers Part C-Journal of Mechanical Engineering Science, 2011)
Classical beam models do not account for partial restraint of anticlastic bending and are therefore inherently inaccurate. This article proposes a modification of the exact Bernoulli- Euler equation which allows for an exact prediction of the beam's deflection without the need of two-dimensional finite element calculations. This approach offers a substantial reduction in the computational effort, especially when coupled with a fast-solving schema like the circle-arc method. Besides the description of the new method and its validation, this article offers an insight into the somewhat disregarded topic of anticlastic bending by a short review of the published theories and a selection of representative numerical results. © Authors 2011.
Keywords: Anticlastic bending; Circle-arc method; Elastica; Non-linear beam bending

Examining Ag-Ag Direct Bonding on Chemically Coated DBC Substrates as a Pasteless Die-Attach Approach - Häußler, Felix; Schöttner, Jakob; Schubert, Johanna; Muckelbauer, Martin; Spiecker, Erdmann; Franke, Jörg (PCIM Europe digital days 2021; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, 2021)
In this paper Ag-Ag direct bonding as a pasteless high temperature die-attach technology for power electronic applications on ceramic substrates is examined as conceivable alternative to silver sintering. To this end, sputtered Ag metallization on silicon chips and chemically coated direct bonded copper (DBC) substrates were bonded with varying parameters using design of experiments. Factors were pressure, bonding time and surface treatment. For the best parameter set average die-shear strengths of 29 MPa (out of 4 samples) have been reached processing non-polished silver coated DBC substrates at 250deg C with 20 MPa pressure and 60 minutes of process time. Microsections and images from a scanning acoustic microscopy (SAM) showed connected and non-connected areas at the joining interface. Lower shear strengths were found for polished surfaces than for the non-polished counterparts. By scanning electron microscopy (SEM) analysis the diffusion-based development of solid interconnection was confirmed, demonstrating feasibility of Ag-Ag direct bonding on grinded DBCs. The overall results affirm the viability and point out challenges of this die-attach proces
Keywords: silver direct-bonding; power electronics packaging

Examining lightweight design potential of the human musculoskeletal system by using the example of an articulated arm robot - Bartz, Marcel; Brand, Henning; Bender, Beate (Book of Abstracts: 1. Symposium for Lightweight Design in Product Development, 2018)

Experimental and numerical analysis of tribological effective surfaces for forming tools in Sheet-Bulk Metal Forming - Kersting, Petra; Gröbel, Daniel; Merklein, Marion; Peter, Sieczkarek; Wernicke, Sebastian; Tekkaya, A. Erman; Krebs, Eugen; Freiburg, Dennis; Biermann, Dirk; Weikert, Tim; Tremmel, Stephan; Stangier, Dominic; et al. (Production Engineering, 2016)
Sheet-Bulk Metal Forming (SBMF) allows the manufacture of complex parts with integrated functional form elements, such as teeth and thickened areas. Therefore, bulk forming operations are applied to sheets with initial thicknesses of 2 or 3 mm. The design and functionality of the tools are as important as the process itself. Therefore, the working group “Tools” of the Transregional Collaborative Research Centre on Sheet-Bulk Metal Forming (CRC/TR73) focuses on the optimization of the technical tool design. By varying topographies or applying tailored coatings, the friction behavior is changed to achieve a better form filling and to reduce process forces during the forming operations. In this paper, the potential of different tailored surfaces is validated by simulations and experimental studies. The tribological behavior of 14 surface microstructures is evaluated using a half-space model in order to select structures suitable for application. Those were characterized experimentally by ring-compression and pin-extrusion tests. The determined friction factors were used in a forming simulation to predict the form filling of small cavities in a flow forming operation. Furthermore, special attention is paid to the utilization of the anisotropic behavior of specific structures. The results were validated by an incremental gear forming process.
Keywords: Sheet-Bulk Metal Forming; Tailored surfaces; Milling technologies; Coating technologies; Forming simulations; Tribology simulation

Experimental and Numerical Studies on Microtextured Surfaces for Sliding Point Contacts under EHL Conditions - Marian, Max; Grützmacher, Philipp; Tremmel, Stephan; Rosenkranz, Andreas; Mücklich, Frank; Wartzack, Sandro (The 18th Nordic Symposium on Tribology – NORDTRIB 2018, 2018)
Microtextures on the rubbing surfaces may influence the friction and wear performance of lubricated contacts. While this approach has already reached industrial application for sliding contacts with lower contact pressures, the effects for higher loaded EHL contacts are still topic of basic research. For this reason, geometrically defined microtextures, manufactured by a hot micro-coining process, were used for ball-on-disk experiments and characterized with regard to their friction and wear behavior. Numerical EHL simulation based on the full-system approach is applied, acting as a numerical zoom into the contact and contributing to a better understanding of the observed effects and phenomena. Particular attention is paid to the influence of geometrical parameters of microtextures regarding depth, lateral dimensions and position within the contact area. Hence, the importance of structural parameters and microtexture position regarding the tribological behavior is verified numerically and experimentally. Thus, it can be seen that deviations in those parameters can have a strong influence on lubricating conditions, possibly overcompensating beneficial effects induced by microtexturin
Keywords: Microtexturing; Elastohydrodynamic Lubrication; Micro-Coining; Lasertexturing

Experimental and simulative assessment of crashworthiness of mechanically aged short-fibre reinforced thermoplastics - Witzgall, Christian; Wartzack, Sandro (Proceedings of the International Conference on Engineering Design, ICEDVolume 1, Issue DS87-1, 2017)
Short-fibre reinforced thermoplastics (SFRT) are increasingly used in 21st century's automotive construction. Besides statically loaded parts, SFRT are also used for safety-relevant components such as door modules and crash absorbers. Temperature, chemically aggressive media as well as mechanical loading lead to aging effects within the plastic, which generally, weakens the material's mechanical properties. Thus, within the present paper, a series of tests is introduced in order to investigate the effect of mechanical ageing on the material's crashworthiness behaviour. Furthermore, a concept for consideration the effects of ageing within numerical simulation is introduced.

Experimental investigation of tool-sided surface modifications for dry deep drawing processes at the tool radii area - Krachenfels, Kim; Rothammer, Benedict; Tremmel, Stephan; Merklein, Marion (Procedia Manufacturing, 2019)
In conventional deep drawing processes lubricants are applied to reduce friction and wear. Demands for increased sustainability, environmental protection and resource efficiency motivate the realization of lubricant-free forming processes. The direct toolworkpiece contact during dry deep drawing leads to changed tribological conditions. Especially in the areas of increased normal and shear stresses, such as the die radius, the dry contact causes an increased risk of wear and damage to the sheet surface. A wellknown approach to face the challenges of dry deep drawing of steel sheets and aluminum alloys is the application of amorphous carbon based coatings on the tool surfaces. Within this study the tribological behavior of conventional and modified tool surfaces at the critical radii area is investigated with a strip bending rotation test. In this test, the friction coefficient is determined based on the relative movement between a rotating test cylinder and a sheet-metal strip bent in a die. For the tribological tests the sheet materials AA6014, AA5182 and zinc coated DC04 are applied. The modification of the tool sided surface was achieved by applying ta-C and a-C:H coatings to the test cylinder. In addition to tests with coated surfaces, tests with uncoated tools are carried out for reference. By analyzing the resulting friction coefficients for the different sheet materials, the suitability of ta-C and a-C:H coatings for dry deep drawing processes is evaluated comparatively. In order to investigate cause-effect relations as well as wear mechanisms, the tool and workpiece surfaces are characterized before and after testing.<br
Keywords: Dry Deep Drawing; Tribology; Carbon Based Coatings

Experimental investigations of lubrication mechanisms in total knee replacements - Nečas, David; Vrbka, Martin; Marian, Max; Wartzack, Sandro; Galandáková, Adéla; Gallo, Jiří; Wimmer, Markus A; Hartl, Martin (5th International Conference on BioTribology, 2021)
Introduction: Total knee arthroplasty (TKA) has become a routine procedure for patients suffering from knee osteoarthritis. Since tribological processes influence the service-life of implants, the present study is targeted to identify lubrication mechanisms occurring in the knee replacement, focusing on the role of specific synovial fluid constituents under application of realistic operating conditions. Methods: The contact of a femoral knee component articulating on a tibial plateau made of transparent polymer was observed using fluorescent microscopy. A knee simulator was used for contact analysis, while the joint was lubricated by various model synovial fluids. Prior to the main phase of testing, the contact zone was lubricated by a mineral oil, while the data were compared to those obtained by the numerical model presented in another contribution. Results: The contact zone showed considerable changes in terms of size and shape of the contact throughout the cycle. The experiments with oil showed very satisfactory agreement with numerical prediction. Subsequent tests performed with model synovial fluid enabled to design a lubrication model of TKA focusing on the role of specific synovial fluid constituents. In particular, it was found that hyaluronic acid together with phospholipids support formation of thin stable boundary layer of γ-globulin. Further enhancement of the lubricating film is attributed to increasing thickness of albumin layer being adsorbed on γ-globulin base. Discussion: The present study employed a unique experimental set-up enabling direct in-situ observation of knee replacement components allowing the actual geometry of the rubbing surfaces together with the application of transient operating conditions. Results revealed that formation of the lubricating film is substantially influenced by the applied testing fluid. Moreover, time test showed that the film exhibits decreasing tendency under continuous loading; thus, rest periods enabling film recovery are recommended in order to enhance implant longevit

Experimental Investigations of Rolling Element Bearings Exposed to Centrifugal Load at a Centripetal Acceleration up to 3 000 Times Gravity - Hochrein, David; Tremmel, Stephan; Graf-Goller, Oliver; Hahn, Bodo; Wartzack, Sandro (The 6th World Tribology Congress, 2017)
Keywords: rolling element bearing; centripetal acceleration; frictional moment

Experimental study on the tribological behavior of ceramic disks for application inmixer taps under different lubrication conditions - Ziegler, Marlene; Rothammer, Benedict; Bartz, Marcel; Wartzack, Sandro; Beau, Patrick; Patzer, Gregor; Henzler, Stephan; Marian, Max (Industrial Lubrication and Tribology, 2023)
Purpose – The evaluation of the haptics of water taps and wear-related changes during usage usually involves time- and cost-intensive testing. The purpose of this paper is to abstract the tribo-system between technical ceramic disks of water tap mixer cartridges to the model level and study the tribological behavior. Design/methodology/approach – The friction and wear behavior was studied by means of an alumina ball-on-original alumina disk setup at different temperatures as well as under dry conditions and under lubrication by different greases. Thereby, the frictional behavior was measured in situ, and the wear losses were analyzed by means of laser scanning microscopy. Findings – It was shown that friction and wear can behave in a contrasting way, whereby one grease might lead to low friction, that is, an easygoing movability of the water tap, but to increased wear losses. The latter, in turn, is an indicator for the usability and service life, which cannot be explained from friction alone. Thereby, the viscosity of the base oil, the grease consistency and additives were identified as relevant grease formulation parameters to allow for fluid film (re-)formation and removal of wear particles. Originality/value – To the authors’ best knowledge, this is the first approach to systematically analyze the friction and wear behavior of technical ceramic disks of water tap mixer cartridges in dependency on the temperature as well as the used lubricating grease. This approach is relevant for developing screening test strategies as well as for the selection of lubricants for water tap applications.<br
Keywords: Tribology; Grease; Ceramics; Wear; Friction; Water grade lubricants

Experimentelle Ermittlung von Verschleißkoeffizienten ölgeschmierter Kontakte an einem Zwei-Scheiben-Tribometer - Winkler, Andreas; Bartz, Marcel; Wartzack, Sandro (Tribologie und Schmierungstechnik, 2023)
Im Rahmen dieses Beitrags wird ein Vorgehensmodell zur experimentellen Bestimmung von Verschleißkoeffizienten mittels eines Zwei-Scheiben-Tribometers vorgestellt. Mithilfe dieses Vorgehensmodells lassen sich beliebige Slide-to-Roll Ratios (SRR) einstellen, um somit neben reinen Gleitkontakten auch Wälzkontakte abbilden zu können. Die Verschleißkoeffizienten wurden zum einen mittels taktiler Oberflächenmessung und zum anderen mittels gravimetrischer Messung berechnet. Beide Methoden weisen eine sehr gute Übereinstimmung auf. Die vorgestellten Tribometerversuche orientieren sich an einem Anwendungsbeispiel aus dem Bereich der Wälzlagertechnik. Abschließend wird die experimentell gemessene Verschleißtiefe der Prüfscheiben mit einer numerischen Verschleißsimulation abgegliche
CRIS-Team Scopus Importer:2024-12-16
Keywords: boundary lubrication; mixed lubrication; tribology; two-disc-tribometer; wear coefficient; wear modelling

Experimentelles Prüfverfahren an einem Vierlagerprüfstand zur Ermitt-lung des Reibungsmomentes einer einzelnen Angular Roller Unit unter axialer und radialer Last - Wirsching, Sven; Hierold, Patrick; Stahl, Thomas; Tremmel, Stephan; Wartzack, Sandro (61. Tribologie-Fachtagung 2020 Reibung, Schmierung und Verschleiß Forschung und praktische Anwendungen, 2020)
Different types of rolling bearing arrangements are used in gearbox applications. The load carrying capacity and fric-tional power of the rolling bearings has a significant influence on the efficiency and performance of the gear unit. A precise knowledge of the load condition of the rolling bearings can be used to reduce friction, so that energy can be saved and the performance can be optimally used. The experimental determination of the frictional torque is an im-portant component for the further development and validation of new bearing geometries. The performance of the rolling bearing must be checked over the speed and load ranges. In many cases, the bearing arrangements are not under purely axial or radial load but under combined load. Initially, only purely axial or purely radial loads can be usefully investigated on conventional two or four bearing test rigs. For this purpose, the total frictional torque of both or all four bearings is measured. Due to the symmetrical distribution of the load to the bearings, it is possible to derive the frictional torque of the individual bearing. Therefore, the evaluation of the frictional torque of the single bearing on a four-bearing test rig would be a cost-effective alternative to a single bearing test rig. This procedure is not allowed for bearings under combined load, because in the present case the outer bearings receive a combination of axial and radial force and the middle bearings the radial force. For this reason, the following paper presents an experimental test method that allows the determination of the frictional torque of a single bearing on a four-bearing test rig. In the test, the total frictional torque of all two or four bearings is measured. The outer two bearings can be loaded axially and simultaneously radially. The middle bearings transmit the radial load. In order to determine the frictional torque for the outer bearings, first, tests are executed with four purely radially loaded ball bearings. In the next step, tests are performed with the testing bearings under purely radial load. In a further step, the rolling bearings are combined so that the testing bearings are inserted at the outer positions and the ball bearings at the middle once. By evaluating the total frictional moment in the tests, the frictional moments of the individual bearings can be calculated and an error estimation is possible. Finally, this bearing arrangement is tested under a combined load condition and the frictional torque of the testing bearings is determined under consideration of the error. The results of the tests are analyzed and discussed.<br
Keywords: rolling bearing; friction; combined load; four bearing test rig; experiment

Exploring Dataset Bias and Scaling Techniques in Multi-Source Gait Biomechanics: An Explainable Machine Learning Approach - Fleischmann, Sophie; Dietz, Simon; Shanbhag, Julian; Wünsch, Annika; Nitschke, Marlies; Miehling, Jörg; Wartzack, Sandro; Leyendecker, Sigrid; Eskofier, Björn; Koelewijn, Anne (ACM Transactions on Intelligent Systems and Technology, 2024)

Exploring the importance of a usable and emotional product design from the user’s perspective - Buker, Tina; Schmitt, Teresa; Miehling, Jörg; Wartzack, Sandro (Ergonomics, 2022)
Usability and emotionality are important components of user experience. However, an equal consideration of both constructs in product design is not always possible due to sometimes competitive objectives. In order to foster a user-oriented design decision in such conflicting situations, this paper examines the general importance of both constructs and their dimensions from the user’s perspective while taking into account socio-demographic variables. Examination was realised by conducting a product independent anonymous online survey (n = 130). The findings confirm that both constructs are important, yet in a direct comparison, usability is perceived as more important than emotionality. Taking selected dimensions of both constructs into account, an intuitive, easy and learnable usage, suitability for the user's task and freedom from impairment are particularly important in terms of usability. An aesthetic and pleasurable product design as well as originality is essential in terms of emotionalit
Keywords: usability; emotional design; product design; user-centred design; empirical study

Exploring the lubrication mechanisms of synovial fluids for joint longevity – A perspective - Marian, Max; Shah, Raj; Gashi, Blerim; Zhang, Stanley; Bhavnani, Kiran; Wartzack, Sandro; Rosenkranz, Andreas (Colloids and Surfaces B: Biointerfaces, 2021)
Synovial fluids are complex fluids responsible for the exceptional lubrication present in synovial joints. These fluids consist of various constituents, including hyaluronic acid, surface-active proteins (i.e., lubricin), surface-active phospholipids, as well as various other proteins such as human serum albumin and gamma-globulin seric proteins, each of them playing an essential role in lubrication. Being the key to the most efficient biotribological systems, this article is intended to review the current understanding of the underlying lubrication mechanisms of the synovial fluids enables prospective usage in numerous applications, especially as a lubricant for hip and knee prosthetics in combatting osteoarthritis. Current research focuses on the determination of the role of proteins in prosthetic lubrication, optimal material combinations for prosthesis, and the effects of relevant physical variables in prosthetic lubrication. The characterization of prosthetic lubrication and wear mechanisms by synovial fluids represents a prominent challenge in tribological research, yet also an important hurdle to overcome towards optimal lubrication of articular prosthetic
Keywords: Biotribology; Lubrication; Synovial fluid; Synovial joint; Hip replacement; Knee replacement

Failure mechanisms of a hydrogenated amorphous carbon coating in load-scanning tests - Hetzner, Harald; Schaufler, Jens; Tremmel, Stephan; Durst, Karsten; Wartzack, Sandro (Surface & Coatings Technology, 2012)
A diamond-like carbon (DLC) coating with a top layer of pure hydrogenated amorphous carbon (a-C:H) and an interlayer of tungsten-modified hydrogenated amorphous carbon (a-C:H:W) was deposited onto polished cylindrical specimens of a hardened and tempered cold work tool steel. On a load-scanning test rig, tribological-mechanical tests under dry conditions with DLC coated specimens sliding against identical, but uncoated specimens were performed. Additionally, comparative tests with DLC sliding against DLC and tool steel sliding against tool steel were carried out. During each test cycle, the normal load was gradually increased from 13 to 350. N, corresponding to a Hertzian contact pressure of 1.0 to 3.0. GPa. The coefficient of friction was monitored as a function of the normal load, with a significant increase in friction indicating failure of the coating. The tests were repeated and stopped at different total numbers of load cycles. After the tests, a FIB-assisted microscopical analysis in terms of wear and damage of the DLC coating was performed, revealing the (subsurface) failure mechanisms. For DLC sliding against steel, the coating fails within only few load cycles; first tribologically and after that mechanically. Failure is initiated by adherence and subsequent transfer of steel of the counter body. Below adhered steel flakes, tensile cracks form in the a-C:H top layer, with sharp crack edges removing even more steel from the counter body. In following load cycles, coating fragments are being pulled out at these spots, representing the final failure mode. In contrast, for DLC sliding against DLC, no coating failure and also no significant wear are observed, even after a considerably higher number of load cycles. © 2012 Elsevier B.
UnivIS-Import:2015-03-09:Pub.2012.tech.FT.FT-KLMEFK.failur
Keywords: a-C:H; Coating failure; Diamond-like carbon; Load-scanning test

Failure mechanisms of a tungsten-modified hydrogenated amorphous carbon coating in load-scanning tests - Hetzner, Harald; Schaufler, Jens; Tremmel, Stephan; Durst, Karsten; Wartzack, Sandro (Surface & Coatings Technology, 2012)
Polished cylindrical specimens of a hardened and tempered cold work steel were coated with a tungsten-modified hydrogenated amorphous carbon coating (a-C:H:W). On a load-scanning test rig, tribological-mechanical tests under dry conditions with coated specimens sliding against identical, but uncoated specimens were performed. Additionally, comparative tests with a-C:H:W coated specimens sliding against a-C:H:W coated specimens were carried out. During each test cycle, the normal load was gradually increased from 13 to 350. N (Hertzian contact pressure of 1.0 to 3.0. GPa). The coefficient of friction was monitored as a function of the normal load, with a significant increase in friction indicating failure of the coating. These tests were repeated and stopped at different total numbers of load cycles. After the tests, a FIB-assisted microscopical analysis in terms of wear and damage of the coating was performed, revealing the (subsurface) failure mechanisms. The results obtained show that at Hertzian pressures of more than 2. GPa and after about eight load cycles, failure of the a-C:H:W coating is initiated by locally accumulated adhesion of steel flakes, repeatedly occurring at random contact pressures in this load range. The adherence of steel goes along with a local increase in friction, inducing the formation of small shear cracks in the coating top layer. Continued crack formation finally results in partial delamination of coating material and disruption of the surface, in affected areas only. Reference tests with the pairing a-C:H:W/a-C:H:W underline that, very much unlike pure hydrogenated amorphous carbon (a-C:H), a-C:H:W is a rather ductile material with the ability to stick to itself. A discussion of this study's results against the background of a similarly conducted previous study of an a-C:H-based coating system reveals some similarities, but also significant differences in the tribological and mechanical behaviour of both types of amorphous carbon. © 2012 Elsevier B.
UnivIS-Import:2015-03-09:Pub.2012.tech.FT.FT-KLMEFK.failur_1
Keywords: a-C:H:W; Coating failure; Diamond-like carbon; Load-scanning test

Fatigue Behaviour and Its Effect on the Residual Strength of Long-Fibre-Reinforced Thermoplastic PP LGF30 - Witzgall, Christian; Gadinger, Marc; Wartzack, Sandro (Materials, 2023)
It is undeniable that mechanical properties, such as the stiffness or residual strength of fibre-reinforced thermoplastics, are adversely affected by fatigue damage caused by cyclic loading. In order to quantify and predict this damage influence, a calculation approach was developed in the past for the subgroup of short-fibre-reinforced thermoplastics. In order to test and expand the applicability of this approach to the field of long-fibre-reinforced thermoplastics, the decrease in mechanical properties is investigated experimentally in this paper using PP LGF30, propylene reinforced with long glass fibres, as an example. The paper describes both the fatigue behaviour and the residual strength of the material after fatigue damage. A decrease in the residual strength of up to about 35% could be recorded. The paper also presents a modelling approach that predicts the orientation-dependent fatigue strength of the material, and furthermore allows for the calculation of its residual strength as a function of fatigue damage. The novelty of the contribution lies in the continuous modelling of fatigue behaviour for arbitrary oriented samples of long-fibre-reinforced thermoplastics and also in the prediction of its residual strength depending on previously induced fatigue damage. <br
Keywords: fatigue; residual strength; long-fibre-reinforced plastics; PP LGF30; material data

Fatigue Damage of Short Fibre-Reinforced Thermoplastics in Crashworthiness Simulation - Witzgall, Christian; Wartzack, Sandro (Applied Mechanics, 2023)
Service loads repeatedly stress components on a regular basis and lead to fatigue damage in the material. In the case of components made of short fibre-reinforced thermoplastics, which are also crash-relevant in addition to only bearing service loads, however, a significant deterioration in mechanical properties can be observed after fatigue damage has been introduced. This is where the approach presented in this paper comes in: in order to enable a realistic simulation of such components in their used conditions, the material data are assigned depending on previously determined damage. The approach, which combines the domains of highly dynamic and cyclic experiments as well as different types of numerical simulations, is tested for its performance in the present paper. For this purpose, component tests are carried out on cross-rib beams, which serve to validate the method. The novelty and uniqueness of this paper lies in the linking of fatigue life and crashworthiness considerations for short fibre-reinforced thermoplastics, which, in this case, is raised to a new level by considering the component level for the first time.<br
Keywords: fatigue; crashworthiness; short fibre-reinforced plastics; PBT GF30; component testing

FEA-Assistenzsystem – Plausibilitätsprüfung für Finite-Elemente-Simulationen mittels sphärischer Detektorflächen - Sprügel, Tobias; Kestel, Philipp; Wartzack, Sandro (Beiträge zum 27. DfX-Symposium, 2016)
Finite Element Analysis (FEA) is a very efficient tool for optimizing product performance and quality. Hence, more simulation engineers with a lot of experience are needed, but they are not available. Consequently other users, such as design engineers, should be able to perform valid, reliable FEA. One of the goals of the research cooperation FORPRO² is to create a knowledgebased FEA assistance system with an integrated plausibility check for structural mechanics. Within this paper a methodology for a plausibility check using spherical detector surfaces is presented. Thereby it is possible to reduce any FE simulation to matrices of fixed size for each boundary condition and each FEA result variable. The created matrices can then be combined to form a single larger image. These images can afterwards be classified as plausible or implausible by a Deep Learning Neural Network.

Feature-based approach for the automated setup of accurate, design-accompanying Finite Element Analyses - Kestel, Philipp; Schneyer, Thomas; Wartzack, Sandro (Proceedings of the 14th International Design Conference, 2016)
Finite element analyses (FEA) gain huge attention in engineering design practice. However, an efficient use of FEA requires early application in the product development process. Furthermore, extensive specialist knowledge is a crucial prerequisite to perform reliable simulations. Due to time constraints, design accompanying FEA are performed too rarely by experienced simulation engineers or, if they are applied by non-expert simulation users, are not sufficiently accurate. Hence, a feature-based approach is presented, to support and automate the setup of design accompanying simulations.
Keywords: knowledge-based simulation; assistance system; feature; data mining

Feature based interpretation and reconstruction of structural topology optimization results - Stangl, Thomas; Wartzack, Sandro (Proceedings of the 20th International Conference on Engineering Design (ICED15), 2015)
The application of structural topology optimization is a common computer aided method to define the ideal design of a mechanical part. However, the problem remains, that the optimized component in its triangulated surface form cannot directly be used as model in the CAD based product development process. Due to different design aspects (even when using additive layer manufacturing technologies) the result needs to be interpreted and converted into a parametric feature based CAD model. After all, the current standard method is a time consuming, long-winded manual reconstruction. To put this right, this paper presents a semi-automatic approach to support the design engineer. The tool provides a way to interpret and reconstruct three dimensional topology optimization results as a parametric feature based CAD model. This approach automates the manual proceeding in order to generate a high quality solid CAD part. The functionality is demonstrated in a case study by an optimized and reconstructed motorcycle swing arm.
UnivIS-Import:2015-10-26:Pub.2015.tech.FT.FT-KLMEFK.featur
Keywords: Computational design synthesis; Computer aided design (CAD); Optimisation; Embodiment design

Feature-Based Reconstruction of Non-Beam-Like Topology Optimization Design Proposals in Boundary-Representation - Mayer, Johannes; Völkl, Harald; Wartzack, Sandro (Proceedings of the 33rd Symposium Design for X (DFX2022), 2022)
Geometry reconstruction from 3D topology optimization results to Computer Aided Design (CAD) is challenging, especially for automation and non-beam-like geometry. While the optimized model has polygonal format, product development with CAD requires analytical surfaces in Boundary Representation (B-Rep). In this paper, we present two approaches for an automated interpretation of surface-skeletons for CAD-reconstruction. This includes the question, when to convert the skeleton’s polygonal to analytical surfaces and how to conceptually incorporate CAD- features. One approach is based on decomposing the input in analytical, the other in polygonal surfaces. Both approaches work with specific skeleton-features and lead to a CAD-model with B-Rep-reconstruction. Exemplary results are presente
Keywords: Topology Optimization; Computer Aided Design; Geometry Post-Processing; Medial Axis Transform; Skeletonization

Feature-basierte Modellierung und Bauteilerkennung in automatisierten, konstruktionsbegleitenden Finite-Elemente-Analysen - Kestel, Philipp; Sprügel, Tobias; Wartzack, Sandro (34. CADFEM ANSYS Simulation Conference, 2016)
Computer-based simulation techniques such as Finite Element Analyses (FEA) gain huge attention in engineering design practice. However, an efficient simulation use requires an early application in the product development process. Furthermore, extensive specialist knowledge is a crucial prerequisite to perform reliable and efficient FEA. Due to time constraints, design accompanying FEA are performed only rarely by experienced simulation engineers or, if they are applied by non-expert simulation users, are not sufficiently accurate. In order to meet the increasing requirements on product development, the required expert knowledge has to be available for less experienced simulation users in design departments. Furthermore, recurring working steps like setting up FEA in Pre-Processing as well as evaluating the analysis results in Post-Processing have to be automated in order to accelerate these processes and ensure the computation accuracy. Thus, a knowledge-based FEA assistance system is developed to support less experienced simulation users setting up high-quality structural-mechanical FEA and to evaluate the results. The necessary knowledge is acquired and stored in a central knowledge base by expert interviews as well as by analyzing computation models and reports of previous applied and validated simulations in automated Text and Data Mining processes. In order to couple the design and FEA environments as well as to identify and specifically prepare the relevant model regions in automated simulation processes an extended feature library is developed and implemented. In addition, to recognize non-feature-based parts in the FEA results an approach based on spherical detector surfaces is used.

Femoral Shape and Size Variability from segmented CT datasets for patient-specific THA planning - Fleischmann, Christopher; Leher, Irina; Sesselmann, Stefan; Scherb, David; Wolf, Alexander; Miehling, Jörg; Wartzack, Sandro (Current Directions in Biomedical Engineering, 2020)
Biomechanical functionality of artificial hips strongly correlates with quality of life of patients after total hip arthroplasty. As the numbers of total hip arthroplasty are growing due to increasing life expectancy, biomechanical research is of utmost importance to improve the implants used and the operative procedures applied. Multibody simulation is used to predict forces and moments inside the human body. Generic scaling is usually performed to adapt the human models used in multibody simulation to individual patients. However, since the shape and size of the bones can vary considerably, this type of scaling often is not sufficient. In this work various CT datasets were used to quantify differences of individual femoral shapes, especially with regard to important biomechanical hip parameters, such as the CCD angle or the femoral offset. Our results prove that multibody simulations should be modeled more patientspecific to be able to calculate articular forces and moments more precisely, and thus, to improve surgical planning.

Fertigungsgerechtes Konstruieren - Potenzial und aktuelle Tendenzen - Wartzack, Sandro; Meerkamm, Harald (Werkstatt und Betrieb, 2000)
UnivIS-Import:2015-03-09:Pub.2000.tech.FT.FT-KLMEFK.fertig

Flexure pitch bearing concept for individual pitch control of wind turbines - Jüttner, Michael; Hasse, Alexander; Tremmel, Stephan (Wind Energy, 2017)
The excessive use of individual pitch control (IPC) for fatigue load reduction is accompanied by the uncertainty of potential bearing failures. This problem, which is due to the small swivel angles associated with IPC, arises because of the rolling and sliding contacts that occur with the rolling element bearings that are typically used. The use of a flexure bearing is proposed as a way of bypassing this issue. The flexure bearing enables a certain range of motion to be exclusively provided by elastic deformation. This article presents a novel bearing concept that is based on the hypothesis that such a flexure bearing can handle the unfavorable load conditions associated with IPC better than a rolling element bearing. Methods for the dimensioning of the aforementioned flexure bearing are therefore presented. The loads, particularly the required elastic rotation angle of the flexure bearing, are determined first. A promising design for the flexure bearing itself is then chosen and adapted to meet the specific requirements of IPC. These methods are applied to develop an initial conceptual design of the novel bearing unit for a 3-bladed wind turbine of about 3.6 MW. The result demonstrates the feasibility of the concept, and a final discussion presents further opportunities of the design that will make this concept satisfy the special requirements of IPC.
Keywords: blade bearing; concept; dimensioning; flexure; individual pitch control; wind turbine

Fluorescence Characteristics of the Fuel Tracer 1-Methylnaphthalene for the Investigation of Air-Fuel Ratio at Elevated Pressures and Temperatures - Retzer, Ulrich; Will, Thomas; Will, Stefan; Zigan, Lars (8th European Combustion Meeting, 2017)

FORCuDE@BEV: Neuer Forschungsverbund zum Customized Digital Engineering - Schleich, Benjamin; Wartzack, Sandro (WiGeP News, 2020)

Forschungsgruppe zum prozessorientierten Toleranzmanagement geht in die zweite Phase - Heling, Björn; Schleich, Benjamin; Wartzack, Sandro (WiGeP News, 2020)

Fostering self-efficacy through usability and emotional product design? An explorative study - Buker, Tina; Kamin, Stefan; van Remmen, Judith Sophie; Wartzack, Sandro; Miehling, Jörg (Research in Engineering Design, 2024)
Raising the user’s self-confidence is a promising strategy to reduce product-related user stigma. In the context of product usage, the commonly used term self-confidence refers to the psychological construct of self-efficacy. To strengthen a user’s self-efficacy through product design, providing both good usability and emotionality in a product seems to be a reasonable starting point. However, their suitability and validity for this purpose has not yet been sufficiently assessed. This paper examines whether self-efficacy would be associated with perceptions of a product’s usability and emotionality. By conducting an online survey (n = 105; stigma-sensitive product demonstrator: walker), it was confirmed that the perception of good usability and emotionality of walkers were positively associated with the user’s perceived self-efficacy. Moreover, a negative interaction effect was identified showing that the association between emotionality and self-efficacy increased with lower levels of perceived usability and vice versa. This may indicate that emotions can compensate the importance of usability at least to some exten
Keywords: User-centred design; Inclusive design; Product design; Product-related user stigma; Empirical study

Framework for the efficient Consideration of Non-Geometric Key Characteristics in Tolerance Analysis - Kopatsch, Jan; Wartzack, Sandro; Götz, Stefan (Tagungsband zum Stuttgarter Symposium für Produktentwicklung SSP 2025, 2025)
In the context of tolerance analyses, Key Characteristics (KCs) represent assembly properties that depend on the combined effect of part deviations. Non-geometric KCs, such as part stiffness, require the solution of partial differential equations (PDE), leading to increased computational effort compared to analytically solvable functional relations. To handle this issue, surrogate models replace the time-consuming PDE solutions. However, the inherent uncertainties affect the quality of the results of the determined KC values and therefore their significance. This uncertainty can be reduced by an extensive and precise training data set, but leads to increased computation times. To overcome this conflict and enable an efficient consideration of non-geometric KCs in tolerance analyses, a novel concept allowing the incorporation of several uncertainty levels in surrogate models by means of multi-level and -fidelity-based surrogate models is proposed. Thus, the time-consuming computation of exact PDE solutions and the uncertainty of the surrogate model is reduced, by including solutions with a lower level of detai
Keywords: Tolerance analysis; non-geometric key characteristics; surrogate model; multi-fidelity; multi-level

Frictional Behaviour and Surface Topography Evolution of DLC-Coated Biomedical Alloys - Nečas, David; Gelnar, Adam; Rothammer, Benedict; Marian, Max; Ranuša, Matúš; Wartzack, Sandro; Vrbka, Martin; Křupka, Ivan; Hartl, Martin (Biosurface and Biotribology, 2025)
Advanced engineering coatings offer a promising solution to enhance the longevity and performance of medical biomaterials in orthopaedic implants. This study hypothesises that diamond-like carbon (DLC) coatings exhibit distinct frictional performance based on substrate and counterface material. Three different DLC coatings were tested using a pin-on-plate test in four material combinations. Virgin and DLC-coated CoCrMo and Ti6Al4V pins were tested under sliding against UHMWPE and glass plates with simulated body fluid lubrication. Results revealed that coating composition significantly impacts frictional performance, with silicon- and oxygen-doped coatings showing great potential to minimise friction. Surprisingly, reducing contact pressure had either a neutral or somewhat negative effect. Future investigations will focus on long-term testing and lubrication analyses of these material combination
Keywords: Biotribolgy; CoCrMo; Diamond-like Carbon; Implant materials; Synovial joint; Ti6Al4V

Friction Losses of Cylindrical Roller Bearings Due to Axially Oscillating Shafts - Meinel, Andreas; Tremmel, Stephan (73rd STLE Annual Meeting and Exhibition, 2018)
Rolling element bearings experience dynamic axial thrust and shaft movements of various frequencies and amplitudes in a multitude of applications, such as drive trains, industrial gearboxes or heavy-duty machinery. These operating conditions often cause significant friction losses that entail higher operating temperatures and lower lubricant operating viscosities which may result in insufficient lubrication or even premature bearing failure. Therefore, in an experimental study, a cylindrical roller bearing has been subjected to dynamic axial shaft movements of various frequencies and amplitudes, utilizing a specifically designed test rig. Within the scope of this presentation, this test rig is briefly introduced and the experimental set-up is presented. The results obtained, which include measurements of axial friction forces between rollers and raceways, operating temperatures of inner and outer ring, test bearing friction moments, as well as cage slippage, are discussed in detai

Friction reduction in EHL contacts by surface microtexturing – tribological performance, manufacturing and tailored design - Tremmel, Stephan; Marian, Max; Zahner, Michael; Wartzack, Sandro; Merklein, Marion (Industrial Lubrication and Tribology, 2019)
Purpose – This paper aims to derive tailor-made microtextures for elastohydrodynamically lubricated (EHL) contacts under consideration of manufacturing possibilities. Design/methodology/approach – Component tests were used for the evaluation of the influence of surface texturing on the friction behavior in the cam/tappet contact. Furthermore, the manufacturing possibilities and limitations of a combined mEDM and micro coining process and the feasibility of integration into a forming process were studied. Finally, a methodology based on transient EHL simulations and a meta-model of optimal prognosis was exemplarily used for microtexture optimization. Findings – It was found that surface texturing in EHL contacts with high amount of sliding is promising. Moreover, the combination of mEDM and micro coining and the integration into established production processes allow the manufacturing of microtextures with desirable structural parameters and sufficient accuracy. Originality/value – This paper gives a holistic view on surface microtexturing over several phases of the product life cycle, from the design, over efficient manufacturing to application-related testin
Keywords: Friction; Elastohydrodynamic lubrication; Micro coining

Fringe projection profilometry in production metrology: A multi-scale comparison in sheet-bulk metal forming - Hinz, Lennart; Metzner, Sebastian; Müller, Philipp; Schulte, Robert Karl; Besserer, Hans-Bernward; Wackenrohr, Steffen; Sauer, Christopher; Kästner, Markus; Hausotte, Tino; Hübner, Sven; Nuernberger, Florian; Schleich, Benjamin; et al. (Sensors, 2021)
Fringe projection profilometry in combination with other optical measuring technologies has established itself over the last decades as an essential complement to conventional, tactile measuring devices. The non-contact, holistic reconstruction of complex geometries within fractions of a second in conjunction with the lightweight and transportable sensor design open up many fields of application in production metrology. Furthermore, triangulation-based measuring principles feature good scalability, which has led to 3D scanners for various scale ranges. Innovative and modern production processes, such as sheet-bulk metal forming, thus, utilize fringe projection profilometry in many respects to monitor the process, quantify possible wear and improve production technology. Therefore, it is essential to identify the appropriate 3D scanner for each application and to properly evaluate the acquired data. Through precise knowledge of the measurement volume and the relative uncertainty with respect to the specimen and scanner position, adapted measurement strategies and integrated production concepts can be realized. Although there are extensive industrial standards and guidelines for the quantification of sensor performance, evaluation and tolerancing is mainly global and can, therefore, neither provide assistance in the correct, application-specific positioning and alignment of the sensor nor reflect the local characteristics within the measuring volume. Therefore, this article compares fringe projection systems across various scale ranges by positioning and scanning a calibrated sphere in a high resolution grid.
CRIS-Team Scopus Importer:2021-04-09
Keywords: Coordinate metrology; Fringe projection; Production metrology; Sheet-bulk metal forming

FROM SKETCHES TO GRAPHS: A DEEP LEARNING BASED METHOD FOR DETECTION AND CONTEXTUALISATION OF PRINCIPLE SKETCHES IN THE EARLY PHASE OF PRODUCT DEVELOPMENT - Bickel, Sebastian; Götz, Stefan; Wartzack, Sandro (Proceedings of the Design Society, 2023)
The digitalization trend is finding its way more and more into product development, resulting in new frameworks to enhance product engineering. An integral element is the application of new techniques to existing data, which offers an enormous potential for time and cost savings, because duplicate work in product design and subsequent steps is avoided. The reduction of costs can be further increased through the application as early as possible in the product development process. One solution is outlined in this publication, where the source of available data is principle sketches from engineering design. These represent the basic solution for technical products in a simplified way and are often deployed in the early stages of the development process. This representation enables not only a search of similar sketches but also other fields of interest such as product optimization or the search of CAD-geometries. To utilize this data in a practical way, a procedure is presented which recognizes the symbols of the sketches and subsequently converts them into graphs. An exemplary dataset from different gearbox layouts is used to present the application opportunities by performing similarity searches with multiple input formats.<br
Keywords: Early design phases; Machine learning; Artificial intelligence; object detection; deep learning

From solid modelling to skin model shapes: Shifting paradigms in computer-aided tolerancing - Anwer, Nabil; Schleich, Benjamin; Mathieu, Luc; Wartzack, Sandro (CIRP Annals - Manufacturing Technology, 2014)
Product design requires the consideration of geometric models and representations that reflect shape deviations and support tolerance management issues. Computer-Aided Tolerancing (CAT) systems have been developed as simulation tools for modelling the effects of tolerances on digital product simulation. However, geometric variations cannot be addressed efficiently with regard to form deviations. This paper investigates the concepts of Skin Model Shapes, which provide a finite describability and the digital representation of the Skin Model concept, and their unified discrete geometry representation. New contributions to tolerance representation and analysis are presented. Applications and perspectives for CAT systems are highlighted as well.
Keywords: Product development; Tolerancing; Skin Model

From tolerance allocation to tolerance-cost optimization: a comprehensive literature review - Hallmann, Martin; Schleich, Benjamin; Wartzack, Sandro (International Journal of Advanced Manufacturing Technology, 2020)
It is widely acknowledged that the allocation of part tolerances is a highly responsible task due to the complex repercussions on both product quality and cost. As a consequence, since its beginnings in the 1960s, least-cost tolerance allocation using optimization techniques, i.e. tolerance-cost optimization, was continuously in focus of numerous research activities. Nowadays, increasing cost and quality pressure, availability of real manufacturing data driven by Industry 4.0 technologies, and rising computational power result in a continuously growing interest in tolerance-cost optimization in both research and industry. However, inconsistent terminology and the lack of a classification of the various relevant aspects is an obstacle for the application of tolerance-cost optimization approaches. There is no literature comprehensively and clearly summarizing the current state of the art and illustrating the relevant key aspects. Motivated to overcome this drawback, this article provides a comprehensive as well as detailed overview of the broad research field in tolerance-cost optimization for both beginners and experts. To facilitate the first steps for readers who are less familiar with the topic, the paper initially outlines the fundamentals of tolerance-cost optimization including its basic idea, elementary terminology and mathematical formulation. These fundamentals serve as a basis for a subsequent detailed discussion of the key elements with focus on the different characteristics concerning the optimization problem, tolerance-cost model, technical system model and the tolerance analysis model. These aspects are gathered and summarized in a structured mind map, which equips the reader with a comprehensive graphical overview of all the various facets and aspects of tolerance-cost optimization. Beside this, the paper gives a retrospect of the past fifty years of research in tolerance cost-optimization, considering 290 relevant publications. Based thereon, current issues and future research needs in tolerance-cost optimization were identified.<br

From vector-chain-based to geometrical Tolerance Analyses of Systems in Motion- the Use of Metamodels and their Evaluation - Walter, Michael; Wartzack, Sandro (Weimarer Stochastik- und Optimierungstage WOST 9.0, 2012)
UnivIS-Import:2015-04-16:Pub.2012.tech.FT.FT-KLMEFK.fromve

Frühzeitiges konstruktionsbegleitendes Toleranzmanagement - Götz, Stefan (FAU University Press, 2022)
Fertigungsbedingte Abweichungen sind unvermeidbar und definieren maßgeblich die Qualität eines Produkts. Das Robust Design sowie das Toleranzmanagement streben daher eine weitgehende Reduzierung der Auswirkungen von Abweichungen bzw. deren Kontrolle an. Wie umfassende Rückrufaktionen zeigen, stellt dies jedoch eine zunehmende Herausforderung dar. Experten empfehlen daher neben einer virtuellen Absicherung vor allem eine frühzeitige Berücksichtigung von Abweichungen im Produktentwicklungsprozess. Aufgrund mangelnden Wissens erfolgt dies jedoch meist erst in späten Entwicklungsphasen. Im Rahmen dieser Arbeit wurde daher eine Vorgehensweise entwickelt, die die Produktentwicklung zur frühzeitigen Abweichungsberücksichtigung befähigt. Dieses frühzeitige konstruktionsbegleitende Toleranzmanagement ist eng mit dem Produktentwicklungsprozess verknüpft und vereint Aspekte von Qualitätsmanagement, Robust Design und Toleranzmanagement. Es sieht unter anderem die automatische Ableitung von Zielgrößen des Toleranzmanagements aus Produktanforderungen, eine strukturierte Robustheitsbewertung sowie rechnergestützte Robustheitssynthese von Konzepten und eine automatisierte Toleranzvergabe sowie –analyse von ersten CAD-Entwürfen vor. Neben einer Sensibilisierung von Produktentwickelnden schafft dies die Grundlage für eine frühzeitige Einbindung sowie die Automatisierung der Abweichungsberücksichtigung und trägt so zu kürzeren Entwicklungszeiten sowie einer verbesserten Produktqualität be
Keywords: Toleranzmanagement; Produktentwicklung; Konstruktion; Qualitätsmanagement; Toleranz; Abweichung; Maschinenbau; Ingenieurwissenschaften; Produktionstechnik

Fully Automated Reconstruction of Topology Optimization Results with Feature Transformation and Curve Skeletonization! - Denk, Martin; Mayer, Johannes; Wartzack, Sandro (20. VDI-Kongress mit Fachausstellung SIMVEC, Aktuelle Herausforderungen bei der Auslegung und Absicherung von Fahrzeugsystemen, 2022)
The results of a topology optimization are oft en available as so-called dead geometry in the form of cell models or polygon meshes. This fo rmat can be derived directly from finite element meshes, but no feature-based CAD parametric is available. In this work, such results are automatically transformed into a be am parametric via so-called curve skeletons. However, the curves start within the geometry and often have to be manually extruded onto the surface. In this work, this skeletonization is modified so that the individual curves usefully begin at the surface. The improved approach is then tested on a variety of model
Keywords: Skeletonization; Topology Optimization; Reconstruction; Feature Transformation

Fully automated rotor inspection apparatus with high flexibility for permanent magnet synchronous motors using an improved hall sensor line array - Meyer, Alexander Wilhelm; Heyder, Andreas; Brela, Matthäus; Urban, Nikolaus; Sparrer, Johannes; Franke, Jörg (5th International Conference on Electric Drives Production, EDPC 2015, 2015)
As a result of the market expansion of permanent magnet synchronous motors due to the increasing demand for high-performance drives for a wide range of applications such as traction drives for electric mobility, positioning drives for machine tools as well as high-precision drives for special-purpose machines and the quality demands involved, in-line capable measurement technology is needed. Thus in the area of electric drives manufacturing the rejection rate is required to be reduced by early fault detection. This can be achieved by measuring the rotor excitation field created by permanent magnets prior to the assembly of rotor and stator. In this Paper an apparatus for fully automated inspection of both internal and external rotors within a wide range of dimensions is presented. This is done with the aid of a one dimensional Hall-Sensor line array, which is manufactured with high accuracy and the use of an open source CNC system. The presented device is capable for in-line operation at the end of the rotor assembly process chain to detect possible magnetization and assembly faults prior to the final assembly of the electric drive by visualization of the rotor excitation field.

Fully Automated Subdivision Surface Parametrization for Topology Optimized Structures and Frame Structures Using Euclidean Distance Transformation and Homotopic Thinning - Denk, Martin; Rother, Klemens; Paetzold, Kristin (Proceedings of the Munich Symposium on Lightweight Design 2020, 2021)
Polygon meshes and particularly triangulated meshes can be used to describe the shape of different types of geometry such as bicycles, bridges, or runways. In engineering, such polygon meshes can be supplied as finite element meshes, resulting from topology optimization or from laser scanning. Especially from topology optimization with low member size settings, frame-like polygon meshes with slender parts are typical and often have to be converted into a CAD (Computer-Aided Design) format, e.g., for further geometrical detailing or performing additional shape optimization. Especially for such frame-like geometries, CAD designs are constructed as beams with cross-sections and beam-lines, whereby the cross-section is extruded along the beam-lines or beam skeleton. In our research, automatic parameterization of polygon meshes into a subdivision surface representation is tried out. For this purpose, the beam-lines are approximated by computation of curved skeletons, which are determined by a homotopic thinning method. These skeleton lines are transformed into a subdivision surface control grid by using the Euclidean distance transformation.<br
Keywords: Topology Optimization; Reverse Engineering; Parametrization; Subdivision Surfaces

Functional Analysis of Components Manufactured by a Sheet-Bulk Metal Forming Process - Hetzel, Andreas; Schulte, Robert Karl; Vogel, Manfred; Lechner, Michael; Besserer, Hans-Bernward; Maier, Hans Juergen; Sauer, Christopher; Schleich, Benjamin; Wartzack, Sandro; Merklein, Marion (Journal of Manufacturing and Materials Processing, 2021)
Due to rising demands regarding the functionality and load-bearing capacity of functional components such as synchronizer rings in gear systems, conventional forming operations are reaching their limits with respect to formability and efficiency. One way to meet these challenges is the application of the innovative process class of sheet-bulk metal forming (SBMF). By applying bulk forming operations to sheet metal, the advantages of both process classes can be combined, thus realizing an optimized part weight and an adapted load-bearing capacity. Different approaches to manufacturing relevant part geometries were presented and evaluated regarding the process properties and applicability. In this contribution, a self-learning engineering workbench was used to provide geometry-based data regarding a novel component geometry with circumferential involute gearing manufactured in an SBMF process combination of deep drawing and upsetting. Within the comprehensive investigations, the mechanical and geometrical properties of the part were analyzed. Moreover, the manufactured components were compared regarding the increased fatigue strength in cyclic load tests. With the gained experimental and numerical data, the workbench was used for the first time to generate the desired component as a CAD model, as well as to derive design guidelines referring to the investigated properties and fatigue behavior.<br
Keywords: sheet-bulk metal forming; mechanical properties; self-learning engineering workbench; functional behavior; fatigue life modeling; Z-integral approach

Funktionsorientiertes Interaktionsmodell zur Simulation menschlicher Bewegungen während der Nutzer-Produkt Interaktion - Krüger, Daniel; Wartzack, Sandro (Design for X - Beiträge zum 25. DfX-Symposium, 2014)
UnivIS-Import:2015-10-26:Pub.2014.tech.FT.FT-KLMEFK.funkti

Fuzzy Sensitivity Analysis in the Context of Dimensional Management - Oberleiter, Thomas; Heling, Björn; Schleich, Benjamin; Willner, Kai; Wartzack, Sandro (ASCE-ASME Journal of Risk and Uncertainty in Engineering Systems, Part B: Mechanical Engineering, 2018)
Real components always deviate from their ideal dimensions. This makes every component, even a serial production, unique. Although they look the same, differences can always be observed due to different scattering factors and variations in the manufacturing process. All these factors inevitably lead to parts that deviate from their ideal shape and, therefore, have different properties than the ideal component. Changing properties can lead to major problems or even failure during operation. It is necessary to specify the permitted deviations to ensure that every single product nevertheless meets its technical requirements. Furthermore, it is necessary to estimate the consequences of the permitted deviations, which is done via tolerance analysis. During this process, components are assembled virtually and varied with the uncertainties specified by the tolerances. A variation simulation is one opportunity to calculate these effects for geometric deviations. Since tolerance analysis enables engineers to identify weak points in an early design stage, it is important to know the contribution that every single tolerance has on a certain quality-relevant characteristic, to restrict or increase the correct tolerances. In this paper, a fuzzy-based method to calculate the sensitivity is introduced and compared with the commonly used extended Fourier amplitude sensitivity test (EFAST) method. Special focus of this work is the differentiation of the sensitivity for the total system and the sensitivities for the subsystems defined by the α-cuts of the fuzzy numbers. It discusses the impact of the number of evaluations and nonlinearity on sensitivity for EFAST and the fuzzy-based meth

Gap hull estimation for rigid mechanical joints considering form deviations and multiple pairs of mating surfaces - Schleich, Benjamin; Wartzack, Sandro (Mechanism and Machine Theory, 2018)
The embodiment of mechanical joints is a demanding activity during the design of mechanism. In this context, particularly the assessment of the effects of geometrical deviations on the behaviour of the mechanical joint is of strong importance. This paper presents an approach to the gap hull estimation for mechanical joints considering form deviations. The novelty of this approach lies in the ability to analyse the behaviour of mechanical joints considering multiple pairs of mating surfaces. The application of this method to a prismatic as well as to a cylindrical joint prove the versatility of the method regarding different kinds of joints with multiple pairs of contact surfaces. Moreover, the results of the application of this approach to the tolerance analysis of a two-pin-two-hole assembly confirm the importance of considering form deviations in the tolerance analysis and in the design of mechanical joints and mechanism. <br
Keywords: Gap hull; Clearance space; Skin model shapes; Tolerance analysis

Gaussian Process based approach for automatic knowledge acquisition - Breitsprecher, Thilo; Kestel, Philipp; Dingfelder, Christian; Wartzack, Sandro (Proceedings of the 13th International Design Conference, 2014)
New manufacturing processes like sheet-bulk metal forming offer a high degree of freedom to the design engineer, because complex features elements (teeth, grooves, etc.) can be manufactured, that were not realizable before or only at high costs. In order to make use of this new design freedom the design engineer can be assisted by knowledge based systems, whereas the knowledge acquisition is the most crucial step in the development of a KBE-system. This paper presents a Gaussian process based approach for automatic acquisition of design-relevant and manufacturing related knowledge.

Generating Digital Twins for Path-Planning of Autonomous Robots and Drones Using Constrained Homotopic Shrinking for 2D and 3D Environment Modeling - Denk, Martin; Bickel, Sebastian; Steck, Patrick; Götz, Stefan; Völkl, Harald; Wartzack, Sandro (Applied Sciences, 2022)
A digital twin describes the virtual representation of a real process. This twin is constantly updated with real data and can thus control and adapt the real model. Designing suitable digital twins for path planning of autonomous robots or drones is often challenging due to the large number of different dynamic environments and multi-task and agent systems. However, common path algorithms are often limited to two tasks and to finding shortest paths. In real applications, not only a short path but also the width of the passage with a path as centered as possible are crucial, since robotic systems are not ideal and require recalibration frequently. In this work, so-called homotopic shrinking is used to generate the digital twin, which can be used to extract all possible path proposals including their passage widths for 2D and 3D environments and multiple tasks and robots. The erosion of the environment is controlled by constraints such that the task stations, the robot or drone positions, and the topology of the environment are considered. Such a deterministic path algorithm can flexibly respond to changing environmental conditions and consider multiple tasks simultaneously for path generation. A distinctive feature of these paths is the central orientation to the non-passable areas, which can have significant benefits for worker and patient safety. The method is tested on 2D and 3D maps with different tasks, obstacles, and multiple robots. For example, the robust generation of the digital twin for a maze and also the dynamic adaptation in case of sudden changes in the environment is covered. This variety of use cases and the comparison with alternative methods result in significant advantages, such as high robustness, consideration of multiple targets, and high safety distances to obstacles and areas that cannot be traversed. Finally, it was shown that the environment for the digital twin can be reduced to reasonable paths by constrained shrinking, both for real 2D maps and for complex virtual 2D and 3D maps.

Generating hybrid geometry models for more precise simulations by combining parametric CAD-models with 3d surface detected geometry inserts - Katona, Sebastian; Koch, Michael; Wartzack, Sandro (Proceedings of the 20th International Conference on Engineering Design (ICED2015), 2015)
In general, every component shows differences to its ideal geometry of the designed CAD-model, i.e. due to deformations in the production process. Despite knowing the effects of deformations, the product developer always uses the ideal, non-deformed design model of the CAD-system for FE-simulations of a component. It seems rather doubtful that further refinement of simulation methods (e.g. using different non-linearities) makes sense, if the real manufactured geometry of the component is not considered for in the simulation process. Therefore, this paper describes an approach to use hybrid geometry models for simulations, which are mostly built of the parametric CAD-model, but areas with large deviations are substituted with surface reconstructed scan-inserts based on 3d surface scanned data, reconstructed to NURBS-patches. This procedure allows a more precise simulation as it considers deviations by minimizing the amount of data and the time for model preparation.
Keywords: CAD; Product modelling; models; Simulation; Reverse Engineering

Generating Manufacturing Distributions for Sampling-based Tolerance Analysis using Deep Learning Models - Schächtl, Paul; Roth, Martin; Bräu, Julian; Götz, Stefan; Schleich, Benjamin; Wartzack, Sandro (Procedia CIRP, 2024)
Sampling-based tolerance analysis is a powerful tool for evaluating the quality of functional products, but requires realistic manufacturing distributions. However, the determination of resulting manufacturing distributions is usually associated with a high financial and time expenditure, especially for novel technologies such as Additive Manufacturing. Usually, sampling techniques are used to reproduce the original distribution of manufacturing variations based on statistical moments. In most cases, simplifying assumptions are made for this purpose, potentially leading to an inadequate representation of the correlation between machine and process parameters in the resulting distribution. In the worst case, this can lead to a falsification of the tolerance analysis results. Aiming to address this challenge, this paper presents an approach to imitate real-world manufacturing distributions using generative Machine Learning techniques based on Deep Learning with small real data sets. This enables a realistic reproduction of quasi-real manufacturing distributions and omits conventional sampling techniques. The general procedure and its applicability are shown via illustrative use cases from the tolerancing domai
Keywords: Tolerance Analysis; Sampling; Deep Learning models; Deep Generative Models; Manufacturing distributions; Data Augmentation; Synthetic Data

Generation of deviated geometry based on manufacturing process simulations - Schleich, Benjamin; Wartzack, Sandro (Proceedings of the 9th Optimization and Stochastic Days 2012, 2012)
Every process underlies fluctuations of input and ambient parameters. In manufacturing processes, these fluctuations manifest i.a. in geometric deviations of manufactured workpieces which in turn hugely decrease the function and quality of technical products. Therefore, these deviations have to be limited by geometric tolerances. In this regard, tolerance simulations aim at determining and quantifying the effects of deviations on the product quality. However, in order to obtain resilient predictions about the impacts of process fluctuations on the quality of technical products realistic samples of deviated geometries have to be available which reflect the observable geometric manufacturing deviations. The proposed approach employs methods from computer vision and regression analysis for generating realistic geometry samples based on a limited set of observations, e.g. gathered from manufacturing process simulations or measurements, considering manufacturing process parameters. An exemplary application using the software "Statistics on Structure" (SoS) and "optiSLang" by dynardo GmbH is given.

Generative adversarial networks for tolerance analysis - Schleich, Benjamin; Qie, Yifan; Wartzack, Sandro; Anwer, Nabil (CIRP Annals - Manufacturing Technology, 2022)
Many activities in design and manufacturing rely on realistic product representations considering geometrical deviations to assess their effects on the product function and quality. Though several approaches for tolerance analysis have been developed, they imply several shortcomings, such as the lack of form deviations consideration and the high manual modelling effort. In this paper, a novel shape-agnostic approach supported by generative adversarial networks is developed for the automated generation of part representatives with geometrical deviations. A workflow for generating these variational part representatives is highlighted and tolerance analysis case studies demonstrate the effectiveness of the proposed approach.<br
Keywords: Design; Tolerancing; Machine learning

GENERIC APPROACH TO PLAUSIBILITY CHECKS FOR STRUCTURAL MECHANICS WITH DEEP LEARNING - Sprügel, Tobias; Schröppel, Tina; Wartzack, Sandro (Proceedings of the 21st International Conference on Engineering Design (ICED17), 2017)
The simulation of product behavior is a vital part in virtual product development, but currently there is no tool or method available that can examine the quality of FE simulations and decide automatically on whether a simulation is plausible or non-plausible. In the paper a method is presented that enables automatic plausibility checks on basis of empirical simulation datasets. Nodal simulation data is transformed to numerical arrays, of fixed size, using virtual spherical detector surfaces. Afterwards the arrays are used to train a Deep Convolutional Neural Network (AlexNet). The Neural Network can then be used for plausibility checks of FE simulations (structural mechanics). In a first application a Deep Convolutional Neural Network is trained with simulation data of a demonstrator part, the rail of speed inline skates. After the GPU training of the Neural Network, further simulations are evaluated with the net. These simulations were not part of the training data and are used to calculate the prediction quality of the Neural Network. This approach is to support development engineers during design accompanying FEA in virtual product development.

Geometrical Optimization of the EHL Roller Face/Rib Contact for Energy Efficiency in Tapered Roller - Wirsching, Sven; Marian, Max; Bartz, Marcel; Stahl, Thomas; Wartzack, Sandro (Lubricants, 2021)
In the context of targeted improvements in energy efficiency, secondary rolling bearing contacts are gaining relevance. As such, the elastohydrodynamically lubricated (EHL) roller face/rib contact of tapered roller bearings significantly affects power losses. Consequently, this contribution aimed at numerical optimization of the pairing’s macro-geometric parameters. The latter were sampled by a statistical design of experiments (DoE) and the tribological behavior was predicted by means of EHL contact simulations. For each of the geometric pairings considered, a database was generated. Key target variables such as pressure, lubricant gap and friction were approximated by a meta-model of optimal prognosis (MOP) and optimization was carried out using an evolutionary algorithm (EA). It was shown that the tribological behavior was mainly determined by the basic geometric pairing and the radii while eccentricity was of subordinate role. Furthermore, there was a trade-off between high load carrying capacity and low frictional losses. Thereby, spherical or toroidal geometries on the roller end face featuring a large radius paired with a tapered rib geometry were found to be advantageous in terms of low friction. For larger lubricant film heights and load carrying capacity, spherical or toroidal roller on toroidal rib geometries with medium radii were favorable.
Keywords: tapered roller bearing; energy efficiency; elastohydrodynamic lubrication; macro-geometry; machine learning; meta-modeling; multi-objective optimization; genetic algorithm

Geometrical Variations Management 4.0: towards next Generation Geometry Assurance - Schleich, Benjamin; Wärmefjord, Kristina; Söderberg, Rikard; Wartzack, Sandro (Procedia CIRP, Volume 75, 2018)
Product realization processes are undergoing radical change considering the increasing digitalization of manufacturing fostered by cyber-physical production systems, the internet of things, big data, cloud computing, and the advancing use of digital twins. These trends are subsumed under the term “industry 4.0” describing the vision of a digitally connected manufacturing environment. The contribution gives an overview of future challenges and potentials for next generation geometry assurance and geometrical variations management in the context of industry 4.0. Particularly, the focus is set on potentials and risks of increasingly available manufacturing data and the use of digital twins in geometrical variations management.
Keywords: Industry 4.0; Digital Twin; Geometry Assurance

Gesputterte MoS2-Gleitschichten für wechselnde Umgebungsbedingungen - Vierneusel, Bernd; Tremmel, Stephan; Wartzack, Sandro; Schneider, Thomas; Gradt, Thomas (Tagungsband zur 10. VDI-Fachtagung Gleit- und Wälzlagerungen 2015: Gestaltung, Berechnung, Einsatz (VDI-Berichte 2202), 2013)
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.gesput

Gezielte Anpassung lokaler Reibungszustände unter Einsatz wolframmodifizierter amorpher Kohlenstoffschichten (a-C:H:W) - Weikert, Tim; Tremmel, Stephan; Wartzack, Sandro (56. Tribologie-Fachtagung. Reibung, Schmierung und Verschleiß. Band I, 2015)
Im Rahmen der Herstellung funktionsintegrierter Blechbauteile mithilfe von Umformoperationen der Blechmassivumformung stellen lokal angepasste Reibungszustände eine Möglichkeit zur besseren Ausformung kompliziert geformter Bauteilgeometrien dar. Vor diesem Hintergrund finden unterschiedliche tribologische Beschichtungen in der Umformtechnik nicht nur zum Schutz hoch beanspruchter Werkzeugoberflächen, sondern vielmehr auch zur Anpassung der Reibungszustände Verwendung. Als globale Oberflächenmodifikation auf das Werkzeug aufgebracht, ist eine lokale Anpassung der Reibungszustände mithilfe von Beschichtungen jedoch nur eingeschränkt möglich. Im Rahmen dieses Beitrags wurde daher der Einsatz verschiedener Maskierungsverfahren bei der Herstellung von in der Umformtechnik häufig eingesetzten Beschichtungen untersucht. Mithilfe starrer und flexibler Masken wurden in definierten Oberflächenbereichen beschichteter Probekörper unterschiedliche funktionale Schichtlagen eines Mehrlagenschichtsystems offengelegt. Als funktionale Schichtlagen wurden Schichtlagen aus CrN und einer Variante einer wolframmodifizierten amorphen Kohlenstoffschicht (a-C:H:W) (Typ A), sowie verschiedene a-C:H:W-Schichtvarianten mit unterschiedlichen Reibungszahlen (Typ B) gewählt. Die durch die Maskierung entstehenden Schichtkantenbereiche zeigten Einflüsse der Maskierungsverfahren sowie der eingesetzten Masken. Darüber hinaus konnten in Stift-Scheibe-Versuchen unterschiedliche Reibungsniveaus in den Verläufen der Reibungszahlen lediglich bei Proben des Schichtsystems Typ A infolge verschiedener Tribomechanismen der funktionalen Schichtlagen identifiziert werden.
Keywords: Lokal angepasste Reibungszustände; diamantähnlicher amorpher Kohlenstoff; Stift-Scheibe-Versuch; Maskierungsverfahren

Gezielte Anpassung lokaler Reibungszustände unter Einsatz wolframmodifizierter amorpher Kohlenstoffschichten - Weikert, Tim; Tremmel, Stephan; Wartzack, Sandro (Tribologie und Schmierungstechnik, 2016)
Bei der Herstellung funktionsintegrierter Blechbauteile mithilfe von Umformoperationen der Blechmassivumformung stellen lokal angepasste Reibungszustände eine Möglichkeit zur besseren Ausformung kompliziert geformter Bauteilgeometrien dar. Im Rahmen dieser Untersuchungen wird daher der Einsatz verschiedener Maskierungsverfahren bei der Herstellung typischer Werkzeugbeschichtungen betrachtet, um auf diese Weise tribologisch wirksame Oberflächenbereiche lokal voneinander abzugrenzen. Mithilfe starrer und flexibler Masken werden in definierten Oberflächenbereichen beschichteter Probekörper unterschiedliche funktionale Schichtlagen eines Mehrlagenschichtsystems offengelegt. Hierbei kommen funktionale Schichtlagen aus Chromnitrid (CrN) und verschiedenen Varianten wolframmodifizierter amorpher Kohlenstoffschichten (a‑C:H:W) mit unterschiedlichen Reibungszahlen zum Einsatz. Dabei zeigen die durch die Maskierung entstehenden Schichtkantenbereiche Einflüsse der Maskierungsverfahren sowie der eingesetzten Masken. Für maskiert beschichtete Probekörper können in Stift-Scheibe-Versuchen unterschiedliche Reibungszustände identifiziert werden.
Keywords: Lokal angepasste Reibungszustände; amorphe Kohlenstoffschichten; a-C:H:W; Blechmassivumformung; Stift-Scheibe-Versuch; Maskierungsverfahren

Graphenbasierte Toleranzbetrachtung in der frühen Entwurfsphase des Produktentwicklungsprozesses - Götz, Stefan; Schleich, Benjamin; Wartzack, Sandro (Summer School Toleranzmanagement - Beiträge zur 3. Summer School - September 2017, 2017)

GreenBearings 2 - Vermeidung konventioneller Schmierstoffe in Wälzlagerungen durch tribologische Schichten und Erhöhung der Gebrauchsdauer trockenlaufender Wälzlager - Kröner, Julia; Tremmel, Stephan; Kursawe, Serge; Musayev, Yashar; Wartzack, Sandro (2016)

GreenBearings – Friction Behaviour of DLC-Coated Dry Running Deep Groove Ball Bearings - Kröner, Julia; Tremmel, Stephan; Kursawe, Serge; Musayev, Yashar; Hosenfeldt, Tim; Wartzack, Sandro (Applied Mechanics and Materials, 2015)
Due to the use of rolling bearings instead of plain bearings friction and wear are drastically reduced in all kind of machines. However, despite the high technical standard of modern rolling bearings there is still a significant potential for optimization. Preliminary Studies show a reduction of the friction torque of up to 44 % compared to conventional rolling bearings because of the use of tribological coatings in certain applications. Based on the millionfold usage of rolling bearings in all industrial fields the reduced lost energy adds up to a remarkable potential for energy savings. If friction and wear are lowered sufficiently, the use of conventional lubricants based on mineral oil can be successively decreased or even completely avoided. In the latter case, the so-called dry running of the rolling bearing, the energy consumption of machines and systems can additionally be reduced significantly. For example, pumping stations or compressed air units, which would be necessary for transporting or spraying the lubricants, can then be saved. This paper presents first results of DLC-coated deep groove ball bearings, which are tested in a four-bearing-test-rig under purely radial load with respect to their friction and wear behaviou
Keywords: Dry Running; DLC Coating; Friction Reduction; Deep Groove Ball Bearings; Four-Bearing-Test-Rig; Energy Efficiency

GreenBearings: Minimierung und Vermeidung konventioneller Schmierstoffe in Wälzlagerungen durch tribologische Schichten - Kröner, Julia; Tremmel, Stephan; Kursawe, Serge; Musayev, Yashar; Hosenfeldt, Tim; Wartzack, Sandro (2015)

GreenBearings: Minimization and Avoidance of Conventional Lubricants in Rolling Bearings by Tribological Coatings - Kröner, Julia; Tremmel, Stephan; Kursawe, Serge; Musayev, Yashar; Hosenfeldt, Tim; Wartzack, Sandro (2014)

Halide-Free Synthesis and Tribological Performance of Oil-Miscible Ammonium and Phosphonium-Based Ionic Liquids - Westerholt, Antje; Weschta, Martin; Bösmann, Andreas; Tremmel, Stephan; Korth, Yasmin; Wolf, Marcus J.; Schlücker, Eberhard; Wehrum, Natalie; Lennert, Angela; Uerdingen, Marc; Holweger, Walter; Wartzack, Sandro; et al. (ACS Sustainable Chemistry & Engineering, 2015)
Due to their low vapor pressures, nonflammability, high thermal stabilities, and excellent tribological properties ionic liquids (ILs) are highly attractive lubricant base oils and additives. However, for practical applications of ILs in lubrication, two requirements are often limiting, the required miscibility with standard mineral oils (≥5 wt %) and the complete absence of corrosive halide ions in the ionic liquid. Moreover, the need for full compatibility with standard oil additives reduces the number of potential IL-based lubricant additives even further. In this contribution, an economic halide-free synthesis route to oil-miscible ionic liquids is presented, and very promising tribological properties of such ILs as base oil or additive are demonstrated. Therefore, sliding tests on bearing steel and XPS analysis of the formed surface films are shown. Corrosion test results of different bearing metals in contact with our halide-free ILs and (salt) water prove their applicability as real life lubricants. In the sustainable chemistry and engineering context, we present a halide-free design approach for ionic performance chemicals that may contribute to significant energy savings due to their enhanced lubrication properties.
Keywords: Halide-free; Ionic liquid; Lubrication; Noncorrosive; Oil-miscible; XPS

Handling Sampling-induced Uncertainties in Tolerance-Cost Optimization - Roth, Martin; Schleich, Benjamin; Wartzack, Sandro (Procedia CIRP, 2022)
Tolerance allocation is an essential part of detail design and an important interface between design and production. Its goal is to select tolerance values as tight as necessary, to reliably assure total product quality considering variation, but at the same time as wide as possible, to allow for a cost-optimal fabrication of the individual parts. A consequent front-loading of manufacturing information is thus inevitable for a realistic consideration of the given manufacturing conditions enabling an early, optimal process planning. In this context, sampling-based tolerance-cost optimization has proven its suitability as an optimization-based tolerance allocation technique because it allows a realistic consideration of part tolerance distributions as well as the selection of cost-minimal combinations of manufacturing machines and processes for each part. However, the potential of machine selection in tolerance-cost optimization is currently limited since it does not support distributed manufacturing on several machines with individual batch sizes. Motivated to close this gap, this article presents a novel optimization-based method for concurrent tolerance and machine allocation. The consideration of mixed batches from individually allocated machines requires the extension of the mathematical definition of the tolerance-cost optimization problem and its solution by advanced optimization and sampling strategies. Its exemplary application to a use case shows its potentials and proves that balancing tolerance values, machines and batch sizes can help to further increase the potential of tolerance-cost optimization. Hence, the presented approach supports a further shift to a manufacturing-oriented interpretation of tolerance allocation in design.<br
Keywords: Tolerance-cost optimization; Tolerance allocation; Sampling-based tolerance analysis; Uncertainty; Metaheuristic optimization

Handlungsempfehlungen für die Entwicklung Digitaler Zwillinge in der Antriebstechnik - Wilking, Fabian; Fett, Michel; Götz, Stefan; Kirchner, Eckhard; Wartzack, Sandro (WiGeP News, 2023)

Handlungsempfehlungen für die Produktentwicklung nicht-idealer bewegter technischer Systeme - Walter, Michael; Wartzack, Sandro (Design for X. Beiträge zum 22. DfX-Symposium, 2011)
UnivIS-Import:2015-04-16:Pub.2011.tech.FT.FT-KLMEFK.handlu

Herausforderungen bei der Verknüpfung von Gestaltungs- und Toleranzdomäne zur Robustheitsbewertung von Produktkonzepten - Grauberger, Patric; Bremer, Frank; Matthiesen, Sven; Götz, Stefan; Schleich, Benjamin; Wartzack, Sandro (Summer School Toleranzmanagement - Beiträge zur 4. Summer School - September 2020, 2020)

High-precision force control using selective compliant mechanisms - von Zitzewitz, Joachim; Vallery, Heike; Hasse, Alexander; Courtine, Grégoire (EPFL-TALK-196614, 2013)
Keywords: selective compliant mechanisms; High-precision force control

High temperature diffusion chromizing as a successful method for CVD-diamond coating of steel Part II - Schwarz, Sergej; Rosiwal, Stefan; Musayev, Yashar; Singer, Robert (Diamond and Related Materials, 2003)
UnivIS-Import:2015-03-09:Pub.2003.tech.IW.LWWTM.highte

High temperature diffusion chromizing as a sucsessful method for CVD-diamond coating of steel - Schwarz, Sergej; Musayev, Yashar; Rosiwal, Stefan; Schaufler, Christian; Singer, Robert; Meerkamm, Harald (Diamond and Related Materials, 2002)
UnivIS-Import:2015-03-09:Pub.2002.tech.IW.LWWTM.highte

Holistisches Toleranzmanagement am Lehrstuhl für Konstruktionstechnik - Wartzack, Sandro; Götz, Stefan; Bode, Christoph; Franz, Michael; Freitag, Stephan; Horber, Dennis; Kramer, Vincent; Roth, Martin; Schächtl, Paul (Tagungsband der 5. Summer School Toleranzmanagement 2023, 2023)

How can Computer Aided Tolerancing support Closed Loop Tolerance Engineering? - Schleich, Benjamin; Wartzack, Sandro (Procedia CIRP, 2014)
Since geometric deviations decrease the quality and functional compliance of mechanical products, geometric variations management is an important issue for quality-aware companies in all phases of the product life-cycle. In this regard, the Closed Loop Tolerance Engineering Model highlights the main activities during geometric variations management and can be used to analyse the relations between the different involved actors. Though computer aided engineering tools are widely spread in product development practice with the aim to ease product design and analysis, these tools are mainly used separately and are not integrated in a coherent virtual geometric variations management process. Therefore, in this paper, the prerequisites for a holistic computer aided tolerancing process during product development based on the CLTE model are analysed. The main question answered is, which tolerance simulation tools are required and how should they be connected in order to enable a coherent and integrated computer-aided tolerancing process. Based thereon, important software tools are identified and drawbacks as well as main potentials for improvement are carved out. The novelty of the contribution can be found in the consideration of the geometric variations management process from a computer-aided tolerancing point of view and in addressing possible improvements for the development of software tools for a coherent and complete computer aided geometric variations management process.
UnivIS-Import:2015-04-16:Pub.2014.tech.FT.FT-KLMEFK.howcan
Keywords: Design for X; Robust Design; Product Quality

How Do Digital Engineering and Included AI Based Assistance Tools Change the Product Development Process and the Involved Engineers - Bickel, Sebastian; Sprügel, Tobias; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the 22nd International Conference on Engineering Design (ICED19), 2019)
Current trends in product development are digital engineering, the increasing use of assistance tools based on artificial intelligence and in general shorter product lifecycles. These trends and new tools strongly rely on available data and will irreversibly change established product development processes. One example for such a new data driven tool is the plausibility check of linear finite element simulations with Convolutional Neural Networks (CNN). This tool is capable of determining whether new simulation results are plausible or non-plausible according to numeric input data. The digitalization and the increased use of data driven tools employing algorithms known from Artificial Intelligence also shifts the roles of many involved engineers. This paper describes and highlights this transition from current product development processes to a data driven / simulation driven product development process. Particularly, the shifts and changes of different roles and domains are illustrated and an example for changing roles in the design and simulation department is described. Furthermore, required adjustments in the design process are derived and compared to the current status.<br
Keywords: Digital Engineering; Machine learning; Data Driven Design; Organisation of product development; Artificial intelligence

How does testing affect the availability of aging software systems? - Grottke, Michael; Schleich, Benjamin (Performance Evaluation, 2013)
This paper proposes an approach to examining how testing affects the operational behavior of aging software systems. Such an approach requires models for the testing phase and the operational phase that explicitly account for crash failures due to both aging-related and non-aging-related bugs. We develop appropriate semi-Markov models and derive expressions for computing the respective transient and steady-state probabilities needed. Our numerical examples suggest that disregarding the effects of non-aging-related bugs can result in wrong conclusions about the testing phase and the operational phase. Moreover,weshow how to combine the two models for a joint analysis in which metrics of interest concerning the operational phase, such as the optimal rejuvenation rate, are random variables whose distributions are influenced by the potential outcomes of testing. © 2012 Elsevier B.V. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2013.tech.FT.FT-KLMEFK.howdoe
Keywords: Rejuvenation rate; Semi-Markov process; Software aging; Steady-state availability; Testing phase; Transient state probability

How the distribution of the number of items rated per user influences the quality of recommendation - Grottke, Michael; Schleich, Benjamin (Performance Evaluation, 2013)

How to consider Over-constrained Assemblies with Gaps in Tolerance-Cost Optimization? - Hallmann, Martin; Schleich, Benjamin; Wartzack, Sandro (Procedia CIRP, 2020)
Exact Constraint Design is well established in design theory to ensure a robust and predictable system behavior. In practice, however, it is often inevitable to deviate from this basic concept so that parts are constrained several times for rigidity or resilience. In doing so, gaps between mating parts have to be added to ensure assemblability and functionality. Despite the essential impact of gaps on the total product functionality, occurring uncertainties in part positioning are mostly neglected in tolerance analysis. In the context of tolerance-cost optimization, they have not been studied in detail so far. To overcome this drawback, this article addresses the research question how over-constrained systems with gaps can be considered in tolerance-cost optimization ensuring the identification of both reliable and cost-optimal tolerance values. Based on an initial discussion on the complexity of tolerance analysis of over-constrained systems with gaps, their impact on the results and the efficiency of tolerance-cost optimization are discussed. With the aim to ensure a sufficient model accuracy in time-consuming applications, a framework for tolerance-cost optimization considering assemblies with multiple gap configurations based on surrogate models is presented and applied to a case study of industrial complexity. In doing so, a novel framework for a proper and efficient modelling of systems with gaps in tolerance-cost optimization supporting both researchers and practitioners is presente
Keywords: Tolerance-cost optimization; Least-cost tolerance allocation; Over-constrained assembly; Tolerance analysis

How to determine the influence of geometric deviations on elastic deformations and the structural performance? - Schleich, Benjamin; Wartzack, Sandro (Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 2013)
Geometric deviations are observable on every manufactured part since manufacturing processes are inherently imprecise and measuring processes always involve uncertainties. These geometric deviations have influences on the function and the quality of the product. Therefore, allowable limits for these geometric deviations, depicted as geometric tolerances, have to be set. They define the allowable geometric deviations of a part for which the product function is guaranteed. In this context, elastic deformations and the structural performance are key aspects. However, the manufacturing-caused geometric deviations have an influence on the elastic deformations during use and the structural performance of the parts. In other words, there are interdependencies between geometric deviations and elastic deformations which affect the dimensional accuracy of a loaded part in an assembly. Therefore, this article proposes an approach for determining the impact of geometric deviations on the structural performance. This approach employs techniques such as sensitivity analysis, analysis of robustness and evaluation of reliability, and aims at providing information about the expectable elastic deformations and structural performance to geometric tolerancing. It can be concluded that geometric deviations can have a big impact on the structural performance, and thus, not only parametric deviations but also geometric deviations regarding the form and shape of a part itself should be taken into account within the structural performance analysis and tolerance simulations.
Keywords: Structural Performance; Computer-Aided Tolerancing; Geometric deviations

How to identify relevant product properties in the context of user-product interaction? - Schröppel, Tina; Miehling, Jörg; Wartzack, Sandro (Procedia CIRP, 2020)
A smooth and pleasurable user-product interaction (UPI) forms the basis of a successful user-centred design. An essential part of achieving this is the consideration of the ‘right’ product properties whose identification currently requires huge monetary, temporal and personnel effort. This contribution presents a more sufficient approach for identifying relevant product properties in the context of UPI as well as its first evaluation. To identify relevant properties, the UPI is first described by standard interactions which are secondly used as input for searching a knowledge base. For the initial evaluation an application example (percussing drill) is conducted. It shows that the outcome of the approach is indeed plausible but usability should be improved. Future research focuses on a deeper evaluation and improvements regarding accessibility and traceability.<br
Keywords: user-centred design; user-product interaction; product properties; relevance; evaluation; user-satisfaction; user experience; usability

Humidity resistant MoS2 coatings deposited by unbalanced magnetron sputtering - Vierneusel, Bernd; Schneider, Thomas; Tremmel, Stephan; Wartzack, Sandro; Gradt, Thomas (Surface & Coatings Technology, 2013)
MoS2 is a suitable solid lubricant for environments free of oxygen or water vapor (i.e. vacuum). Humid air degrades film properties due to oxidation accompanied by high wear and increasing coefficients of friction. The present study aims at the further development of sputtered pure MoS2 coatings, extending their applicability to varying environmental conditions by increasing the resistance against humidity. The systematic coating development process is supported by using an experimental Box-Behnken design with variations of the deposition parameters cathode voltage, target/substrate distance, temperature and argon gas pressure. In contrast to common one-factor-at-a-time (OFAT) studies, this approach enables a determination of interactions between deposition process parameters and tribological-mechanical MoS2 film properties. The tribological improvement focuses on a maximization of wear resistance in air and vacuum measured in ball-on-disk experiments. The evaluated mechanical properties are hardness, elastic modulus and residual stresses. These stresses were determined by the substrate curvature method. The study reveals that the residual stress state in the films and the hardness-to-modulus ratio are crucial for their tribological performance in humid air and vacuum environments. After a detailed determination of the relationships between deposition conditions and film properties, some selected microstructural analyses are presented which show that a substantially basal orientation of the lattice has positive effects on wear but also causes anisotropic film properties which result in fissile fracture of the coating if strong shock or point loads occur.
UnivIS-Import:2015-03-09:Pub.2013.tech.FT.FT-KLMEFK.humidi
Keywords: Humidity resistance; MoS2; Residual stress; Unbalanced magnetron sputtering

Hybrider Zusammenhalt - Witzgall, Christian; Wartzack, Sandro (CADFEM Journal, 2015)
UnivIS-Import:2015-10-26:Pub.2015.tech.FT.FT-KLMEFK.hybrid
Keywords: Klebeverbindung; Hybrider Leichtbau

Hybride Strukturen einfach und effizient berechnen - Witzgall, Christian; Kellermeyer, Markus; Wartzack, Sandro (Adhaesion Kleben und Dichten, 2015)

Hybrid Tolerance Representation of Systems in Motion - Heling, Björn; Hallmann, Martin; Wartzack, Sandro (27th CIRP Design Conference, 2017)
Dimensional management deals with the fact that the real geometry of every manufactured part deviates from its ideal shape. To evaluate the effects of these deviations tolerance analysis, which are often based on vectorial models, are carried out. Nevertheless the use of vectorial models has one major disadvantage – they cannot adequately represent form deviations. As a consequence new concepts of representations based on the GPS’ Skin Model have been established. Since the use of Skin Model Shapes (SMS) is time-consuming and does not always offer advantages over vectorial models, the Hybrid Tolerance Representation (HTR) which combines the advantages of vectorial and discretely represented tolerances is introduced in this paper. The HTR is based on a classification of the contact situation of the cinematic chain into lower and higher kinematic pairs. Based in this classification all higher kinematic pairs are going to be represented by SMS whereas lower pairs, are represented by vectors. Besides the simulation of the contact situation of all higher kinematic pairs the coupling of vectorial and discrete geometry representations is a challenge. The practical implementation of the presented method is shown on an X-ray shutter.
Keywords: Tolerance Analysis; Systems in motion; Hybrid Tolerance Representation

Identification of Property Change Impacts Based on Requirements-Oriented, Multi-Criteria Decision Models - Horber, Dennis; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the Design Society, 2022)
As an outcome of the multi-criteria evaluation of different alternatives, product developers receive information on whether the evaluation alternatives meet the demanded property profile. If not, product characteristic and property changes are required, which can have desired and undesired effects. This contribution presents an MBSE-based approach, which extends the relational requirement model by value functions and product properties. Its novelty can be found in the integration of multi-criteria decision models, which are used to improve alternatives based on property change impact analyse
Keywords: decision making; requirements management; characteristics and properties; engineering change; model-based systems engineering (MBSE)

Impact of collaborative space on team work in engineering design education - Fechter, Marius; Kett, Susan; Luft, Thomas; Wartzack, Sandro (DS 84: Proceedings of the DESIGN 2016 14th International Design Conference, 2016)
This paper presents a study investigating the impact of space design on behaviour and creative outcome of team work in learning environments. A dedicated space was especially designed and equipped to facilitate creativity during collaboration. A student course in engineering design was held both in conventional classroom settings and in the newly designed space. The observations and measurements made relating to the two environments are shown and discussed in the paper. The results indicate noteworthy differences that can help to positively influence learning and creativity in future lectures.
Keywords: collaboration; space design; creativity; design education

Impact of the parameter distribution on the predictive quality of metamodels for clinch joint properties - Einwag, Jonathan-Markus; Mayer, Yannik; Götz, Stefan; Wartzack, Sandro (SheMet2025, 2025)
The growing significance of lightweight design, reveals drawbacks of conventional joining processes such as welding, which are known to consume a considerable amount of energy. This fosters the use of mechanical joining processes including clinching. However, the lack of universally applicable design methods results in a cost- and time-intensive design process. The utilization of machine learning methods can overcome these drawbacks. To ensure a reliable clinch joint design, inherent uncertainties of the design parameter such as tool deviations need to be considered in the design process. Varying distributions of design parameters, due to changes in the manufacturing process, can lead to high-computational effort in recalculating the resulting clinch joint properties with numerical simulations. Current metamodel-based methods for consideration of inherent uncertainties within the design parameters do not investigate the transferability of metamodels to different distributions of design parameters, which can lead to incorrect predictions. Therefore, this contribution investigates the performance of several metamodels on differently distributed design parameters. The obtained results indicate that metamodels demonstrate the best performance when training and evaluation distributions are identical and that polynomial regression models perform best on disparate distributions, when trained on uniform distribution
Keywords: Uncertainty; Machine Learning; Mechanical Joining

Implementation And Interpretation Of A Scrap And Failure Oriented Multi-Objective Optimization Considering Operational Wear - Bode, Christoph; Götz, Stefan; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the Design Society, 2023)
The tolerancing of products for manufacturing is usually performed at the end of the design process and the responsibility of the designer. Although components are commonly tolerated to ensure functionality, time-based influences, like wear, that occur during operation, are often neglected. This could result in small amounts of scrap after production, but high quantities of failure during operation. To overcome this issue, this paper presents an approach to perform a multi-objective optimization considering tolerances based on a wear simulation. Thereby, mean shifts serve as optimization variables, while the aim of the optimization is to generate an optimal ratio of scrap to failure. In addition, the optimization results are interpreted and further options for the designer are presented. Moreover, the approach is exemplary applied to a use cas
Keywords: Tolerance representation and management; Optimisation; Simulation; Scrap and failure; Operational wear

Improved Sheet Bulk Metal Forming Processes by Local Adjustment of Tribological Properties - Hetzner, Harald; Koch, Johannes Peter Karl; Tremmel, Stephan; Wartzack, Sandro; Merklein, Marion (Journal of Manufacturing Science and Engineering, 2011)
This paper is focused on a combined deep drawing and extrusion process dedicated to the new process class of sheet bulk metal forming (SBMF). Exemplified by the forming of gearings, combined sheet and bulk forming operations are applied to sheet metal in order to form local functional features through an intended and controlled change of the sheet thickness. For investigations on the form filling and the identification of significant influencing factors on the material flow, a FE simulation model has been built. The FE model is validated by the results of manufacturing experiments using DC04 with a thickness of 2.0 mm as blank material. Due to the fact that the workpiece is in extensive contact to the tool surface and that the pressure reaches locally up to 2500 MPa, the tribological conditions are a determining factor of the process. Thus, their influence is discussed in detail in this paper. In the first instance, different frictional zones having a distinct effect on the resulting material flow are identified and their effect on improved form filling is demonstrated. Subsequently, a more comprehensive methodology is developed to define tribological zones of forming tools. For this, a system analysis of the digital mock-up of the forming process is performed. Besides friction, other relevant aspects of forming tool tribology like contact pressure, sliding velocity, and surface magnification are considered. The gathered information is employed to partition the tools into tribological zones. This is done by systematically intersecting and re-merging zones identified for each of the criterion. The so-called load-scanning test allows the investigation of the friction coefficient in dependence of the contact pressure and possible loading limits of tribological pairings. It provides an appropriate tribological model test to evaluate tribological measures like coatings, surface textures and lubricants with respect to their targeted application in particular zones. The obtained results can be employed in the layout of further forming processes to reach the desired process behavior. This can be, for example, an improved form filling, less abrasive wear and adhesive damage or lower forming forces, respectively tool load for an improved durability of the die.
UnivIS-Import:2015-03-09:Pub.2011.tech.FT.FT-KLMEFK.improv
Keywords: load-scanning test; material flow; sheet bulk metal forming; tribology

Improving Products by Combining Usability and Emotions - Buker, Tina; Miehling, Jörg; Wartzack, Sandro (Design Methodology for Future Products, 2022)
User-friendly and successful products usually emerge when pure functionality meets good usability as well as an emotional and aesthetic design. Modern theoretical approaches consider all of those three aspects as equally important. In practice, however, they are often still treated independently from one another. Thus, neither positive nor negative interdependencies can be taken into account. This chapter tries to close this gap by examining the relationship of usability and emotions and introducing the idea of dual user integration that aims for combining both aspects. A concrete approach to balance both aspects focusing on emotional impressions and physical capacities of the user is presented to make dual user integration applicable. This proactive approach is called Application for Computer-Aided Design of Emotional impressions and Physical capacities (ACADE+P) and consists of three main steps: (1) user/product description, (2) product evaluation and (3) data-based derivation of quantitative recommendations for design improvements. In addition to the general framework, the specific workflow of the method including an analysis and synthesis phase is explained in detail.<br

IMU-based direct analytical joint center identification method for OpenSim – A proof of concept - Wechsler, Iris; Wartzack, Sandro; Koelewijn, Anne; Miehling, Jörg (29th Congress of the European Society of Biomechanics, 2024)

IMU-based identification method for joint axes in OpenSim – a proof of concept - Wechsler, Iris; Wartzack, Sandro; Koelewijn, Anne; Miehling, Jörg (29th Congress of the European Society of Biomechanics, Edinburgh., 2024)

Individualized vs. Population-based Musculoskeletal Simulation for Medical and Product Engineering - Miehling, Jörg (27th Congress of the European Society of Biomechanics, 2022)
INDIVIDUALIZED VS. POPULATION-BASED MUSCULOSKELETAL SIMULATION FOR MEDICAL AND PRODUCT ENGINEERING Jörg Miehling Engineering Design, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Germany Background Musculoskeletal simulations hold high potentials by revealing the processes and inner strain conditions of the human body for a wide range of areas. The computed physiological parameters can give insights for the engineering of medical and rehabilitation technology, exoskeletons, mobility products and sports equipment [1]. For reliable and physiological simulation results, a musculoskeletal model suitable for the application as well as a way to measure or predict the human motion and if applicable the interaction with the environment or product are necessary [2]. The conventional approach uses observations from optical marker tracking. This is still the gold standard for motion measurement. However, it requires preparation, data acquisition and post-processing effort. More importantly, often just anthropometric scaling is performed based on the marker data to adapt a generic model to a specific person. Other crucial factors such as muscle strength or mobility are regularly disregarded. Recent Advances Patient-specific models, however, mostly rely on 3D MRI/CT data. Using parameters extractable from the imaging data, a generic model is adapted to the specific patient, usually in a restricted area of interest [3]. These models are usable for observational and predictive simulations, but only in very specific situations, such as for surgery planning. In most other applications, it is not feasible to access the necessary data, not least due to ethical issues as well as the time and cost involved. Population-based approaches bridge the gap towards predictive simulations even further. Modelling relies on empirical population data to adapt a generic model to a desired statistical representative of the population. Based on this direction, a procedure to create consistent groups of musculoskeletal models across different domains (e.g. range of motion, strength) was set up [4]. Such a model group was used in the ergonomic optimization of bicycles and skiffs [2]. These examples as well as the ergonomic optimization of trikes [5] indicate the strength of predictive musculoskeletal simulations for (bio)engineering applications. In order to increase data consistency between computer-aided-design applications and human models, we work on a computer-aided-ergonomics tool integrating user, product/environment and interaction models by a feature-based description of physical interactions [6, 7]. Current research also focuses on a co-simulation model integrating a musculoskeletal model with exoskeleton and power tool models to optimize support systems [8]. Future directions Our goal is to provide methods for the assessment of human behavior in order to support (bio)engineering processes. We work on tracking methods integrating multimodal motion measurement data of novel sensor technology leading to more efficient and accessible workflows. We individualize musculoskeletal human models in multiple domains considering subject-specific kinematic and dynamic movement capabilities. Beyond, the extension of human models with sensorimotor regulation offers potentials to deepen the understanding of bodily processes in order to increase the insights of biomechanical simulation results. Moreover, we address a methodology integrating finite element and musculoskeletal models as well as the phenomenological characterization of human behavior for proactive simulation of user-product-interactions. References 1. Wartzack et al., Proc. ICED19, 3989-3998, 2019. 2. Miehling, VDI, 445, 2018. 3. Scherb et al., CMBBE Conf., 2021. 4. Miehling, Comput. Methods. Biomech. Biomed. Eng., 22(15):1209-1218, 2019. 5. Meißner et al., Konstruktion, accepted. 6. Wolf et al., IISE Trans. Occup. Ergon. Hum. Factors, 2021. 7. Wolf et al., Ergonomics, 63(11):1442-1458, 2020. 8. Molz et al., CMBBE Conf., 2021. Acknowledgements This work was (partly) supported by the Deutsche Forschungs-gemeinschaft (DFG, German Research Foundation) under Grant SFB 1483–Project-ID 442419336. This work was (partly) supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Grants WA 2913/31-1, WA 2913/41-1 and MI 2608/2-1. The author greatfully acknowledges Prof. Sandro Wartzack, the group members and all collaborators, who contributed to this work. Jörg Miehling is currently principal investigator and research division leader at the Chair of Engineering Design, FAU Erlangen-Nürnberg, Germany. He completed his doctorate in 2018. His research focuses on musculoskeletal modelling and simulation, computer-aided-ergonomics and user-centered-design. He successfully obtained research grants from the German Research Foundation (DFG), including two projects in a Collaborative Research Centre (CRC/SFB), one of the most competitive and prestigious funding sources in Germany. He is author of more than 50 publications in peer-reviewed journals, book chapters and contributions to international and national conferences.<br
Keywords: MUSCULOSKELETAL SIMULATION; MEDICAL ENGINEERING

Influence of bias voltage and layer thickness variation on mechanical properties and tribological behavior of a-C:H:W multilayer coatings - Weikert, Tim; Tremmel, Stephan (Proceedings of the 17th Nordic Symposium on Tribology - NORDTRIB 2016, 2016)
Metal-doped hydrogenated amorphous carbon (a‑C:H:Me) coatings are widely used in industrial applications owing to low friction and high wear resistance. In higher loaded applications like forming processes, especially tungsten-modified hydrogenated amorphous carbon (a‑C:H:W) coatings have proven their worth. Interestingly, several experimental studies have shown that modification of the coating architecture, such as multilayered structures, can result in further advantageous coating properties. In the present study, approximately 2 µm thin a‑C:H:W multilayer coatings were deposited in a combined PVD/PACVD coating process. Alternating soft and hard a‑C:H:W layers were generated by means of alternating bias voltage. The bias voltage and the deposition time or the number of layers for the alternating layers, respectively, were varied according to an experimental Box-Behnken design, allowing a systematic and statistical evaluation of the relationship between deposition parameters and coating properties. Coatings’ characterization revealed significant influences of the bias voltages on the coatings’ mechanical properties and tribological behavior whereas the deposition time showed only minor effects. Moreover, a special type of multilayered structure was generated inspired by the internal structure of a marine sponge’s anchor spicule. This variant showed promising mechanical and tribological properties accentuating its use in applications with higher loads.
Keywords: diamond-like carbon; a-C:H:W; multilayer coatings

Influence of geometrical parameters of conic pin structures in thermoplastic composite/steel hybrid joining - Popp, Julian; Zirngibl, Christoph; Schleich, Benjamin; Wartzack, Sandro; Drummer, Dietmar (Materials Research Proceedings, 2023)
Hybrid parts consisting of continuous fiber reinforced thermoplastic (CFRT) and steel components offer promising potential in lightweight construction. In this approach, the joining operation poses the major challenge due to different physical and chemical properties of both materials. This paper studies a joining method in which conical pin structures, protruding from the surface of the metal component, are inserted into the locally heated CFRT component to create a form fitting joint. The aim is to identify and quantify the influence of the parameters pin height and pin head diameter on the mechanical performance in single lab shear and cross head normal experiments. Based on the results it can be shown, that both an increased pin height and head diameter are beneficial under shear load in means of increased maximum load capacity while under normal load only an increased head diameter has clear benefits. Those effects are led back to the geometrical properties and the resulting stress distributions in the joining area.
CRIS-Team Scopus Importer:2023-04-28
Keywords: Composite; Hybrid Manufacturing; Joining

Influence of Laminate Parameter and Draping Variations on Locally Reinforced Composite Parts - Freitag, Stephan; Götz, Stefan; Wartzack, Sandro (Procedia CIRP, 2024)
Fibre-reinforced plastics (FRP) are a modern high-tech material and offer enormous lightweight potential. However, the material properties of composite materials lead to new challenges in the design and manufacturing process. Methods considering the anisotropic material behaviour during the design phase have been developed recently, leading to an optimised nominal laminate layout that often consists of a base laminate with local reinforcement patches. Yet, the laminate parameters suffer from variations during the manufacturing process. Additionally, deviations from the nominal fibre angles occur when draping the laminate of curved parts and interact with the occurring parameter variations. So far, the mentioned variations are insufficiently considered in combination with draping and reinforcement patches in the design of FRP parts. In order to overcome this shortcoming, a novel simulation approach for the draping of reinforcement patches is presented, which allows a more accurate prediction of fibre angles after adding random variations and draping deviations. The novelty of this approach lies in the consideration of variations in the draping simulation and their influence on the resulting draping deviations. It also enables further investigations, such as the influence on the draping deviations if the draping starting point is not the centre of the patch. The influence of different parameter variations on the component quality is then investigated by performing structural analyses of the part using the results from the draping simulatio
Keywords: Fibre-reinforced plastics; Draping simulation; Local reinforcement; Design of ExperimentsTolerancing

Influence of laser generated micro textured coated tool surfaces on dry deep drawing processes - Tenner, Jennifer; Häfner, Tom; Rothammer, Benedict; Krachenfels, Kim; Zhao, Rong; Schmidt, Michael; Tremmel, Stephan; Merklein, Marion (Dry Metal Forming Open Access Journal, 2018)
The idea of sustainability and resource conservation promotes the development of energy-efficient and low-emission production processes. A lubricant-free sheet metal forming process is considered as one of these environmentally friendly production technologies. Metal forming processes without conventional lubricants shorten process steps and reduce additional costs, such as removal of residual lubrication from the workpiece after forming. In order to realize such a dry forming process and effectively control the material flow, amorphous carbon coatings were applied to the tool surfaces and a brushing process was carried out as a surface finishing process for roughness adjustment. Laser generated micro features on the surface should make an effective contribution to local friction adaptation. The transferability of strip drawing test to strip bending rotation test was successfully demonstrated by dry and oiled blank reference tests. The first modification of the tool sided surface was achieved by applying ta-C and a-C:H layers. The influence of the coatings on the tribological behaviour was determined in strip drawing tests for DC04 and AA5182. Additional friction adaptation is made possible by the fine and flexible laser based micro texturing of the coated tool surface. Experiments were carried out with different coverage and depth of the laser generated features in order to analyze the tribological influence. Flat and deep features with a degree of coverage of 20 %, 35 % and 50 % are considered in order to analyze the factors influencing their tribological behavior. Compared to ta-C coated references, it can be seen that micro features on the ta-C coated tool surface causes a friction reduction for DC04, independent of the features depth. However, deep laser generated features in particular lead to an increase in friction for AA5182, so that this could potentially lead to a selective local increase in friction in the flange area. For the transferability of the tribological system from the flat application case to a curved tool surface, the basics for laser based texturing of cylinder surfaces are illustrated. The limits of the holographic beam shaping technology used for this are demonstrated.
Keywords: Dry Deep Drawing; Tribology; Carbon Based Coatings; Laser Based Texturing

Influence of layer thickness variations on the structural behaviour of optimised fibre reinforced plastic parts - Franz, Michael; Schleich, Benjamin; Wartzack, Sandro (Procedia CIRP Volume 85, 2019)
Fibre reinforced plastics (FRP) are considered as a modern high-tech material. The enormous lightweight potential, especially of carbon fibre reinforced plastics, accelerates its spreading in many industrial applications. However, as good as the lightweight potential of FRP is, as difficult is the optimal use in products because of its anisotropic material properties. Recently, methods considering the anisotropic material behavior during the product development process have been developed. These result in optimized nominal laminate layouts with defined laminate parameters like fibre orientation, ply thickness and ply stack-up order. Yet, during the manufacturing process, variations of these parameters, compared to the nominal design, occur. The variations result in asymmetric laminates, which causes couplings in the stiffness matrix and consequently undesired deformations. The effects of varying laminate design parameters have so far mainly been investigated with focus on manufacturing activities. However, to support the design engineer in considering the influence of varying laminate parameters on product behavior, this paper studies the effects on the structural behavior of optimized FRP-parts. The main novelty and contribution of the paper can be found in providing a new approach for the consideration of uncertainties in the ply thickness on FRP parts with optimized fibre layout. For this purpose, sensitivity analyses are performed with the aim of investigating the importance of the parameters on the structural behavior. With this knowledge, the product developer is able to distinguish between critical and non-critical laminate parameters and consider their variations in the product development process as early as possible.<br
Keywords: Fibre reinforced plastic; Product development; Structural analysis; Tolerancing

Influence of metal gear tooth geometry on load and wear within metal-polymer gear pairs - Rohrmoser, Andreas; Bode, Christoph; Schleich, Benjamin; Hagenah, Hinnerk; Wartzack, Sandro; Merklein, Marion (Applied Sciences, 2022)
Gear pairs made of the material pairing metal-polymer provide advantages, such as a reduced weight, beneficial damping properties and the possibility to be operated in dry running conditions. However, the service life of the pairing is limited due to wear. The properties of the metallic gearing have a significant influence on the wear behavior of the material pairing. From previous investigations, the influence of the surface topography and the flank hardness of the metal pinion is known. With regard to resource saving and efficient manufacturing of the metal pinion, cold forging offers benefits. Through cold forging, metallic gears for the material pairing can be produced ready-to-use in a process suitable for serial production. In order to enable manufacturing by extrusion, the application of gear radii is necessary. The gear radii significantly affect the extrusion process and the achievable gear properties. However, the influence of gear radii on wear within the metal-polymer material pairing has not yet been investigated. Within this contribution, the influence of the gear radii on the contact behavior as well as the resulting local load and wear of the tooth flank is determined. For this purpose, wear tests with aluminum (AlMgSi1) and steel (16MnCr5) gears with different gear radii within the pairing with polyamide (PA66) gears were performed. It has been shown that the local wear of the tooth flank can be attributed to the local load and that adjusted gear radii lead to a varying load and wear of the metal and polymer gears. Based on the findings, functional relationships regarding the choice of gear radii and the wear behavior are derived which can be applied in the design of cold forged gears.
Created from Fastlane, Scopus look-up
Keywords: Gear; Metal; Polymer; Tooth contact; Tooth geometry; Wear

Influence of microstructure shape, non-Newtonian lubricant and thermal effects on microstructured surfaces in rolling/sliding EHL contacts - Weschta, Martin; Tremmel, Stephan; Wartzack, Sandro (STLE 70th Annual Meeting & Exhibition, 2015)
UnivIS-Import:2015-10-26:Pub.2015.tech.FT.FT-KLMEFK.influe
Keywords: EHL Film Geometry; Surface Modification; Non-Newtonian Lubricant; Thermal Effects

Influence of process variations on clinch joint characteristics considering the effect of the nominal tool design - Zirngibl, Christoph; Götz, Stefan; Wartzack, Sandro (Proceedings of the Institution of Mechanical Engineers Part E-Journal of Process Mechanical Engineering, 2024)
Focusing on upcoming challenges in lightweight design, such as increasing emission targets or novel multimaterial connections, versatile applicable and environmentally friendly production technologies are crucial. In this context, mechanical joining technology clinching offers a fast and energy-efficient procedure for assembling sheet metals, being a proper alternative to established joining methods, such as spot welding. However, the design of clinch points is a challenge, which is partly supported by numerical or data-based approaches for optimal tool dimensions assuring proper joint characteristics. While this is usually done for an ideal environment, real joining processes are characterized by multiple inevitably varying parameters, e.g. of the material, which have a significant impact on the quality of clinch points. Therefore, this contribution addresses the current gap by analyzing the effect of parameter variations or uncertainties on the resulting joint characteristics and studying the impact of the nominal tool design. Thus, an efficient meta-model-based variation simulation procedure is proposed and used for analyzing the effect of different tool design configurations and variation scenarios. Based on the results, it was found that varying process parameters have a strong impact on the resulting joint characteristics, whereby the effect significantly depends on the nominal tool design. This reveals the potential for a robust tool design and implies that the nominal tool design and the tolerancing of parameters should be done simultaneously for a reliable virtual joining point design without extensive iterations and physical tests.<br
Keywords: Clinching; joining by forming; uncertain process parameters; variation analysis; metamodeling; tolerance design

Influence of the engine oil additives ZnDTP and MoDTP on the tribological behavior of hydrogenated and not hydrogenated amorphous carbon coatings - Schulz, Edgar; Wackerbauer, Veit; Musayev, Yashar; Tremmel, Stephan; Hosenfeldt, Tim; Wartzack, Sandro; Meerkamm, Harald (Proceedings of the 9th International Conference THE"A" coatings, 2011)
UnivIS-Import:2015-04-16:Pub.2011.tech.FT.FT-KLMEFK.influe

Influence of ultrasonic vibration on the shear formability of metallic materials - Michalski, Markus; Lechner, Michael; Gruber, Micha; Merklein, Marion (CIRP Annals - Manufacturing Technology, 2018)
The flow stress reduction of metallic materials due to superimposed ultrasonic vibration is an intensively researched phenomenon. So far, however, only a few studies have analysed the vibrational influence on forming limits. Existing findings are inconsistent, suggesting both a formability extension and a decrease. Ultrasonic-assisted shear tests constitute a novel experimental approach for the fundamental investigation of predominant cause–effect–relationships. The test results reveal a distinct correlation between the application of ultrasonic vibration and earlier material failure. This effect is attributed to enhanced crack initiation and propagation caused by localised stress and strain concentration as well as intermittent high strain rates.
LFT Import::2019-07-29 (2298)
Keywords: Failure; Forming; Ultrasonic

Influence of varying sheet material properties on dry deep drawing process - Krachenfels, Kim; Rothammer, Benedict; Zhao, Rong; Tremmel, Stephan; Merklein, Marion (IOP Conference Series: Materials Science and Engineering, 2019)
Deep drawing is one of the most important processes in sheet metal forming. Conventionally, lubricants are used to reduce friction and wear. Demands for increased sustainability, environmental protection and resource efficiency motivate the realization of lubricant-free forming processes. The direct contact between tool and workpiece during dry deep drawing results in changed tribological conditions, which cause an increase in friction and wear. Friction-reducing surface modifications of the tool such as carbon based coatings are being developed for the adaptation of the tribological conditions. The aim of this work is the simulation-based analysis of the stress spectrum for varying sheet properties for the qualification of wear-reducing surface modifications for a wide range of applications. By a simulation model for a rectangular cup, the influence of different batches of steel and aluminum materials with varying friction coefficients and mechanical properties is investigated within the framework of variant simulations. The tribological conditions in the simulation are described on the basis of friction coefficients from the strip drawing test. From the simulation results, the applicability of surface modifications for dry deep drawing is being evaluated depending on the sheet specific properties.<br

Inner marginal strength of CAD/CAM materials is not affected by machining protocol - Lubauer, Julia; Belli, Renan; Schünemann, Fernanda H.; Matta, Ragai; Wichmann, Manfred; Wartzack, Sandro; Völkl, Harald; Petschelt, Anselm; Lohbauer, Ulrich (Biomaterial Investigations in Dentistry, 2021)
Purpose Here we aimed to compare two machining strategies regarding the marginal strength of CAD/CAM materials using a hoop-strength test in model sphero-cylindrical dental crowns, coupled with finite element analysis. Materials and Methods Five CAD/CAM materials indicated for single posterior crowns were selected, including a lithium disilicate (IPS e.max® CAD), a lithium (di)silicate (Suprinity® PC), a polymer-infiltrated ceramic scaffold (Enamic®), and two indirect resin composites (Grandio® Blocs and Lava™ Ultimate). A sphero-cylindrical model crown was built on CAD Software onto a geometrical abutment and machined using a Cerec MC XL system according to the two available protocols: rough-fast and fine-slow. Specimens were fractured using a novel hoop-strength test and analyzed using the finite element method to obtain the inner marginal strength. Data were evaluated using Weibull statistics. Results Machining strategy did not affect the marginal strength of any restorative material tested here. Ceramic materials showed a higher density of chippings in the outer margin, but this did not reduce inner marginal strength. IPS e.max® CAD showed the statistically highest marginal strength, and Enamic® and Lava™ Ultimate were the lowest. Grandio® Blocs showed higher performance than Suprinity® PC. Conclusions The rough-fast machining strategy available in Cerec MC XL does not degrade the marginal strength of the evaluated CAD/CAD materials when compared to its fine-fast machining strategy. Depending on the material, resin composites have the potential to perform better than some glass-ceramic materials.
Keywords: CAD/CAM; strength; finite element

Innovative Tribological Systems in Sheet Metal Forming - Revolution in the Press Shop? - Andreas, Kolja; Tenner, Jennifer; Vierzigmann, Ulrich; Merklein, Marion; Tremmel, Stephan; Zhao, R. (Proc. 11th Int. Conf. THE "A" Coatings in Manufacturing Engineering, 2014)
LFT Import::2019-08-05 (2048)

Integrated approach enabling robust and tolerance design in product concept development - Götz, Stefan; Kirchner, Philipp; Schleich, Benjamin; Wartzack, Sandro (Design Science, 2021)
Along with the ever-increasing customer demands, early consideration of variation in terms of robust design is important to avoid expensive iterations in the product development. However, existing methods are detached from the development process and can therefore only be applied at a late stage or only with comprehensive expert knowledge. Especially in the concept stage, where the geometry of a product is not yet defined and the optimisation potential is high, effective solution proposals for systematic consideration of variation are lacking. Therefore, this paper describes a new integrated approach facilitating robust and tolerance design in the concept stage. The novelty of the approach using ontologies and graph-based visualisation is the close linkage of product development and tolerance knowledge, which allows automation and helps to avoid time- and cost-intensive iteration loops. As a result, a robust and tolerance-compliant concept design, an initial qualitative tolerance specification and instructions for the further tolerancing process are already available at the end of the concept stage. The applicability and the benefits of the approach are illustrated by representative case studies and a user study allowing a critical comparison between the conventional, mostly subjective procedure and the presented approach.
Keywords: robust; designtolerance; designconcept; designgraphontology

Integrated Tolerance and Fixture Layout Design for Compliant Sheet Metal Assemblies - Rezaei Aderiani, Abolfazl; Hallmann, Martin; Wärmefjord, Kristina; Schleich, Benjamin; Söderberg, Rikard; Wartzack, Sandro (Applied Sciences, 2021)
Part tolerances and fixture layouts are two pivotal factors in the geometrical quality of a compliant assembly. The independent design and optimization of these factors for compliant assemblies have been thoroughly studied. However, this paper presents the dependency of these factors and, consequently, the demand for an integrated design of them. A method is developed in order to address this issue by utilizing compliant variation simulation tools and evolutionary optimization algorithms. Thereby, integrated and non-integrated optimization of the tolerances and fixture layouts are conducted for an industrial sample case. The objective of this optimization is defined as minimizing the production cost while fulfilling the geometrical requirements. The results evidence the superiority of the integrated approach to the non-integrated in terms of the production cost and geometrical quality of the assemblies.<br
Keywords: tolerance-cost optimization; fixture layout optimization; variation simulations; non-rigid assemblies

Integrating Digital Twins and Cyber-Physical Systems for Flexible Energy Management in Manufacturing Facilities: A Conceptual Framework - Rolofs, Gerrit; Wilking, Fabian; Götz, Stefan; Wartzack, Sandro (Electronics, 2024)
This paper presents a conceptual framework aimed at integrating Digital Twins and cyber-physical production systems into the energy management of manufacturing facilities. To address the challenges of rising energy costs and environmental impacts, this framework combines digital modeling and customized energy management for direct manufacturing operations. Through a review of the existing literature, essential components such as physical models, a data platform, an energy optimization platform, and various interfaces are identified. Key requirements are defined in terms of functionality, performance, reliability, safety, and additional factors. The proposed framework includes the physical system, data platform, energy management system, and interfaces for both operators and external parties. The goal of this framework is to set the basis for allowing manufacturers to reduce energy consumption and costs during the lifecycle of assets more effectively, thereby improving energy efficiency in smart manufacturing. The study highlights opportunities for further research, such as real-world applications and sophisticated optimization methods. The advancement of Digital Twin technologies holds significant potential for creating more sustainable factorie
Keywords: Digital Twin; energy system; model-based systems engineering; simulation; CPPS; energy management; EMS

Integrating Machine Learning in Digital Twins by utilizing SysML System Models - Wilking, Fabian; Sauer, Christopher; Schleich, Benjamin; Wartzack, Sandro (17th Annual System of Systems Engineering Conference (SOSE), 2022)

Integrating optical 3D measurement techniques in pipe bending: a model-based approach minimising waste by deriving real functional design behaviour - Katona, Sebastian; Lušić, Mario; Koch, Michael; Wartzack, Sandro (Procedia CIRP, 2016)
Due to springback, deviations compared to the designed ideal modal occur during pipe bending processes. With quality control gauges no quantitative statements can be made regarding the process stability. The components are either good or bad and no production trends can be determined. This leads to high scrap rates and in addition, the real performance of the produced components may differ from the target behaviour of the initially designed CAD model. As addressed within this contribution, with integrating optical 3D measuring systems into the bending process, the actual state can be detected continuously. This enables to give feedback to the bending device for automatically readjust of bending parameters and thus prevent producing defective components. Moreover, the digitalisation of the actual contour allows a parametric correction of the designed CAD model, whereby the functional behaviour can be closer to reality within simulation models.
Keywords: In-process measurement; bending; springback; computer aided design (CAD); simulation; real function design behaviour

Integrating real geometry models into product simulations: an approach of knowledge-based process - Katona, Sebastian; Koch, Michael; Wartzack, Sandro (Proceedings of the 14th International Design Conference DESIGN 2016, 2016)
Simulation driven product development is state of the art to insure that the desired characteristics in use behave as requested without performing a time-consuming testing using expensive prototypes. To achieve the aim of realistic and confidential results within this product simulations, a tremendous afford (i.e. when taking different non-linearities into account, like material behavior, contact situations, large deflections etc.) is necessary. Conflicting to this, the ideal CAD-model is always used for the analysis, despite knowing the effect, that every manufactured component shows differences to its ideal geometry. Within this paper an approach of a knowledge-based process to integrate real geometry data into product simulations is given. Furthermore, different methods for preparation of the simulation models are represented.
Keywords: CAx; computer aided design (CAD); product development; structural analysis; knowledge based engineering

Integrating The Mechanical Domain Into Seed Approach - Dworschak, Fabian; Kügler, Patricia; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the 22nd International Conference on Engineering Design (ICED19), 2019)
Data-driven technologies have found their way into all areas of engineering. In product development they can accelerate the customization to individualized requirements. Therefore, they need a database that exceeds common product data management systems. The creation of this database proves to be challenging because in addition to explicit standards and regulations the product design contains implicit knowledge of product developers. Hence, this paper presents an approach for the semantic integration of the engineering design (SeED). The goal is an automated design of an ontology, which represents the product design in detail. SeED fulfils two tasks. First, the ontology provides a machine-processable representation of the products design, which enables all kind of data-driven technologies. Among other representations, the ontology contains formal logics and semantics. Accordingly, it is a more comprehensible solution for product developers and knowledge engineers. Second, the detailed representation enables discovering of intrinsic knowledge, e.g. design patterns in product generations. Consequently, SeED is a novel approach for efficient semantic integration of the product d
Keywords: Semantic data processing; Engineering ontologies; Engineering data acquisition; Implicit knowledge integration

Integration elastischer Deformationen in die statistische Toleranzanalyse bewegter Systeme mittels Metamodellen - Sprügel, Tobias; Walter, Michael (Summer School Toleranzmanagement: Beiträge zur 1. Summer School, 2013)
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.integr_1
Keywords: Statistische Toleranzanalyse; Metamodelle; bewegte technische Systeme; KNN; Kriging; RSM

Integration kommerzieller Toleranzanalysesoftware in die Toleranz-Kosten-Optimierung - Haigis, Natalja; Hallmann, Martin (Summer School Toleranzmanagement - Beiträge zur 4. Summer School - September 2020, 2020)

Integration of manufacturing constraints into multi-material topology optimization - Kopatsch, Jan; Polzer, Markus; Bartz, Marcel; Wartzack, Sandro (DS 133: Proceedings of the 35th Symposium Design for X (DFX2024), 2024)
Multi-material topology optimization (MMTO) offers lightweight design potential compared to single-material topology optimization (SMTO). For integrating restrictions of manufacturing processes into a MMTO ordered SIMP model, a mapping scheme is used to assign them only to the relevant material sections. By filtering and projection of the design variables, manufacturing constraints are implemented without considerable increase in optimization effort. Optimization results are compared by objective function values, convergence and effects of manufacturing constraints. The improved manufacturability of the optimization results can be achieved with only slight reduction in the objective function value, which is due to the restriction of the design space introduced by manufacturing constraints.<br
Keywords: Topology optimization; Multi-material; Ordered SIMP; Manufacturability; Heaviside projection method

Integration of musculoskeletal and model order reduced FE simulation for passive ankle foot orthosis design - Scherb, David; Steck, Patrick; Wartzack, Sandro; Miehling, Jörg (27th Congress of the European Society of Biomechanics, 2022)
Introduction Motor disorders are caused by nerve damages that affect the control of muscles resulting in paralysis or paresis [1]. A common example is the paralysis / paresis of the lower leg muscles (e.g. caused by stroke) leading to a pathologic gait, so called foot drop syndrome [2]. For the treatment of this disease, technical devices are increasingly used, like ankle foot orthoses (AFOs). There are two distinguishing types of AFOs. The first ones are active AFOs that are mainly driven by motors and actuation algorithms. However, there are issues with weight and power supply. The second type of AFOs, passive AFOs, on the other side have a low weight, are mobile and do not use external power supply, but lack to provide sufficient support in the stance phase of gait. New, innovative designs, however, prove to be able to address this problem [3]. Therefore, we decided to develop a new passive AFO design that is provided with fiber-reinforced composites (FRCs) [4] for simultaneously maximizing the stiffness of the stressed areas during load phases while keeping the design lightweight. In order to ensure a suitable support of the human gait behaviour, a model order reduced finite element model (MOR-FEA) [5] of the AFO is linked with a musculoskeletal human model (MHM) [6] (Fig.1) Methods To realize the new AFO, in the first step the basics for the further work had to be compiled. Thus, the conceptual design of the orthosis was developed using methods of engineering design. The main requirement was that the AFO is capable of supplying different support in different directions during gait. Furthermore, this required support in the gait phases had to be determined. For this purpose, healthy subjects are recorded in gait laboratory and their muscle activation is computed with MHMs. Afterwards, the muscles are weakened according to the condition in foot drop and a supportive torque is applied to the models. The torque was applied as a reserve actuator and adjusted in such way that the muscle activation shall remain the same as in healthy condition. Results A conceptual design is found that is able to detect different phases during gait. By triggering a coupling, movement of the ankle can either be blocked or allowed. Additionally, a ratchet clutch mechanism is controlled to load and unload the force-generating structures, which results in the supportive torques during the gait. In the stance phase of gait the most support from the AFO is required. The required quantitative supportive torque depends on the condition of the patient. Patients with less remaining force capability in the lower leg muscles require more support than patients with more remaining force capability. The resulting muscle activations can be decreased by applying more support torque until the muscle activations of the non-paralyzed muscles are similar to the corresponding ones of healthy subjects for all diseased conditions. Discussion The design concept is characterized by the possibility to support all phases during gait. The main criteria for a successful application is the design of the force generating structure. Together with the simulated supportive torques, which mainly match the previous expectations, the development of the method to link the MOR-FEA with MHMs can be approached in the next step to reach an agreement between supplied force and gait behaviour of the patients. In order to enable an evaluation of the simulated results and generated method, a validation with a manufactured prototype of the AFO is planned. References 1. Younger, Lippincott Williams & Wilkins, 1999. 2. Stewart, Pract Neurol, 3: 158–169, 2008 3. Collins, et al., Nature, 7555: 212–215, 2015 4. Völkl, et al., Composite Structures: 359–367, 2018 5. Schilders, et al., Springer Berlin Heidelberg, 2008. 6. Miehling, et al., Biosystems & Biorobotics: 219–227, 2018. Acknowledgements This work was supported by the German Research Foundation (DFG) under Grant WA 2913/43-1 and MI 2608/2-1.<br

Integration of product development data for further ontological utilization - Pickel, Jessica; Bickel, Sebastian; Götz, Stefan; Wartzack, Sandro (DESIGN 2024, 2024)
The amount of data within the product development process requires a structured approach to coordinate them. Knowledge management solutions, such as ontologies, are a suitable way of linking data and representing semantic relationships. However, making all relevant data usable to ensure their target-oriented application is still a challenge. Thus, this contribution presents an approach to identify and classify heterogeneous data in product development. Besides this single ontology approach, interface solutions for data integration into an ontology are proposed.<br
Keywords: ontology; product development; data management; interface solution

Integration of robust and tolerance design in early stages of the product development process - Götz, Stefan; Schleich, Benjamin; Wartzack, Sandro (Research in Engineering Design, 2020)

Integration of structural optimization in the engineering design process - Stangl, Thomas; Pribek, Michael; Wartzack, Sandro (Proceedings of the DESIGN 2014 13th International Design Conference, 2014)
Structural optimization enables the product developer to compute a lightweight design proposal of a considered component during the design process. If topology optimization is integrated as early as possible in the product development process, the design engineer will act more and more frequently as a simulation engineer. To support the product developer to use topology optimization successfully in a methodical way, the paper focuses on the development of an extended design guideline during a design study.
Keywords: topology optimization; CAE; CAD; initial design proposal; design methodology

Integration of Universal Design principles into early phases of product design - a case study. - Kett, Susan; Wartzack, Sandro (Proceedings of the 20th International Conference on Engineering Design (ICED 15) Vol 9: User Centred Design - Design of Socio-Technical Systems, 2015)
Universal design (UD) is a strategy for designing societal and individual living environments. We outline how its generic guidelines need more concretization to be applicable to product development processes. Although the value of UD is widely known, its potentials are often still left unused. This paper’s contribution is to bring UD theory into product development practice by extending the processes that are currently used. Therefore, an appropriate application scenario in mobility and daily needs is proposed. It is proven that this area affects a wide range of users with different requirements and thus has great value for UD. By using the example of a shopping aid, several approaches in creativity can be used in the early phases of product design. Two exemplary methodologies are presented to demonstrate UD integration. We outline that research success can be met in multiple ways. Among other things, we show the integration of UD into systematic product design and the controllability of its value in an ex-ante and accompanying way. Within this process, the holistic view of users will be extendable, e.g. taking sociological, psychological or cultural aspects into account.
Keywords: Design for Life; Inclusive design; Design methodology; Early design phases

Integrierte Gestaltoptimierung für die Produktentwicklung - Wartzack, Sandro; Stangl, Thomas (Konstruktion, 2013)
UnivIS-Import:2015-03-09:Pub.2013.tech.FT.FT-KLMEFK.integr
Keywords: Formoptimierung; CAD; Rückführung

Integrierte Gestaltoptimierung für die Produktentwicklung - Wartzack, Sandro; Stangl, Thomas (Zeitschrift für wirtschaftlichen Fabrikbetrieb, 2013)
Keywords: Formoptimierung; CAD; Rückführung

Interactive immersive engineering system for distant collaboration - Fechter, Marius; Damgrave, Roy Gerhardus Johannes; Wartzack, Sandro (Proceedings of the 20th International Conference on Engineering Design (ICED15), 2015)
Complex products consisting of various components are designed in collaboration of multi-disciplinary engineering teams with different expertise. Expert groups involved in the development process are possibly based at geographically distributed locations. The purpose of this contribution therefore is the development of a framework, enhancing the quality of communication and facilitating the exchange of information and expertise in engineering projects over distance. This framework provides the capability to visualise a product model and the avatars of distant people in one shared immersive virtual environment. Furthermore the integration of product information exceeding the pure geometry and features for direct modification of the visualised product are achieved through the connection to CAD software. The intuitive interaction interface utilises hand gestures based on normal physical interaction with real objects. Being able to see both the 3D model and the other participant in one shared virtual environment creates a natural communication and interaction process, without being distracted by new communication or interaction methods forced by the technology.
UnivIS-Import:2015-10-26:Pub.2015.tech.FT.FT-KLMEFK.intera
Keywords: Collaborative Design; Communication; Human-Computer Interaction; Virtual Reality

Interconnected Tolerancing Activities and the Role of Key Characteristics - Horber, Dennis; Götz, Stefan; Wartzack, Sandro (Research in Tolerancing, 2024)
Products are nowadays characterized by rising complexity, so that companies need to adapt their development processes to resulting challenges. Transferring this need for adaption to the tolerancing domain, new approaches are expected to enable companies to tackle increasing quality demands and costs pressures. Resulting from that, a variety of tolerancing activities exist, which are closely interconnected with the product development process. Their application leads to several artifacts, which can be gathered in a digital thread weaving through the processes. As most of these approaches are document-centered, new progresses in model-based systems engineering offer unused potential to ensure traceable processes. This chapter therefore presents an approach for the model-based formalization of tolerancing activities to contribute to this digital thread. Furthermore, a holistic approach for a common key characteristic model is described, which is used along with the formalized activities. Due to their importance for tolerancing, key characteristics are a profound basis for enabling traceability and the approach ensures a thorough link. It includes the systematic and automated derivation of key characteristics from requirements using natural language processing, their further extension and prioritization.<br

Interdisziplinäres prozessorientiertes Toleranzmanagement – ein Konzept - Heling, Björn; Schleich, Benjamin; Wartzack, Sandro (Summer School Toleranzmanagement Beiträge zur 3. Summer School, 2017)
Keywords: Toleranzmanagement; interdisziplinäres Toleranzmanagement

Introducing Emotional Bionics to Support Subjective Value Creation in Technical Products - Zöller, Susan; Schröppel, Tina; Wartzack, Sandro (International Journal of Affective Engineering, 2019)
So far, bionic design has mainly been applied to support functional solutions. In recent times, subjective aspects in product quality become increasingly important to users, too. Under the aspect of targeting a sustainable value creation for users, bionic design may also help to better address users’ subjective needs in product design. Therefore, a new methodology is presented. Its first step is the numeric and perception-related investigation of main geometrical criteria in object shape changes between technical solutions and their bionic models. The second step is the identification and utilization of impressions analogies between the two domains. Thus subjective similarities between the product and its bionic model are examined both in geometrical and in impressions respect in order to derive implications for the field of Emotional Bionics. The methodology is explained in detail by applying a pilot stud
Keywords: Emotional bionics; Subjective value creation; Design analytics

Introduction of a computational approach for the design of composite structures at the early embodiment design stage - Klein, Daniel; Malezki, Waldemar; Wartzack, Sandro (Proceedings of the 20th International Conference on Engineering Design (ICED15), Vol. 4: Design for X, 27.-30. Juli 2015, Mailand, 2015, S. 11-20., 2015)
UnivIS-Import:2015-10-26:Pub.2015.tech.FT.FT-KLMEFK.introd

Intuitive virtual reality - CAD assembly system - Fechter, Marius; Miehling, Jörg; Stangl, Thomas; Wartzack, Sandro (Proceedings of the DESIGN 2014 13th International Design Conference, 2014)
The application of virtual reality during the design engineering process possesses the potential to experience and to interact with virtual products in a natural and intuitive manner. Some workflows in the field of computer-aided design, like assembling components, exhibit disadvantages that result from the two-dimensional vision and the limitations of common human-computer interaction. To support the design engineer, this paper focuses on developing a framework that harnesses the benefits of intuitive gesture based hand interaction and stereoscopic visualisation.
UnivIS-Import:2015-04-16:Pub.2014.tech.FT.FT-KLMEFK.intuit
Keywords: virtual reality; computer-aided design; gesture interaction

Intuitive, VR- and Gesture-based Physical Interaction with Virtual Commissioning Simulation Models - Metzner, Maximilian; Krieg, Lorenz; Krüger, Daniel; Ködel, Tobias; Franke, Jörg (Annals of Scientific Society for Assembly, Handling and Industrial Robotics, 2020)
To manage complexity in modern, highly automated production systems, functional simulation for logic validation, known as virtual commissioning, is an important enabler. However, established systems for virtual commissioning are highly specialized software, which are solely used by simulation experts. In this contribution, we present a system for intuitive, user-integrated virtual commissioning. Using virtual reality, we allow for a first person experience of the simulation at runtime. By implementing a stereo-camera-based hand tracking system, we facilitate intuitive manual interaction with the simulation, including physical manipulation. Furthermore, we also integrate common human-machine interfaces, like touch panels, which are directly streamed from the industrial controller, offering the operator comparable interaction experience as with the real system. We conduct a user study quantifying the intuitiveness of interaction for defined tasks of our system compared to a standard simulation setup.<br
Keywords: Virtual Commissioning; Virtual Reality; Motion Capturing

Inversdynamische Berechnungen der Muskelkräfte am Glenohumeralgelenk unter der Prämisse der Biegeminimierung - Uttich, Eike; Gößling, Rainer; Bartz, Marcel; Bender, Beate (Conference Proceedings: 35. CADFEM ANSYS Simulation Conference, 2017)

Investigating Modeling in Early Robust Design – A Study with the Modeling Method of Embodiment Function Relation and Tolerance Model - Li, Jiahang; Horber, Dennis; Renner, Philip; Jiajie, Yan; Götz, Stefan; Grauberger, Patric; Wartzack, Sandro; Matthiesen, Sven (Proceedings of NordDesign 2024, 2024)
Robust design (RD) aims to design systems that are insensitive to variation, reducing costly iterations in later product development stages. Evaluation of the early RD methods, often case-based like the modeling method with the EFRT model, lacks empirical investigation with novice applicants, which hinders further research into the success criteria of these methods. In this paper, a cross-over study evaluating the applicability and efficacy of the modeling method revealed its support for early RD. This encourages further RD research and provides a foundation for future investigatio
Keywords: Empirical Studies; Robust Design; Design Methods; Design Models

Investigation of Failure Mechanisms in Oil-Lubricated Rolling Bearings under Small Oscillating Movements: Experimental Results, Analysis and Comparison with Theoretical Models - Halmos, Fabian; Wartzack, Sandro; Bartz, Marcel (Lubricants, 2024)
Bearing life calculation is a well-researched and standardized topic for rotating operation conditions. However, there is still no validated and standardized calculation for oscillating operation, only different calculation approaches. Due to the increasing number of oscillating rolling bearings, for example, in wind turbines, industrial robots, or 3D printers, it is becoming more and more important to validate one of these approaches or to formulate a new one. In order to achieve this goal, the damage mechanisms for oscillating operating conditions must first be analyzed in more detail by means of experimental investigations. The open question is whether fatigue is the relevant damage mechanism or whether wear damage, such as fretting corrosion or false brinelling, dominates. The present work therefore shows under which oscillation angle and frequency fatigue occur in oil-lubricated cylindrical roller bearings.<br
Keywords: bearings; oscillation; oscillating movements; wear; fatigue; rating life

Investigation of surface skeletonization methods for reconstruction of topology optimized structures - Mayer, Johannes; Wartzack, Sandro (Proceedings of the 31st Symposium Design for X, DFX 2020, 2020)
By showing where to place material in a specified design space, the continuous topology optimization is very useful in product development of structural loaded components. However the optimizations design proposal is far from being a parametric CAD-model. Instead it usually consists of a tesselated surface, that has to be re-engineered. As this is often done manually, it takes a lot of time and expert knowledge. Curve skeleton algorithms have proven their ability to support the restructuring of truss-like design proposals by providing references for construction elements. To investigate a similar design concept for general optimization results, showing truss-like structures as well as surface-like sections, the suitability of surface skeletons for topology reconstruction is examined.
CRIS-Team Scopus Importer:2021-04-19
Keywords: Computational Geometry; Medial Axis Transform; Surface Skeleton; Topology Optimization

Investigation of the tribological behavior of amorphous carbon coatings for total knee replacement using a pin-on-disk tribometer - Rothammer, Benedict; Neusser, Kevin; Marian, Max; Bartz, Marcel; Wartzack, Sandro (7th World Tribology Congress, WTC 2022, 2022)
Great efforts are made to reduce the aseptic loosening of total knee replacements, for example by biotribologically effective surface modifications in order to decrease the wear of polymer inlays. This study focused on the characterization and tribological testing of wear-reducing amorphous carbon coatings with good adhesion to the medical technology materials Co28Cr6Mo and PE-UHMW. Thereby, the present study showed the applicability of coatings to the considered materials and the high potential for wear reductio
Keywords: Total knee replacement; Biotribology; PVD Coatings; Wear

Investigation of the tribological performance of a-C:H coating systems by modifying adhesive layer for application in dry deep drawing - Rothammer, Benedict; Zhao, Rong; Krachenfels, Kim; Merklein, Marion; Tremmel, Stephan (International Tribology Conference Sendai 2019, 2019)
Lubricants are essential in conventional deep drawing processes to improve the tribological behavior and product quality. Requirements for increasing sustainability and resource efficiency motivate the realization of lubricant-free deep drawing processes. However, the direct contact between tool and workpiece during dry deep drawing leads to increased adhesive wear and surface damage on the sheet metal. A promising approach to face these challenges due to dry deep drawing is the application of amorphous carbon coating systems on tool surfaces. The roughness peaks on the coating surface caused by deposition have to be kept as low as possible, in order to reduce the risk of abrasive wear caused by interlocking into the ductile metal sheet and thus the initial adhesive wear can be avoided. In this study, the influence of adhesive layer on the topography of a‑C:H functional layer is investigated and its tribological performance verified. The modified deposited a‑C:H coating system exhibits similar adhesion to the substrate as the standard a‑C:H coating system. In addition, it shows a more homogeneous surface topography without formation of droplets. Due to the modified adhesion layer, the Rpk value in as-deposited state is 10 times lower by changing the deposition technique of the chromium adhesive layer. As a result, the extremely low roughness peaks of the coating penetrate only slightly into the rough sheet surface with EDT texturing. The standard and modified a‑C:H coated tool surfaces against two common used aluminum alloys (AA6014, AA5182) are applied for the tribological evaluation by the flat strip drawing test. The analysis of the resulting coefficients of friction shows that the tribological behavior is directly influenced by the roughness. The roughness of the functional layer and thus the tribological behavior can be changed by the application of different adhesive layers. Furthermore, the tool and workpiece surfaces are characterized before and after the test in order to investigate wear mechanisms on tool
Keywords: Tribology; Dry Sheet Metal Forming; Diamond-like Carbon (DLC) Coating; Roughness

Investigation of Tribological Behavior of Carbon Coatings in Dry Sheet Metal Forming - Steiner, Jennifer; Zhao, Rong; Tremmel, Stephan; Merklein, Marion (Proceedings 12th International Conference THE "A" Coatings 2016, 2016)
Keywords: Dry Sheet Metal Forming; Carbon Coating; Tribology; Friction

Investigation of Tribological Behaviour of a-C:H Coatings for Dry Deep Drawing of Aluminium Alloys - Zhao, Rong; Steiner, Jennifer; Andreas, Kolja; Merklein, Marion; Tremmel, Stephan (Abstracts Programme, 2016)
Keywords: Dry metal forming; DLC; aluminium; adhesive wear

Investigation of tribological behaviour of a-C:H coatings for dry deep drawing of aluminium alloys - Zhao, Rong; Steiner, Jennifer; Andreas, Kolja; Merklein, Marion; Tremmel, Stephan (Tribology International, 2017)
Lubricant‑free sheet metal forming increases resource efficiency and contributes to environmental protection. One approach to reducing friction and wear in dry forming is the tool-sided application of carbon-based coatings. In this work, amorphous hydrogenated carbon (a‑C:H) coatings were prepared by plasma‑enhanced chemical vapour deposition (PECVD). The coating samples were deposited under different amounts and ratios of acetylene (C2H2) and argon (Ar) gas atmospheres. The coating samples were characterized regarding their thickness, roughness and mechanical as well as chemical bond structures. The tribological behaviour against aluminium alloys was investigated under lubricant‑free conditions with a ring‑on‑disc tribometer. The relationships between chemical bond composition and coating properties were clarified. Finally, one a-C:H coating variant with promising tribological performance against aluminium alloys was exemplarily tested in a flat strip drawing test, which models the tribological conditions in the flange area of a deep drawing process.
Keywords: Dry sheet metal forming; DLC; aluminium; adhesive wear

Investigation of Tribological Systems for Dry Deep Drawing by Tailored Surfaces - Merklein, Marion; Schmidt, Michael; Tremmel, Stephan; Wartzack, Sandro; Andreas, Kolja; Häfner, Tom; Zhao, Rong; Steiner, Jennifer (Dry Metal Forming Open Access Journal, 2015)

Investigation on the tribological-mechanical behavior of amorphous carbon coatings by load-scanning tests - Hetzner, Harald; Schaufler, Jens; Pejic, Goran; Tremmel, Stephan; Durst, Karsten; Wartzack, Sandro (Materialwissenschaft und Werkstofftechnik, 2012)
Amorphous carbon coatings have a beneficial tribological behaviour since they provide low friction even under dry sliding conditions and at the same time they offer a good wear protection. Under high loads, the applicability of state-of-the-art amorphous carbon coatings is limited by mechanical failure. However, there is still little knowledge concerning the precise failure mechanisms under application-oriented conditions. In the present study, cylindrical specimens of a cold work tool steel were coated with two commercial amorphous carbon coating systems: a WCC coating with an a-C:H:W top layer and a DLC coating which architecture is based on that of the WCC coating, but contains an additional a-C:H top layer. The coated specimens were tested on a load-scanning test rig in dry sliding contact against uncoated specimens of the same steel substrate. In the tests, the specimens were loaded with a normal force in the range of 13 and 350 N, corresponding to a maximum contact pressure of 1 to 3 GPa. The number of load cycles was varied between 1 and 60. Firstly, the load-dependent friction behaviour was monitored. Secondly, the tests were stopped at different total cycle numbers allowing for an evaluation of the progress of wear and damage by scanning electron microscopy. For both coating systems, adhesive pick-up of counter body steel was observed prior to mechanical failure. Whilst the WCC coating system showed first indications of local failure after several load cycles and at contact pressures exceeding 2 GPa, the DLC coating system showed catastrophic failure on a global scale only after few load cycles and over the whole investigated load range.
EAM Import::2019-03-13

Investigations on cage dynamics in rolling bearings by test and simulation - Schwarz, Sebastian; Grillenberger, Hannes; Tremmel, Stephan (74th STLE Annual Meeting & Exhibition, 2019)
Rolling bearing cages perform a very high-frequency movement within their cage pocket clearance compared to the rotational speed under certain operating conditions. This is often accompanied by higher elastic deformation and noise. An unstable cage movement causes high contact forces and reduces the performance of the bearing used. The presentation gives an overview of the essential properties of the unstable cage movement derived by multi-body simulations. Relations between the cage movement and the boundary conditions in the simulation such as coefficient of friction and load are identified. Based on the simulation results, an index is defined that allows the calculated or measured cage movement to be classified into different types and objectively evaluates the cage dynamics. A comparison of the calculated and experimentally measured cage dynamics for different load cases is presented to validate the simulation results.<br

Investigations on the rolling bearing cage dynamics with regard to different operating conditions and cage properties - Schwarz, Sebastian; Grillenberger, Hannes; Tremmel, Stephan; Wartzack, Sandro (IOP Conference Series: Materials Science and Engineering, 2021)
The dynamic behavior of a cage can have a significant influence on the performance and the noise of a rolling bearing. In case of an unstable or high-frequency cage movement, vibrations are transmitted to the adjacent machine elements and the environment, which can influence the operating behavior of the whole system. In addition, a loud noise can often be perceived, which is referred to in the literature as cage rattling or squealing. In this paper, characteristics of different cage movements are investigated using multibody simulations and experimental investigations. For this purpose, essential properties of the fundamentally observable cage movement types "stable", "unstable" and "circling" are presented. The calculated cage dynamics and the type of cage motion are used to show dependencies between the operating conditions and the resulting cage movement such as inner ring rotational speed, bearing load or cage characteristics such as pocket clearance. Based on the simulations, interactions between the input parameters can also be determined. The results are used to identify operation-critical conditions and cage properties that lead to high cage dynamics. Finally, a comparison between the results of the multibody calculations and optical measurements is made. The optical measurements are performed using high-speed cameras. Reference markers fixed on the cage and digital image correlation allow the evaluation of the kinematics as well as the deformation of the cage. These results are compared with the simulation data to ensure a high quality of dynamics simulatio
Keywords: Rolling Bearing; Rolling Bearing Cage Dynamics; Dynamics

Irradiation-dependent topology optimization of metallization grid patterns and variation of contact layer thickness used for latitude-based yield gain of thin-film solar modules - Zinßer, Mario; Braun, Benedikt; Helder, Tim; Magorian Friedlmeier, Theresa; Pieters, Bart; Heinlein, Alexander; Denk, Martin; Göddeke, Dominik; Powalla, Michael (MRS Advances, 2022)
Abstract: We show that the concept of topology optimization for metallization grid patterns of thin-film solar devices can be applied to monolithically integrated solar cells. Different irradiation intensities favor different topological grid designs as well as a different thickness of the transparent conductive oxide (TCO) layer. For standard laboratory efficiency determination, an irradiation power of 1000W/m2 is generally applied. However, this power rarely occurs for real-world solar modules operating at mid-latitude locations. Therefore, contact layer thicknesses and also lateral grid patterns should be optimized for lower irradiation intensities. This results in material production savings for the grid and TCO layer of up to 50 % and simultaneously a significant gain in yield of over 1% for regions with a low annual mean irradiation. Graphical Abstract: [Figure not available: see fulltext.]
CRIS-Team Scopus Importer:2022-08-12

Isolating the effect of residual stresses on coating wear by a mechanical stress relaxation technique - Vierneusel, Bernd; Benker, Lisa; Tremmel, Stephan; Göken, Mathias; Merle, Benoit (Thin Solid Films, 2017)
Residual stresses play an essential role for the tribological performance of sputtered coatings since compressive residual stresses yield positive effects on wear resistance. As deposition induced residual stresses are always related to the coating microstructure, a combination of different effects is typically assessed if coatings are validated by tribological testing. Therefore, the real effect of residual stresses on the tribological performance of coatings is not entirely clear. The study aims to examine this issue by isolating the residual stress effect from the microstructural impact by mechanical relaxation of the coating after the deposition process. For this purpose, MoS2 coated substrates are mechanically pre-stretched during the coating process and relaxed again afterwards in order to reduce the coating's macroscopic residual stresses. Other samples, which are not pre-stretched but coated inside the same process with identical distance to the target, serve as a reference material. The proper function of the relaxation technique is demonstrated by applying a recently developed method for residual stress measurement, namely the “Focused Ion Beam – Digital Image Correlation” method. Both samples, the relaxed and as-deposited one, were subjected to a tribological pin-on-disk test. The results show that at high compressive residual stress levels, only mild wear at the upper surface inside the contact area occurs. In contrast, at low compressive residual stress levels, wear results from an abrasive material removal inside the contact track but most significantly from additional coating detachments outside the contact area. The observations can be related, firstly, to a superimposition of harmful bending stresses and beneficial compressive residual stresses beneath the contact area and, secondly, to a stress relaxation effect taking place only inside the tribological contact zone. In summary, owing to the developed stress relaxation technique, a microstructurally independent effect of residual stresses on wear resistance of sputtered MoS2-coatings has been prove
Keywords: Residual stress; Wear; MoS2; Sputtering; Relaxation

Kennzahl zur Identifikation der Wälzlagerkäfigdynamik - Schwarz, Sebastian; Grillenberger, Hannes; Tremmel, Stephan (VDI-Berichte 2348, 2019)
Moderne Wälzlagerungen müssen heute nicht mehr nur hohen Ansprüchen an Lebensdauer und Führungsgenauigkeit genügen, sondern es werden auch minimale Reibungsverluste und Störgeräusche gefordert. Störgeräusche entstehen insbesondere dann, wenn unter bestimm-ten Betriebsbedingungen der Käfig eines Wälzlagers zusätzlich zu seiner Rotation eine über-lagerte, im Vergleich zu seiner Drehzahl sehr hochfrequente Bewegung durchführt, die als Geräuschquelle fungiert und häufig von einer starken Käfigverformung begleitet ist. Dieses Phänomen wird in der Literatur als „Käfiginstabilität“ oder „Käfigrasseln“ bezeichnet. In diesem Beitrag wird anhand zahlreicher Mehrkörpersimulationen die Käfigbewegung in ver-schiedenen Wälzlagern unter unterschiedlichen Betriebsbedingungen systematisch analysiert. Hieraus lassen sich grundsätzliche, verallgemeinerbare Bewegungstypen ableiten. Darauf aufbauend wird eine Methodik präsentiert, die es erlaubt, die in einer Simulation berechnete beziehungsweise in einem Experiment gemessene Käfigbewegung automatisiert und mit ho-her Zuverlässigkeit den zuvor definierten Bewegungstypen zuzuordnen. Diese Methodik er-laubt somit eine objektive Beurteilung der Käfigdynamik.<br
CRIS-Team Scopus Importer:2024-12-16
Keywords: Wälzlager; Dynamiksimulation; Wälzlagerkäfig; Diskriminanzanalyse

KI, digitaler Zwilling und die Zukunft der Produktentwicklung - Wartzack, Sandro (Konstruktion, 2024)
CRIS-Team Scopus Importer:2024-11-22

KI-gestützte Anforderungsformalisierung und Architekturmodellerstellung für das MBSE - Schleifer, Simon; Lungu, Adriana; Kruse, Benjamin; van Putten, Sebastiaan; Götz, Stefan; Wartzack, Sandro (WiGeP News, 2024)

KI in der Entwicklung – Eine Revolution für die Konstruktion - Wartzack, Sandro (Konstruktion, 2023)
CRIS-Team Scopus Importer:2023-08-04

Klassifikation und Handhabung von Unsicherheiten zur entwicklungsbegleitenden Erfassung des Produktreifegrades - Luft, Thomas; Wartzack, Sandro (Entwerfen Entwickeln Erleben 2014 – Beiträge zur virtuellen Produktentwicklung und Konstruktionstechnik, 2014)
1. Motivation und Zielsetzung Das heutige Unternehmensumfeld ist besonders gekennzeichnet durch eine hohe Komplexität und Dynamik, bedingt durch den zunehmenden technologischen Fortschritt, die gestiegenen und individuelleren Kundenanforderungen sowie die Vielzahl interner und externer Einflussfaktoren. Um trotz dieser Aspekte Wettbewerbsfähigkeit  zu gewährleisten, ist die rasche und gleichzeitig zuverlässige Entwicklung marktfähiger Produkte von herausragender Bedeutung. Um einen erfolgreichen Verlauf eines Entwicklungsprojektes sicher zu stellen, kommt neben der kontinuierlichen Verfolgung von vergangener Zeit und entstandenen Kosten auch der Produktreife eine Schlüsselrolle zu. Sie stellt die Ermittlung und den Abgleich der aktuellen mit der ursprünglich geplanten Produktreife zu einem bestimmten Zeitpunkt dar und dient als Grundlage für die Ergreifung entsprechender Maßnahmen zur Einhaltung der Ziele. Vor diesem Hintergrund und der Zielvorgabe, Produkte schnell, kostengünstig und ausgereift auf den Markt zu bringen, sieht sich die moderne Produktentwicklung mit einer Reihe von Unsicherheiten konfrontiert, die nicht nur das Entwicklungsprojekt an sich erschweren, sondern sich auch auf die Reifegradermittlung eines Produktes auswirken. Die Ermittlung der Produktreife erfordert die Verwendung von Informationen, deren Inhalt vor allem zu Beginn der Entwicklungstätigkeiten größtenteils auf Annahmen beruht und daher in hohem Maße unsicher ist. Der Grad an Unsicherheit wird noch verstärkt durch die Möglichkeit, dass bestimmte Daten und Fakten möglicherweise vollkommen unbekannt sind bzw. vernachlässigt werden. Wird diese Vielzahl an Unsicherheiten nicht rechtzeitig bei der Entwicklung eines Produktes berücksichtigt, hat dies unter Umständen weitreichende Konsequenzen für das Entwicklungsprojekt und das betroffene Unternehmen, da besonders die Entscheidungen in den frühen Phasen der Entwicklung einen großen Einfluss auf Kosten, Qualität und Produktfunktionalität haben. Die Zielsetzung des Beitrages ist daher zum einen die Erarbeitung eines Ansatzes zur Ermittlung und Handhabung von Unsicherheiten, die während des Entwicklungsprozesses auftreten können. Zum anderen ist es das Ziel, die klassifizierten Unsicherheiten bei der Reifegradbestimmung eines Produktes zu berücksichtigen und sie derartig (mathematisch) zu integrieren, dass trotz vorliegender Unsicherheiten eine möglichst zuverlässige Aussage zum Produktreifegrad getroffen werden kann.   2. Stand der Technik und Wissenschaft Im Grundlagenteil werden zunächst die für diesen Beitrag relevanten Methoden und Ansätze in der Produktentwicklung dargelegt. So werden die beiden Ansätze „Simultaneous Engineering“ und „Design for X“ vorgestellt, um schließlich auf das Konzept der integrierten Produktentwicklung einzugehen. Die Grundidee der integrierten Produktentwicklung ist eine gleichzeitige, eng miteinander verknüpfte Entwicklung des Produktes und der mit diesem in Verbindung stehenden Prozesse. Darüber hinaus werden unter Betrachtung des gesamten Produktlebenszyklus bereits frühzeitig alle relevanten internen und externen Einflüsse und Rahmenbedingungen in der Entwicklungsphase berücksichtigt. Anschließend wird neben der Definition des Begriffes „Unsicherheit“ und der Abgrenzung zu verwandten Begriffen wie „Risiko“ und „Ungewissheit“ erläutert, weshalb die Analyse von Unsicherheiten während des Produktentwicklungsprozesses eine hohe Relevanz besitzt und welchen Einfluss der Neuheitsgrad eines Produktes auf das Ausmaß der Unsicherheiten hat. Abschließend werden die in der Literatur für die Bestimmung des Entwicklungsfortschrittes existierenden Ansätze ausführlich betrachtet und deren Schwächen (z.B. keine Berücksichtigung von Unsicherheiten in der Berechnung des Produktreifegrades) aufgezeigt.   3. Betrachtung von Unsicherheiten in der Produktentwicklung Im Rahmen des Beitrages erfolgt eine Unterscheidung zwischen internen und externen Unsicherheiten, da zwischen beiden Typen ein großer Unterschied im Hinblick auf die Beeinflussbarkeit der auftretenden Unsicherheiten durch Unternehmen existiert. Anschließend erfolgen die Klassifizierung der Unsicherheiten bezüglich ihrer Quelle (z.B. produktinhärente Unsicherheiten, Unsicherheiten aus dem Produktlebenszyklus) und Art (z.B. Ungenauigkeit, Unzuverlässigkeit) sowie die Eingrenzung der Unsicherheiten hinsichtlich ihres zeitlichen Auftretens während des Entwicklungsprozesses. Darauf aufbauend wird eine Vorgehensweise entwickelt, die potenzielle Unsicherheiten in einem Entwicklungsprojekt identifiziert und priorisiert. Über die Bestimmung der Unsicherheitsgrade der als relevant eingestuften Unsicherheiten wird schließlich eine Matrix aufgestellt, mit deren Hilfe ein Überblick über die Unsicherheiten eines Entwicklungsprojektes gewonnen und das projektspezifische Unsicherheitsprofil gebildet werden kann. Dazu werden spezifische Unsicherheitsfunktionen verwendet, die eine grafische Abbildung des Zusammenhangs zwischen dem Kriterium einer Unsicherheitsart und dem Unsicherheitsgrad ermöglichen. Die sich daran anschließende Ableitung von Normstrategien für die Handhabung von Unsicherheiten dient der Behebung bzw. Minimierung der ermittelten Unsicherheiten und der mit ihnen verbundenen Risiken im Entwicklungsprozess.   4. Integration von Unsicherheiten in die Produktreifegradermittlung Nach der Betrachtung von Unsicherheiten in der Produktentwicklung wird zunächst das erstellte Modell zur Reifegradermittlung vorgestellt, um anschließend die Vorgehensweise zur Integration von Unsicherheiten in dieses Modell darzustellen. Da vorhandene Reifegradmodelle aus der Literatur nur unzureichend für die spätere Integration der Ergebnisse aus der Unsicherheitsanalyse geeignet sind, wird das neu entwickelte Modell zur Bestimmung des Produktreifegrades, das die vorhandenen Ansätze als Basis nutzt und diese kombiniert, ausführlich erläutert. Prinzipiell dient hierbei der nach VDI 2221 definierte Konstruktionsprozess als Grundlage zur Ermittlung des Produktreifegrades. Um diesen abzuschätzen bzw. zu bewerten, müssen die zum Ermittlungszeitpunkt tatsächlich erfüllten Ist-Vorgaben an das Produkt mit den festgelegten Sollvorgaben verglichen werden. Neben der Erläuterung des Aufbaus und der einzelnen Bestandteile des Reifegradmodells wird zusätzlich eine beispielhafte Berechnung des Gesamtreifegrades eines Produktes, der sich aus dem Planungs- und Konzeptionsreifegrad, dem Konstruktionsreifegrad und dem Dokumentationsreifegrad zusammensetzt, durchgeführt. Auf Basis dieses Modells wird schließlich ein Schema entwickelt, das die zuvor ermittelten Unsicherheiten in das Reifegradmodell integriert. Hierfür sind zunächst die entsprechenden Faktoren im Modell zu identifizieren, die durch die Unsicherheiten potenziell beeinflusst werden. Über die Einführung verschiedener Unsicherheitsvariablen werden schließlich die Unsicherheitsgrade der verschiedenen Unsicherheiten aggregiert und dadurch der Ist-Wert des Reifegrades verringert. Anschließend wird darauf eingegangen, dass der berechnete Reifegrad unter Unsicherheit als Minimum anzusehen ist. Dieses Ergebnis dient als Ausgangsbasis zur Berechnung des Erwartungswertes des Reifegrades unter Zuhilfenahme von Erkenntnissen aus der Wahrscheinlichkeitstheorie. Zur besseren Nachvollziehbarkeit wird der vorgestellte Ansatz durch Integration von Unsicherheiten in das zuvor verwendete Beispiel zur Reifegradermittlung nochmals nachgerechnet und dadurch anschaulich dargestellt.   5. Zusammenfassung und Nutzen Mit den beiden vorliegenden Ansätzen zur Klassifizierung von Unsicherheiten und zur Integration von Unsicherheiten in den Prozess der Reifegradermittlung wurde eine Basis geschaffen, die dazu beiträgt, die eingangs erwähnten Probleme und Schwierigkeiten in der heutigen Produktentwicklung greifbarer zu machen und letztendlich auch zu reduzieren. Neben der Sicherstellung einer entsprechenden Produktreife bei Entwicklungsende können durch die kontinuierliche Ermittlung des Reifegrades unter Berücksichtigung der Unsicherheiten frühzeitig Verzögerungen und Abweichungen im Projektverlauf identifiziert werden und entsprechende Maßnahmen zur Gegensteuerung ergriffen werden. Somit rechtfertigt sich auch der durch Realisation des Ansatzes entstehende Mehraufwand zur Erfassung und Auswertung bestimmter Informationen. Durch eine reifegradgesteuerte Produktentwicklung wird nicht nur ein stetiger Anstieg des Entwicklungsfortschritts gewährleistet, sondern auch die Gefahr von zeit- und kostenintensiven Iterationen im Konstruktionsprozess verringert. Der Produktreifegrad ist somit ein essenzieller Bestandteil einer Projektüberwachung im Bereich der Produktentwicklung.
Keywords: Produktreifegradmanagement; Unsicherheiten; Entwicklungscontrolling; Entscheidungsfindung

Knowledge and Data-Based Design and Dimensioning of Mechanical Joining Connections - Zirngibl, Christoph; Sauer, Christopher; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the ASME 2022 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, 2022)

Knowledge-based and calculation-supported concept validation in the early stages of product development using the example of the electric motor - Tüchsen, Johann; Richter, Michael; Heydenreich, Johannes; Koch, Matthias; Schleich, Benjamin; Wartzack, Sandro (NAFEMS 18 DACH Conference, 2018)
In order to prevent costs and unneeded effort in product development, design verifications in early development phases are used to identify non-suitable designs and errors. Therefore, this contribution proposes a concept for a completely automated design check based on simplified one-dimensional calculations including knowledge-based correction factors optimized for electric drives. Using knowledge-based systems (KBS) structure in combination with compiled template computer scripts, a very fast and multidisciplinary solution is given to evaluate the suitability of the created solution regarding the requirements. Furthermore, this concept is expandable for additional modules or motors and easy to maintain. <br
Keywords: Concept validation; knowledge-based systems; KBS; analytical models

Knowledge-based design of surface textures for TEHL contacts - Marian, Max; Tremmel, Stephan; Wartzack, Sandro (3rd Young Tribological Researcher Symposium, 2019)
Dwindling resources and stricter legal requirements call for efficient machine elements and engine components. Therefore, tribological contacts with low frictional losses are vital. This can be achieved, for example, by applying discrete micro-textures to the surfaces of contacting bodies in lubricated tribological systems. While this approach has already been intensively investigated for lower loaded conformal contacts under hydrodynamic lubrication, the application and design of surface textures for higher loaded, non-conformal contacts under thermo-elastohydrodynamic lubrication (TEHL) is much more controversially discussed and still under basic research. In this context, tribo-simulations offer the great potential to explore the underlying basic mechanisms in terms of friction and wear reduction and to facilitate design optimization in order to avoid time-consuming and costly trial-and-error experiments. The aim of this contribution was therefore to investigate the impact of different micro-texture’s characteristics on the tribological behavior using transient 3D TEHL simulations based upon a full-system approach. Meta-models of optimal prognosis (MOP) and evolutionary algorithms (EA) were utilized to predict optimized and robust texture designs with reasonable computational effor
Keywords: Micro-texturing; Elastohydrodynamic lubrication; Optimization; Texture design

Knowledge-based product and process design synthesis of additively manufactured non-assembly mechanisms - Schächtl, Paul; Götz, Stefan; Schleich, Benjamin; Wartzack, Sandro (Journal of Engineering Design, 2024)
Additive Manufacturing increasingly becomes a viable alternative to conventional manufacturing technologies. However, the knowledge and awareness to achieve a ready-for-manufacturing and quality-ensured design of additively manufactured products are mostly lacking. Knowledge from the manufacturing process on how certain process variables affect the product requirements must already be considered in product design to assure and potentially enhance the quality a priori, thus saving time and cost-intensive iterations. Therefore, this knowledge must be front-loaded as a basis to suitably adapt product and process design simultaneously. This contribution therefore proposes a framework for the simultaneous product and process design synthesis of existing designs by providing insight knowledge about product and process design specific to Fused Layer Modeling. This is achieved via a consolidated ontology-based knowledge representation and its integration in a design environment. Thus, the aim, in contrast to most existing approaches, is to provide this knowledge on a product- and application-specific basis to parallelise product and process design for non-assembly mechanisms and exploit currently unused potential concerning the interaction between the different domains. This can shorten development times and also compensate for a lack of background knowledge in certain areas. A practical use case highlights the general procedure, benefits, and applicability.
CRIS-Team Scopus Importer:2024-05-10
Keywords: Additive manufacturing; fused layer modeling; knowledge-based engineering; ontology; process design; product design

Knowledge-driven Design for Additive Manufacturing: A Framework for Design Adaptation - Schächtl, Paul; Götz, Stefan; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the Design Society, 2023)
Due to the high freedom of design, additive manufacturing (AM) is increasingly substituting conventional manufacturing technology in several sectors. However, the knowledge and the awareness for the suitable design of additively manufactured components or assemblies ensuring manufacturability and fully realizing its potential is still lacking. In recent years, approaches and tools have emerged that allow the incorporation of existing knowledge of Design for Additive Manufacturing (DfAM) into the design process. Nevertheless, these applications mostly do not consider the formalisation of both restrictive and opportunistic DfAM guidelines for their integration in design tools. Therefore, the following article presents a framework for the knowledge-driven adaptation of existing designs in the context of DfAM within an expert system. The novelty of the presented approach lies in the interdisciplinarity between the formalization of design guidelines and their integration and consideration within computeraided design for the semi-automated adaptation of functional non-assembly mechanisms. The application of the presented framework to a case study manufactured via Fused Layer Modeling (FLM) illustrates the applicability and benefits.<br
Keywords: Additive Manufacturing; Knowledge-driven Design; Design for Additive Manufacturing (DfAM); Ontologies

Komplexitätsreduzierte integrative Struktursimulation kurzfaserverstärkter Kunststoffbauteile mit LS-Dyna - Gruber, Georg; Liebst, Fabian; Wartzack, Sandro (ANSYS Conference & 32th CADFEM Users' Meeting., 2014)
UnivIS-Import:2015-04-16:Pub.2014.tech.FT.FT-KLMEFK.komple

Konzept einer CAE-Methode zur systematischen Auslegung beanspruchungsgerechter, kurzfaserverstärkter AM-Fachwerksknoten für hochoptimierte Fachwerke - Jäger, Michael; Völkl, Harald; Wartzack, Sandro (Proceedings of the 31st Symposium Design for X (DFX2020), 2020)
Trusses represent an economical, rigid and effective lightweight construction method. However, the connecting parts (nodes) between the struts are a design challenge, especially in highly optimized trusses. Several struts with different geometries (diameter, cross-sections) must be connected at any spatial angle in one point in a manner that is suitable for the load. The use of fibre-reinforced materials for the struts is common practice, for the nodes, metals are usually used. However, these do not exploit the full lightweight construction potential of the truss. The proposed method allows the design of truss nodes using fibre-reinforced materials and additive manufacturing, while taking into account the geometric boundary conditions of the connection points for the strut
Keywords: Structural optimization; CFRP truss; lightweight design; short fibre reinforced plastics

Konzept eines erweiterten Produktbeschreibungsansatzes basierend auf dem Vergleich des Characteristics-Properties-Modelling und der matrixbasierten Produktbeschreibung - Crostack, Alexander; Luft, Thomas; Binz, Hansgeorg; Wartzack, Sandro; Roth, Daniel (Stuttgarter Symposium für Produktentwicklung (SSP), 2015)
Die Produktentwicklung ist geprägt von steigenden Anforderungen an Qualität, Kosten und Funktionalitäten technischer Produkte. Zur Unterstützung der Produktentwickler wurden verschiedene Ansätze zur Modellierung von Produkten und Prozessen entwickelt. Im Rahmen des Beitrags werden die beiden Ansätze, das Characteristic-Properties-Modelling (CPM) und die matrixbasierte Produktbeschreibung (MBPB), analysiert. Die Vorteile des CPM liegen in der Genauigkeit der Modellierung und die Vorteile der MBPB in der Unterstützung der Produktentwickler. Darauf aufbauend wird das Konzept eines weiterentwickelten Ansatzes, der er-weiterten matrixbasierten Produktbeschreibung (eMBPB), entwickelt. Die eMBPB kombiniert die MBPB von Produkten mit der grafischen Darstellung und der Genauigkeit des CPM. Zur Veranschaulichung werden beide Ansätze exemplarisch anhand eines vereinfachten Modells eines Fahrradrahmens angewendet. Der Beitrag endet mit einer kritischen Diskussion und zeigt weiteres Forschungspotenzial auf.
Keywords: Characteristics-Properties Modelling (CPM); Matrixbasierte Produktbeschreibung (MBPB); Konstruktionsmethodik; Produktmodellierung

Konzept für den MBSE-Einsatz zur automatisierten Individualisierung von komplexen Produkten - Dworschak, Fabian; Zirngibl, Christoph; Schleich, Benjamin; Wartzack, Sandro (Beiträge zum 30. DfX-Symposium, 2019)
Due to increasing market transparency, companies are mainly focusing on development of customized products. In this course, a competitive advantage should be achieved through the automated adaptation of product characteristics. In order to achieve this, development engineers focus primarily on modifying existing designs and refrain from re-running the entire product development process (PDP). However, this approach is primarily limited to the CAD environment. Previous phases of the PDP are not integrated, leading to a lack of traceability and continuity. Media breaks and API conflicts arise which increase costs. In order to make use of this potential, this article shows a concept for integration of all phases of the RFLP approach into a tool for customization of adaptation construction
Keywords: Model Based Systems Engineering; RFLP; Design for X

Konzept für eine simulationsgetriebene-wissensbasierte Produktentwicklung im Umfeld mechatronischer Produkte - Breitsprecher, Thilo; Röhner, Sebastian; Wartzack, Sandro (Design for X. Beiträge zum 21. DfX-Symposium, 2010)
UnivIS-Import:2015-04-16:Pub.2010.tech.FT.FT-KLMEFK.konzep_3

Konzept für ein VR-System zur intuitiven Modellierung durch natürliche Interaktion - Fechter, Marius; Wartzack, Sandro (Beiträge zur virtuellen Produktentwicklung und Konstruktionstechnik, 2016)
Durch den Einsatz von virtueller Realität (VR) eröffnet sich die Möglichkeit zur Entwicklung intuitiver Interaktionsmethoden, die dem Produktentwickler erlauben, natürlich mit den virtuellen Modellen umzugehen. Dazu wird in diesem Beitrag ein System konzipiert, aufgebaut und angewendet mit dem sich Komponenten innerhalb eines CAD-Systems durch Abhängigkeiten zusammenfügen lassen. Dabei werden Verfahren zum markenlosen Finger-Tracking sowie eine aktuelle VR-Brille verwendet. In einer Fallstudie wird abschließend die Anwendbarkeit des Hard- und Softwaresystems demonstriert. Link zu einem Video zur Veröffentlichung: https://vimeo.com/159390784
Keywords: Virtual Reality; CAD; Natural User Interface

Konzept für ein wissensbasiertes FEA-Assistenzsystem zur Unterstützung konstruktionsbegleitender Simulationen - Kestel, Philipp; Wartzack, Sandro (Beiträge zum 26. DfX-Symposium, 2015)
Computer-based simulation techniques such as finite element analysis gain huge attention in engineering design practice. However, an efficient use of simulation requires an early application in the product development pro-cess. Furthermore, extensive specialist knowledge is a crucial prerequisite to perform reliable and meaningful simulations. Due to time constraints, design accompanying simulations are performed only rarely by experienced simula-tion engineers or, if they are performed by less experienced users, are not sufficiently accurate. Hence, this paper presents a concept for a knowledge-based FEA assistance system for designers to efficiently capture and provide necessary knowledge of simulation experts in early development phases.

Konzeption biomechanischer digitaler Senioren-Menschmodelle zur Anwendung in der altersgerechten Produktentwicklung - Miehling, Jörg; Geißler, Bastian; Wartzack, Sandro (Stuttgarter Symposium für Produktentwicklung (SSP) 2013, 2013)
Aufgrund des demographischen Wandels wird die Entwicklung von Produkten, die auch von älteren Menschen nutzbar sind, immer wichtiger. Heutzutage sollen Produkte zunehmend nach dem Grundsatz der virtuellen Produktentwicklung, nämlich möglichst ohne physische Prototypen, entwickelt werden. Dieser Ansatz soll helfen die Kosten und den Zeitbedarf, die in der Entwicklung und Herstellung anfallen, zu reduzieren sowie die Qualität der Endprodukte zu erhöhen. In der menschzentrierten Produktentwicklung kommen dafür biomechanische digitale Menschmodelle zum Einsatz, welche jedoch meist nur einen Durchschnittsmenschen abbilden. Dieser Beitrag zeigt eine Methodik um die Parameter, die zur Anpassung der muskuloskeletalen Modelle an unterschiedliche Alters- und Leistungsklassen notwendig sind, abzuleiten, damit diese schließlich zur Entwicklung altersgerechter Produkte herangezogen werden können. Der Konzeptionsprozess umfasst die Modifikation von Anthropometrie, Muskelkräften, Beweglichkeit und Bewegungsgeschwindigkeit basierend auf Literaturwerten oder auch Messungen an realen Versuchspersonen.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.konzep
Keywords: Altersgerechte Produktentwicklung; Virtuelle Methoden; Digitale Menschmodelle; Biomechanik

Konzeption eines Assistenzsystems für die modulare und datengetriebene Entwicklung elektrischer Antriebe - Tüchsen, Johann; Koch, Matthias; Schleich, Benjamin; Wartzack, Sandro (VDI-Berichte 2333, 2018)
Die Automobilindustrie ist geprägt von immer kürzeren Entwicklungszeiten bei gleichzeitig steigenden Funktions- und Qualitätsansprüchen. Um diese Herausforderungen zu bewältigen ist es notwendig, die Effizienz der Entwicklungsabteilungen durch Automatisierung zu steigern. In dieser Arbeit wird daher die Konzeption eines Assistenzsystems für die modulare und datengetriebene Entwicklung elektrischer Antriebe basierend auf der Methodik des V-Modells und der wissensbasierten Produktentwicklung dargestellt. Für die digitale Transformation der Produktentwicklung werden auf Basis des Zielprozesses Arbeitsschritte in Module unterteilt, welche parallel mit definierten Schnittstellen bearbeitbar sind. Mithilfe des vorgestellten Konzepts können Anfragen von Kunden schneller und mit höherem Reifegrad beantwortet werden. Die intelligente Logik im Assistenzsystem verwaltet dabei die Entwicklungs- und Produktionsdaten und steuert jedes Modul an, sobald alle Daten in ausreichender Güte vorhanden sind. So werden die Kommunikationswege verkürzt und sämtliche entwicklungsrelevante Informationen können jederzeit abgerufen werden. Weiterhin erhält der Entwickler die Möglichkeit, verschiedene Motoren digital miteinander zu vergleichen, mit verschiedenen Optima zu gewichten und letztlich das finale Produkt auszuwählen. <br

Konzept zur Auslegung beschichteter Bauteile im Wälz-Gleit-Kontakt - Tremmel, Stephan; Wartzack, Sandro; Meerkamm, Harald (Tagungsband zur 51. Tribologie-Fachtagung der GfT: : Reibung, Schmierung und Verschleiß. Forschung und praktische Anwendung, 2010)
Tribologische Schichten können als ein Konstruktionselement angesehen werden, welches es auszulegen gilt. In dem beschriebenen Auslegungskonzept wird der vorhandene, komplexe Beanspruchungszustand im Schicht-Substrat-Verbund auf der Grundlage von FE-Kontaktspannungssimulationen unter Zuhilfenahme der Vergleichsspannung nach von Mises ermittelt. Der damit einhergehende Informationsverlust über den Grad der Mehrachsigkeit des Spannungszustandes – welcher wiederum maßgeblichen Einfluss auf die Beanspruchbarkeit des Schicht-Substrat-Verbundes besitzt – wird kompensiert durch die Berücksichtigung des Mehrachsigkeitsquotienten nach Clausmeyer. Die Beanspruchbarkeit wird in relativ einfachen Schwingversuchen an ausgewählten Probekörpern unter definierten Beanspruchungszuständen ermittelt. Auf Grundlage dieser Versuche kann eine verallgemeinerbare Grenzspannungskurve für den Schicht-Substrat-Verbund in Abhängigkeit des Mehrachsigkeitsquotienten aufgestellt werden. Somit ist es möglich, für unterschiedliche Anwendungsfälle an beliebigen Punkten im Kontaktbereich „lokale Sicherheiten“ zu definieren und „kritische Orte“ zu erkennen. Diese „kritischen Orte“ müssen nicht unbedingt an der Stelle der größten Vergleichsspannung liegen. Tatsächlich stellt man auch in der Praxis fest, dass Schicht-Substrat-Verbünde im Wälz-Gleit-Kontakt nicht zwangsläufig am Ort der größten Vergleichsspannung versagen.
UnivIS-Import:2015-04-16:Pub.2010.tech.FT.FT-KLMEFK.konzep
Keywords: Schichten; Auslegung; Kontaktspannungen; FE-Simulation; Vergleichsspannung; Mehrachsigkeitsquotient

Konzept zur automatischen Bauteilerkennung innerhalb der FE-Software-Umgebung mittels Künstlichen Neuronalen Netzen - Sprügel, Tobias; Wartzack, Sandro (Design for X. Beiträge zum 25. DfX-Symposium, 2014)
The Finite Element Method is a very powerful tool to enhance product quality and to reduce unnecessary and costly iterations during the product development process. However numerous errors can occur during the FE simulation. A promising way to realize precise and quick FE simulations is the comparison of the FE solution with analytical machine elements equations. This is only possible if the components in an assembly can be identified automatically. A promising way is to use the presented approach in this paper for part recognition with artificial neural networks and the use of detection surfaces.
Keywords: automatic part recognition; Artificial Neural Network; ANN; FEM; detection surface

Konzept zur Erkennung von Singularitäten in FE-Simulationen mittels Machine-Learning Algorithmen - Bickel, Sebastian; Schleich, Benjamin; Wartzack, Sandro (37. CADFEM ANSYS Simulation Conference (22719), 2019)

Konzept zur hochdynamischen Kraftregelung mit nachgiebigen Mechanismen - Mauser, Kristian; Wartzack, Sandro; Hasse, Alexander (Design for X - Beiträge zum 27. DfX-Symposium, 2016)
The traditional approach to robotics includes a stiff serial-kinematic structure. Although this solution is efficient for position control tasks, such a concept is problematic for force control. The performance of control strategies is limited amongst others by the proper inertia which sets strong boundaries to control. Here, we propose an attractive concept for the realization of force control by means of an elastic interface based on variable-stiffness compliant-mechanism. Interposition of our elastic interface between the robot free-end and end effector 'decouples' the entire robot inertia from the end effector. Furthermore, the proposed system provides a frictionless operation and offers adaptive compliance, which allows for a high range of bandwidth.
Keywords: Series elastic actuation; compliant mechanism; highly dynamic force control; variable stiffness actuator

Konzept zur Identifikation relevanter Produkteigenschaften zur Unterstützung einer positiven User Experience - Schröppel, Tina; Miehling, Jörg; Wartzack, Sandro (Entwerfen Entwickeln Erleben in Produktentwicklung und Design 2019, 2019)
Technische Raffinesse, eine hohe Funktionalität und eine gute Gebrauchstauglichkeit reichen längst nicht mehr für eine Differenzierung am Markt aus, denn sie werden oftmals vom Nutzer als gegeben vorausgesetzt. Um die Begeisterung zur Nutzung trotz gewandelter Ansprüche zu wecken, gewinnt zunehmend das positive Erleben von Technologie, also die positive User Experience, an Bedeutung. Hierbei spielt insbesondere die Interaktion mit dem Produkt eine maßgebende Rolle, denn diese muss frei von Störungen sein. Um das garantieren zu können, ist die Nutzer-Produkt-Interaktion (kurz NPI) bereits bei grundsätzlichen Gestaltungsüberlegungen einzubeziehen. Aufgrund zahlreicher Eigenschaften und Merkmale von Produkten ist dabei jedoch oftmals nicht klar, an welchen Stellschrauben über-haupt gedreht werden muss, um die NPI besser gestalten zu können. Um diesem Problem entgegen-zuwirken, stellt der vorliegende Beitrag ein erstes Konzept zur Identifikation relevanter Produkteigen-schaften basierend auf der NPI vor. Das konzeptionelle Vorgehen besteht aus mehreren Schritten. Als erstes muss der Produktentwickler diejenigen Bereiche des Produkts identifizieren, bei denen während der Nutzung eine physische oder nicht physische NPI zustande kommt. Diese einzelnen Bereiche werden anschließend präzisiert, indem diesen eine oder mehrere von maximal fünf möglichen Interaktionsarten zugeordnet wird – sie leiten sich aus den fünf menschlichen Sinnen ab. Jedem Bereich kann somit ein visueller, taktiler, geschmack-licher, hörender und/oder riechender Kontakt zugeordnet werden. Diese Interaktionsarten werden im nächsten Schritt noch einmal konkretisiert, indem der Produktentwickler ihnen vordefinierte Standar-dinteraktionen zuordnet. Für taktile Bereiche lassen sich z. B. Interaktionen wie das Greifen, Drücken oder Drehen auswählen. Vorteil dieser Standardinteraktionen ist es, dass selbst komplexe Vorgänge als Kombination mehrerer einfach zu handhabender Interaktionen dargestellt werden können. Sind die allgemeinen Interaktionsbereiche identifiziert, die Interaktionsarten zugeordnet und die Standar-dinteraktionen ausgewählt, kann nun die eigentliche Ableitung relevanter Produkteigenschaften erfol-gen. Dies erfolgt auf Grundlage einer hinterlegten Wissensbasis, in der den einzelnen Standardinter-aktionen (z. B. Greifen) allgemeingültige und produktunabhängige Eigenschaften zugeordnet sind. Die Abfrage findet mittels einer einfachen WENN/DANN-Logik statt, in der die zur jeweiligen Standardin-teraktion gehörenden Eigenschaften abgefragt werden. Die für die Wissensbasis nötigen Informatio-nen kommen aus Datenbanken, Normen, Richtlinien und Konstruktionskatalogen sowie allgemein aus Ansätzen der Ergonomie und Gestaltlehre. Für die Standardinteraktion „Greifen“ ist bspw. ein sicherer Halt nötig. Um diesen gewährleisten zu können, sind Eigenschaften wie die Oberflächenbeschaffenheit und die Form der Greiffläche wichtig. Diese werden dem Produktentwickler dementsprechend als re-levant ausgegeben. Durch die anfangs durchgeführte Einteilung des Produkts in Interaktionsbereiche wird dem Anwender nicht nur angezeigt, was allgemein relevant wäre, sondern auch an welchen Stel-len des Produkts diese Informationen Berücksichtigung finden sollten. Die Kombination und Zuord-nung produktspezifischer Merkmale zu den allgemein gehaltenen Eigenschaften sind durch den An-wender am Ende nach wie vor individuell vorzunehmen. Im Rahmen des vorliegenden Beitrags wird neben der Vorstellung eines ersten Entwurfs des Konzepts das Vorgehen anhand eines kurzen Fallbeispiels verdeutlicht. Zudem werden die Potenziale und Gren-zen des Ansatzes diskutiert. Parallel wird der weiterführende Forschungsbedarf herausgearbeitet. Zusammenfassend, soll das Konzept letztlich den Produktentwickler dafür sensibilisieren, welche Ei-genschaften an welcher Stelle für eine nutzerorientierte Gestaltung des Produkts besonders wichtig sind. Damit soll die Interaktion zwischen Mensch und Technik transparenter und störungsfreier ge-macht und so eine positivere und nutzungsfreundlichere Ausgestaltung des Produkts gefördert werden.<br
Keywords: nutzerzentrierte Produktentwicklung; Produkt-Nutzer-Interaktion; Wissensdatenbank

Konzept zur Umsetzung einer zentralen Wissensbasis für Simulationswissen in ANSYS Engineering Knowledge Manager - Kestel, Philipp; Sprügel, Tobias; Katona, Sebastian; Wartzack, Sandro (ANSYS Conference & 33th CADFEM Users' Meeting, 2015)
An efficient use of Finite Element Analyses requires an early application in the product development process. Furthermore, extensive specialist knowledge is a crucial prerequisite to perform reliable and meaningful simulations. However, due to the strongly expanding field of application, Finite Element Analyses are increasingly performed by less experienced simulation users. Against this background, the objective of the Bavarian Research Association FORPRO² is to enhance virtual product and process development through strategically planned and operationally supported simulations. For this purpose the required expert knowledge is compiled in a structured and suitable manner and provided targeted through a central knowledge base. ANSYS Engineering Knowledge Manager (EKM) offers high potential to handle and context-sensitively apply the wide range of necessary simulation knowledge in versatile fields of application. This knowledge ranges from modeling rules for recurring components in product and process simulations depending on the development stages and tasks through to analytical equations for checking the plausibility of simulation results. In this presentation a concept for the implementation of a context-sentive knowledge-base in EKM for simulation knowledge will be presented.
UnivIS-Import:2015-10-26:Pub.2015.tech.FT.FT-KLMEFK.konzep

Konzept zur Verbesserung des realitätsgetreuen, visuellen Erlebens in virtuellen Umgebungen durch Eye-Tracking - Gerschütz, Benjamin; Fechter, Marius; Schleich, Benjamin; Wartzack, Sandro (Entwerfen Entwickeln Erleben in Produktentwicklung und Design 2019, 2019)
Ein positives Nutzungserlebnis (engl. User Experience) ist einer der Schlüsselaspekte erfolgreicher Produkte und damit auch die Grundlage für den wirtschaftlichen Erfolg des Unternehmens. Ergonomische Bedienbarkeit und ansprechende Gestaltung des Produkts haben hierauf einen starken Einfluss. Entwickler und Designer versuchen deshalb, dieses Erlebnis bereits in einer möglichst frühen Phase des Produktenwicklungsprozesses zu erfassen und zu bewerten. Ein in der Automobilbranche erfolgreich eingesetztes Werkzeug zur Bewertung des Nutzererlebnisses ist der Prototypenbau. Der Einsatz von Prototypen ist allerdings mit einem hohen zeitlichen und finanziellen Aufwand verbunden und erst in späteren Phasen des Produktentwicklungsprozesses möglich. Zu diesem Zeitpunkt können Produktänderungen einen hohen zeitlichen und finanziellen Mehraufwand bedeuten. Im Sinne des „Frontloadings“ ist es daher wünschenswert, für die Bewertung des Nutzererlebnisses früh zur Verfügung stehende, digitale Modelle zu nutzen. Damit können frühzeitig erste Erkenntnisse über das Nutzungserlebnis unterschiedlicher Konzepte in die Entwicklung des Produkts einfließen. Durch Einsatz von Methoden der Virtuellen Realität (VR) besteht die theoretische Möglichkeit, eine Bewertung des Produkts hinsichtlich Design und Ergonomie bereits in frühen Phasen des Produktentwicklungsprozesses durchzuführen. Jedoch besteht bei der visuellen Wahrnehmung von Größe, Distanz und Form in einem Head-Mounted Display (HMD), insbesondere im Nahbereich, eine signifikante Diskrepanz zwischen der virtuellen Darstellung eines Modells und dessen realen Aufbaus. Die Ursachen dieser Wahrnehmungsdiskrepanzen konnten in bisherigen empirischen Studien nicht exakt festgestellt werden. Im Allgemeinen werden diese mit fehlenden Tiefenhinweisen oder Abweichungen in zur Berechnung der visuellen Darstellung verwendeten Parametern, wie dem Sichtfeld oder dem Pupillenabstand, erklärt. Als Folge der vorhandenen Diskrepanz zwischen der gewünschten und der erzielten Darstellung, sind Ergebnisse aus virtuellen Studien, insbesondere für die Evaluierung ergonomischer Aspekte wie der Erreichbarkeit einzelner Bedienelemente, nur bedingt belastbar. Bisher verwenden die meisten HMDs eine vereinfachte Modellbildung zur Berechnung der visuellen Darstellung von Objekten. Es wird über die räumliche Lage des Kopfes auf die Positionen der Pupillen geschlossen, anstatt die exakten Pupillenpositionen heranzuziehen. Durch den Einsatz von Eye-Tracking innerhalb von HMD‘s eröffnet sich die Möglichkeit, die genaue Pupillenposition bei der Berechnung der visuellen Darstellung zu berücksichtigen. In diesem Beitrag wird ein Konzept vorgestellt, um das Potential des Eye-Trackings zur Erzeugung realitätsgetreuer, visueller Reize zu nutzen. Hierzu erfolgt die Betrachtung verschiedener Tiefenhinweise, die bei der Wahrnehmung im Nahbereich dominanten Einfluss besitzen und in bisherigen technischen Lösungen unzureichend angesprochen werden. Zusätzlich wird der Einfluss der Verzerrung der im HMD verbauten Linsen auf die Blickrichtungsabhängigkeit der Darstellung anhand eines Demonstrators zur Simulation von Linsenbrechung in HMDs aufgezeigt. Ausgehend von den beschriebenen Faktoren werden Lösungskonzepte präzisiert um die Einschränkungen zu überwinden. Der Beitrag endet mit einer Zusammenfassung sowie einem Ausblick auf nachfolgende Schritte zur Überwindung der Wahrnehmungsdiskrepanzen um ein realitätsgetreues, visuelles Nutzungserlebnis des Produkts zu ermögliche
Keywords: visuelle Wahrnehmung; Virtual Reality; Eye-Tracking; Head-Mounted-Display; User Experience

Konzept zur zielgerichteten, ontologiebasierten Wiederverwendung von Produktmodellen - Kestel, Philipp; Luft, Thomas; Schon, Claudia; Kügler, Patricia; Bayer, Thomas; Schleich, Benjamin; Staab, Steffen; Wartzack, Sandro (Design for X. Beiträge zum 28. DfX-Symposium, 2017)
The reuse of product and process models during the product development process leads to considerable savings of costs and time. Such models are available in digital form in data and knowledge bases. However, the successful reuse of these models also requires the removal of model elements that do not apply to the new product. These removal processes are not yet supported by procedure models or IT systems. Up to now, the direct deletion of model elements by product developers leads to inconsistent and fragmentary knowledge bases or retention of unnecessary data. Thus, the aim of this contribution is to facilitate the reuse of product and process models by adding methods for the efficient removal of obsolete model elements to the existing IT systems.
Keywords: Product Data Management; Knowledge-based Engineering; Ontology-based knowledge representation; Intentional Forgetting

Kraftflussgerechte Fused Layer Modeling-Strukturen mit kurzfaserverstärktem Filament - Völkl, Harald; Steck, Patrick; Franz, Michael; Wartzack, Sandro (Konstruktion, 2020)
Additive manufacturing processes such as Fused Layer Modeling (FLM) offer a high degree of design freedom exploited by Design for Additive Manufacturing (DfAM). The present paper proposes a systematic approach for design and simulation of load path optimised FLM structures, comprising four steps: 1. Topology optimisation with orthotro-pic material model generates a load-path-optimised structure and provides optimised material orientations. 2 . The obtained optimisation results are converted into extrusion paths for FLM printers. 3. Printer specific building source is generated. 4. A structural mechanics FE simulation allows to determine the lightweight potential exploited.
CRIS-Team Scopus Importer:2021-04-19

Kraftflussgerechte Fused Layer Modeling-Strukturen mit kurzfaserverstärktem Filament - Völkl, Harald; Steck, Patrick; Franz, Michael; Wartzack, Sandro (Konstruktion, 2020)
Additive Fertigungsverfahren wie Fused Layer Modeling (FLM) bieten hohe Designfreiheiten, die sich durch Design for Additive Manufacturing (DfAM) nutzen lassen. Der vorliegende Beitrag schlägt ein vierschrittiges, systematisches Vorgehen zur Erzeugung und Simulation lastpfadgerechter FLM-Strukturen vor: 1. Eine Topologieoptimierung mit orthotropem Materialmodell erzeugt eine lastpfadoptimierte Struktur und Materialorientierungen. 2. Die gewonnenen Optimierungsergebnisse werden in Extrusionspfade für FLM-Drucker umgesetzt. 3. Druckerspezifische Building Source wird generiert. 4. Eine strukturmechanische FE-Simulation erlaubt die Ermittlung des ausgeschöpften Leichtbaupotential

Kritische Würdigung eines Werkzeugs zur Messung von Nutzerexklusion im Produktdesign. - Kett, Susan; Ringler, Alexander; Kamin, Stefan; Lang, Frieder; Wartzack, Sandro (Design for X. Beiträge zum 26. DfX-Symposium., 2015)
Inclusive Design strategies are of growing interest to companies serving heterogeneous users, e.g. in the mobile phone market. Therefore, several tools to assess physical and cognitive exclusion exist. The authors outline that with the maturation of physical inclusion management, there is an upcoming deficit in non-physical inclusion such as social or psychological astigmatisa-tion. Therefore, a brief overview of user perception and the different ap-proaches of Inclusive Design are given to outline hitherto existing knowledge. Research needs are illustrated by using an inclusive design tool measuring exclusion through product usability. The author’s suggestions lead to an al-ternative approach including soft factors addressing non-stigmatic design. Concluding, the main findings during this study are presented.
Keywords: inclusive design; user characterization; user centered design

KTmfk gewinnt Ingenieure ohne Grenzen Challenge 2021 - Wartzack, Sandro; Bartz, Marcel; Miehling, Jörg; Rothammer, Benedict; Hufnagel, Thomas; Scherb, David; Wilking, Fabian; Wirsching, Sven (WiGeP News, 2021)

Laser based techniques to adapt the tribological conditions in dry deep drawing - Vorndran, Martin; Häfner, Tom; Rothammer, Benedict; Krachenfels, Kim; Merklein, Marion; Tremmel, Stephan; Schmidt, Michael (International Conference on Advanced Optical Technologies, 2019)
Sheet metal forming is widely used in industry to transform a flat metal sheet to a final shape. However, sheet metal forming requires the use of lubricants to prevent the direct contact between tool and workpiece. These lubricants are often toxic and have to be removed after the forming process. Therefore, the environment and the process chain will profit from the abandonment of lubricants. The use of tool sided coatings is a well-known approach to substitute lubricants and perform dry deep drawing. To achieve satisfying results in deep drawing it is beneficial to tune the tribological conditions. Here, we show laser based techniques to locally adapt the tribological conditions by either reducing the roughness of the surface or by creating structures within the surface. It is e.g. shown that the reduced peak height of coated surfaces can be decreased by a laser process. Furthermore, the resulting tribological conditions are investigated for zinc coated DC04 and AA5162 specimens. In Addition to the tribological behavior the changes of the chemical coating properties are investigated using Raman spectroscopy.<br

Least Cost Tolerance Allocation for Systems with time-variant Deviations - Walter, Michael; Sprügel, Tobias; Wartzack, Sandro (Procedia CIRP, 2015)
This paper presents a methodology for the least cost tolerance allocation of systems with time-variant deviations, such as deformation, thermal expansion, mobility of parts and wear. By means of the approach, the product developer can identify the system’s optimal tolerance design against the backdrop of the diverging requirements: wide tolerances to reduce costs vs. narrow tolerances to ensure functionality. Therefore, Particle Swarm Optimization – a global statistical optimization technique – is applied to the time-variant tolerance-optimization problem to determine the tolerance range as well as a certain mean shift for each non-ideal dimension. The practical use of the methodology is illustrated for a modified tolerance stack-up problem. We provide a comprehensive walkthrough of the methodology’s application to the stack-up problem. Therefore, the essential mathematical background, the required functional dependencies and the considered parameters are detailed in a step-by-step procedure. So, we aim to establish the application of the statistical tolerance-costoptimization in academia and industry and to motivate students and young graduates to apply this methodology by themselves.
Keywords: tolerance allocation; time-dependent mechanisms; deformation; thermal expansion; particle swarm optimization

Lebenszyklusorientierte Toleranzsimulation zur funktionalen und ästhetischen Produktabsicherung - Wartzack, Sandro; Meerkamm, Harald; Stockinger, Andreas; Stoll, Tobias; Stuppy, Julia; Voß, Ralf; Walter, Michael; et al. (Konstruktion, 2011)
Die Toleranzsimulation ist ein wichtiges Werkzeug in der Produktentwicklung zur frühzeitigen Bestimmung der Auswirkungen von Abweichungen, bevor diese an der realen Baugruppe auftreten. Die in diesem Beitrag vorgestellten Forschungsarbeiten beschränken sich dabei nicht auf die in der Toleranzsimulation typischerweise betrachtete Montage, sondern sie untersuchen den gesamten Produktlebenszyklus von der Produktentwicklung und der dort notwendigen Toleranzspezifikation über die Fertigung und die Montage bis zur Produktnutzung. Für all diese Phasen werden Methoden und Werkzeuge vorgestellt, die am Lehrstuhl für Konstruktionstechnik der Universität Erlangen-Nürnberg innerhalb der letzten fünf Jahre entwickelt wurden und das Toleranzmanagement während der Produktentwicklung unterstützen.
UnivIS-Import:2015-03-09:Pub.2011.tech.FT.FT-KLMEFK.lebens

Lifetime and Degradation of Pre-damaged PV-Modules - Field study and lab testing - Buerhop, Claudia; Wirsching, Sven; Gehre, Simon; Pickel, Tobias; Winkler, Thilo; Bemm, Andreas; Mergheim, Julia; Camus, Christian; Brabec, Christoph; Hauch, Jens (Conference record of the IEEE Photovoltaic Specialists Conference, 2017)
The presence of pre-cracked PV-modules in modern PV-plants is well-known. The evolution and actual impact of the cracks on electrical yield under real operation conditions is not yet understood but of great relevance. Established standards cannot reveal the relevant effects. Therefore, a unique threefold analysis is applied: 1) field exposure, 2) using a new accelerated loading test, and 3) Finite Elements (FEM) simulations. For the first time, we present comparative Electroluminescence (EL-) images recorded in the field and during load testing. Crack growth is studied in terms of the monitored weather conditions and the applied load simulating static snow and wind loads.

Linking a game-engine with CAD-software to create a flexible platform for researching extended reality interfaces for the industrial design process - Harlan, Jakob; Schleich, Benjamin; Wartzack, Sandro (31st Symposium Design for X (DFX2020), 2020)
Driven by the need to develop highly complex products in short development cycles, many companies are aiming at fully digitized design workflows and continuous data and information flow. XR-interfaces can extend current CAD-functionality to allow the usage of CAD-data in more stages of the product design process. In this paper, a platform linking a game-engine and CAD-software to efficiently explore XR-CAD Interfaces is presented. An architecture meeting the requirements of research environments is designed and implemented using the unreal engine and Siemens NX. The proposed system allows to efficiently explore interfaces for design sketch creation using different hardware setups.<br
Keywords: Virtual Reality; Extended Reality; Computer-Aided-Design; Natural-User-Interface

Local adaptation of aluminum blanks through laser de-alloying and wire alloying - Stephan, Marcel; Zieroth, Henrik; Samland, Simona; Bartels, Dominic; Merklein, Marion; Schmidt, Michael (SheMet2025, 2025)
Abstract. The 7xxx series aluminum alloys, renowned for their exceptional specific strength, are promising materials for automotive manufacturing. Despite their advantages, the widespread application of these alloys is inhibited by their low formability. The high strength but low formability is caused by Zn and Mg precipitations, which hinder dislocation motion. In this study, the local adaption of the elemental composition of aluminum blanks through selective evaporation and alloying via auxiliary wire is investigated. A high-power laser is used for melting and evaporating low boiling elements such as Mg and Zn while adding AlSi5 in parallel to improve formability in the forming zone. The resulting element distribution is studied and correlated with the applied process conditions, to gain an insight on the possibilities and limitations of the laser induced alloy adaptio
Keywords: Laser Welding; Aluminum; Hybrid Manufacturing

Lubricant free forming with tailored tribological conditions - Henneberg, Johannes; Rothammer, Benedict; Zhao, Rong; Vorndran, Martin; Tenner, Jennifer; Krachenfels, Kim; Häfner, Tom; Tremmel, Stephan; Schmidt, Michael; Merklein, Marion (Dry Metal Forming Open Access Journal, 2020)
Changed ecological and economic situations motivate research into environmentally friendly and efficient manufacturing processes. Forming without lubricant has the potential to meet both requirements by avoiding the usage of environmentally harmful lubricants and shortening the process chain by omitting lubricant application and component cleaning. Within the scope of the project, an increase in friction and adhesive wear were identified as major challenges, resulting in failure of components due to cracking. Therefore, this project focused on the investigation of measures to meet these challenges. Amorphous carbon coatings, the reduction of roughness and the application of discrete microtextures were considered as potential measures. Hydrogen-containing amorphous carbon coating systems (a-C:H) fabricated by reactive physical vapor deposition (PVD), plasma-enhanced chemical vapor deposition (PECVD) and PVD/PECVD hybrid techniques, as well as a PVD-generated tetrahedral hydrogen-free amorphous carbon coating (ta-C) were investigated with respect to their properties and tribological performance Three specific profile requirements –a dopant free carbon network, smooth and defect-free surfaces and a high coating adhesion to substrate –are identified as requirements, in order to prolonger the service life of the coated tools. Moreover, to enable the steering of the material flow ultrafast laser based micro texturing for locally tailored tribological conditions were investigated. Thereby two wavelength dependent ablation regimes which differ in ablation mechanism and freedom of form were identified. Using these approaches the friction coefficient could either be reduced by up to 20 % or selectively increased. To improve the efficiency of the process, several beam shaping approaches were evaluated to provide a homogeneous beam profile for uniform modification. By applying ta-C and a-C:H coatings in forming tests, the findings of the laboratory tests were validated and the feasibility of lubricant free deep drawing was proven. In order to benefit from the forming-process-specific advantages, high quantities and therefore high durability of the measures are required. An application-oriented wear test rig has been designed to investigate their durability. By this, it was proven that 3 000 components can be produced from DC04 without wear with both a-C:H and ta-C coatings, and thus increasing tool life by a factor of 15 compared to unmodified tools. Even in the case of wear-critical AA5182, 3 000 parts were produced without wear using ta-C. Within the scope of the project, a fundamental understanding of lubricant free deep drawing processes and measures was created and proof of feasibility in form of a high number of components was achieved.<br
Keywords: Dry Deep Drawing; Tribology; Carbon Based Coatings; Laser Based Surface Modification; Beam Shaping

Lubrication Mechanisms in Knee Joint Replacements: A Comprehensive Experimental Investigation - Nečas, David; Vrbka, Martin; Marian, Max; Rothammer, Benedict; Gallo, Jiří; Wimmer, Markus A; Křupka, Ivan; Hartl, Martin (International Tribology Conference Fukuoka 2023, 2023)

Lubrication of Hip and Knee Joint Replacements: The Contribution of Experiments and Numerical Modeling - Nečas, David; Marian, Max; Sawae, Yoshinori (Biotribology: Emerging Technologies and Applications, 2021)
The longevity of hip and knee joint replacements is considerably affected by the overall (bio-) tribological performance. Wear particles released during joint articulation harm the surrounding tissues, leading to biochemical degradation, and eventually causing an implant loosening with the subsequent need for revision. Thereby, wear is substantially influenced by synovial fluid lubrication phenomena. Over the last two decades, significant knowledge about lubrication mechanisms in artificial joints has been gained, thanks to experimental investigations and numerical modeling. Various model configurations were extensively tested using electrical and optical methods, usually focusing on film thickness analysis. Attention was paid not only to contact mechanics and valid dynamic conditions but also to the behavior of mimicked synovial fluid and the role of specific constituents, such as proteins, hyaluronic acid, or phospholipids. Concerning film formation prediction, various numerical approaches based upon multigrid/-level integration and the finite difference or the finite element method have been developed. Although the Reynolds equation was usually used to describe hydrodynamics, the variety of approaches have apparent differences in terms of underlying assumptions, numerical implementation, and applicability to simulating hip or knee joint. Numerical modeling was utilized to analyze the influence of rheological properties of the synovial fluid, material characteristics or load, and kinematics on the tribological behavior, as well as to optimize macro- and micro-geometry. Due to the limited ability to obtain insights into the corresponding in vivo lubrication mechanisms, experimental in vitro studies should always be carried out with a close linkage to numerical modeling to ensure validity and transferability. Therefore, the following chapter aims at providing a comprehensive overview of the relevant methods and approaches when revealing lubrication mechanisms of joint replacements. At the end of the chapter, the main findings are summarized while some suggestions for future research directions are derived.<br

Lücken und Herausforderungen bei der praktischen Umsetzung des Model-Based Systems Engineering - Fresemann, Carina; Stark, Rainer; Sauer, Christopher; Schleich, Benjamin; Wartzack, Sandro (Konstruktion, 2019)
Im Rahmen der Zusammenarbeit der Friedrich-Alexander-Universität Erlangen-Nürnberg und der Technischen Universität Berlin wurde eine interaktive Studie mit 20 Experten aus großen und kleinen Unternehmen aus dem deutschsprachigen Raum durchgeführt. Ein Ziel der Studie war die Feststellung von Lücken und Herausforderungen, welche die bereits seit einigen Jahren bestehenden wissenschaftlichen Erkenntnisse und damit verbundene neue digitale Fähigkeiten in der industriellen Praxis limi- tieren. Der vorliegende Artikel beschreibt sowohl das Vorgehen als auch die Erkenntnisse der Studie. Darüber hinaus leitet sich weiterer Handlungsbedarf a

"MAGMAKegel": Simulation abweichungsbehafteter Kegelrollenlager - Aschenbrenner, Alexander; Schleich, Benjamin; Tremmel, Stephan; Wartzack, Sandro; Stahl, Thomas (Konstruktion, 2019)
Kegelrollenlager eignen sich hervorragend für tragfähige und führungsgenaue Lagerungen. Wie jedes reale Bauteil unterliegen jedoch auch Kegelrollenlagerkomponenten Maß-, Form- und Lageabweichungen. Diese Abweichungen haben Einfluss auf das Betriebsverhalten von Kegelrollenlagern. In einer Kooperation mit Schaeffler Technologies AG & Co. KG hat der Lehrstuhl für Konstruktionstechnik der Friedrich-Alexander-Universität Erlangen-Nürnberg das Softwarewerkzeug MAGMAKegel entwickelt, mit welchem sich Toleranzanalysen durchführen lassen, um ebendiese Auswirkungen geometrischer Abweichungen auf Kegelrollenlager zu quantifizieren. Im vorliegenden Beitrag wird das Softwarewerkzeug genauer beschriebe

Making a difference: Integrating physiological and psychological needs in user description - Schröppel, Tina; Wartzack, Sandro (Proceedings of NordDesign 2018, Linköping, Sweden, 14th - 17th August 2018, 2018)
Products particularly designed to support physically impaired people often contain for example big buttons in order to remain easy to use and handy for users suffering from diseases like rheumatism, multiple sclerosis or others. There is for example a reported prevalence of more than 31 million people with rheumatoid arthritis in Europe. This condition most commonly affects the joints of the hands. However, the sales volume of specially designed products does not reflect this number of affected people. This discrepancy can result from the design of these products. First of all, they often look very unattractive. In addition, the design itself strongly implies the context of physically impaired people. This fact can lead to negative user stigmatization, which usually makes the user feel uncomfortable. Thus, it seems that subjective quality aspects are from rising importance when it comes to product usage. However, there is a gap between the consideration of physiological and psychological user demands that needs to be filled. In consequence, this gap is to be closed and both demands are to be taken into account equally. Therefore, better products can be designed for individual people. Especially physically impaired persons, which have a high demand of subjective quality, will benefit from those products. Literature already includes various methods for psychological and physiological user description. Physiologically there are norms, standards or medical tests for instance. On a psychological perspective, several methods like affective priming or the use of semantic differentials allow a better understanding of the user’s attitude. Therefore the question arises, whether there are existing methods suitable to consider physiological and psychological needs in combination. This paper examines, whether there are qualified approaches that can be used to efficiently identify and compare psychological and physiological user needs. Therefore, it also interprets the compatibility between both types of user needs. Thus, this paper provides a solid base for developing a novel and integrated user-centered design approach that efficiently combines physiological and psychological user needs to improve the development of future products.<br
Keywords: subjective user needs; physiological user needs; user stigmatization; integrated user centered design

Mapping of GD&T information and PMI between 3D product models in the STEP and STL format - Hallmann, Martin; Götz, Stefan; Schleich, Benjamin (Computer-Aided Design, 2019)
Increasing specialization of design, manufacturing, assembly, and inspection have fostered the need for sophisticated product documentation practices to allow the clear and unambiguous communication of product information between design and all downstream activities. This need has led to the development of various standards for the exchange of product geometry and related information and particularly to the emergence of STEP as a standard for the exchange of product model data. Though STEP is widely used as an exchange format in design and related domains, other standards and file formats are frequently used for transferring product geometry information from design to downstream activities today, such as the STL (Standard Tesselation Language) format, which uses a discrete geometry representation scheme for describing part geometry by an unstructured triangulated surface. However, there exists a gap between STEP, which offers great benefits regarding the documentation of nominal product geometry and product manufacturing information, and the STL format, which offers a discrete geometry representation by triangles. With the aim to close this gap, this paper presents a novel method that allows an automatic mapping of PMI (Product and Manufacturing Information) and GD&T (Geometric Dimensioning and Tolerancing) information assigned on the CAD model from STEP files on discrete geometries. The method comprises the interpretation of ISO STEP AP 242 files as well as a novel feature recognition approach. The combined data model, that represents the geometry in tessellated format and includes the GD&T information assigned on the triangulated features, may then serve as an interface model between design, simulation, manufacturing, and inspection and thus contributes to the consistency of product documentation throughout the digital thread in the product life-cycle. The applicability of the method is highlighted using a case study of a car brake system of industrial complexity. In addition, its benefits are underlined by the exemplary application of the method in the context of injection molding simulation and tolerance analysis.
Keywords: STEP; PMI; STL; GD&T; Feature recognition

Markerlose Bewegungsaufzeichnung und Bewertungsmethoden für die menschzentrierte Produktentwicklung - Miehling, Jörg; Wartzack, Sandro (Beiträge zum 23. DfX-Symposium, 2012)
Human-centered design focuses on the adaption of product specifications to meet the users’ requirements. In order to save development time, reduce product development costs as well as to enhance the products’ quality, the virtual product development paradigm emphasizes the use of virtual prototypes instead of physical ones. To meet these objectives a digital human modeling system is needed which is capable of representing the human-product interaction. Up to now it is not possible to accurately model real motion sequences at the computer, thus motion capturing is needed. The presented contribution illustrates a system for the markerless tracking of human body movements, which can be used to drive biomechanical simulations, using Microsoft’s Kinect sensor. Additionally further directions for the development of a system to evaluate and visualize the resultant simulation data are outlined.
UnivIS-Import:2015-04-16:Pub.2012.tech.FT.FT-KLMEFK.marker
Keywords: Motion Capturing; Menschmodell; Microsoft Kinect; menschzentrierte Produktentwicklung; virtuelle Produktentwicklung

Maschinelles Lernen zur schallemissionsarmen Entwicklung von Maschinen - Wartzack, Sandro; Küstner, Christof (WiGeP News, 2017)
Maschinelles Lernen zur schallemissionsarmen Entwicklung von Maschinen: Prognose und Reduzierung der Schallemission am Beispiel von Windenergieanlagen

Maßgeschneidertes Model-based Systems Engineering - Wartzack, Sandro (Konstruktion, 2020)
CRIS-Team Scopus Importer:2021-04-19