Characterization of a Si and GaN converter at cryogenic temperatures - Büttner, Stefanie; Nowak, Alexander; März, Martin (Cryogenics, 2022)
The efficiency improvement of a Si-MOSFET and GaN-HEMT synchronous buck converter at low temperatures is demonstrated and discussed in detail. By carefully selecting suitable components for cryogenic temperatures and characterizing them from room temperature to low temperatures, the functionality of each component is demonstrated before cryogenic operation of the entire converter and the impact of the component properties on the total losses are considered. Overall, a power loss reduction of up to 60% could be achieved with both converters at 87 K compared to losses at room temperature. Thereby, the conduction losses of the transistors as well as the DC winding losses of the inductor have the greatest impact on loss reduction at low temperatures.<br

Charakterisierung von Ermüdungsschäden bei Wälzlagern unter Schwenkbewegungen - Halmos, Fabian; Bartz, Marcel (64. Tribologie-Fachtagung der Gesellschaft für Tribologie e.V., 2023)

CO2 as a Viscosity Index Improver for Wind Turbine Oils - Pohrer, Benjamin; Zürcher, Manuel; Westerholt, Antje; Bösmann, Andreas; Siebert, Daniel; Völkl, Johannes; Holweger, Walter; Wehrum, Natalie; Arlt, Wolfgang; Wasserscheid, Peter; Schlücker, Eberhard (Industrial & Engineering Chemistry Research, 2015)
A high viscosity index (VI) is crucial for lubricants in industrial gearboxes exposed to changing load or weather conditions. Especially in the field of wind turbine oil, viscosity indices of 150 or higher are demanded to reduce power losses and ensure reliability at the same time. In this context, the use of dissolved CO2 to improve viscositytemperature behavior has been investigated for task-specific, halogen-free ionic liquids and benchmarked against poly(alpha-olefins). By measuring the viscosity and density of the lubricants with dissolved CO2, it was proven that the VI can be increased significantly, even at moderate pressures. In addition, measurements and simulation on CO2 solubility and studies on corrosion and tribology under CO2 pressure are presented.

Coated polymers for low friction and wear of roller bearing cages in lightweight design - Sander, Thomas; Vierneusel, Bernd; Tremmel, Stephan; Wartzack, Sandro (ICMCTF 4th Anniversity, 2013)
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.coated

Combination of Matrix-based and Graph-based Modeling for Product and Organizational Structures - Schweigert, Sebastian; Luft, Thomas; Wartzack, Sandro; Lindemann, Udo (Understand, Innovate, and Manage your Complex System! Proceedings of the 19th International DSM Conference, 2017)
As a consequence of volatile markets and agile development processes, products and organizational structures have become increasingly complex. Modeling and analyzing complex products and organizations via matrices and graphs are useful ways to handle this complexity. This paper combines approaches for modeling products and organizational structures with matrices on the one hand. On the other hand, graph-based methods for analyzing the dependencies within as well as between the product and organization domain are described. Combining these domains gives the possibility to improve the overall development process by minimizing iterations and by adjusting the organizational to the product structure.
Keywords: DSM; DMM; MDM; product modeling and analysis; organization modeling and analysis

Combining multi-scale surface texturing and DLC coatings for improved tribological performance of 3D printed polymers - Marian, Max; Zambrano, Dario; Rothammer, Benedict; Waltenberger, Valentin; Boidi, Guido; Krapf, Anna; Merle, Benoit; Stampfl, Juergen; Rosenkranz, Andreas; Gachot, Carsten; Grützmacher, Philipp (Surface & Coatings Technology, 2023)
Polymer components fabricated by additive manufacturing typically show only moderate strength and low temperature stability, possibly leading to severe wear and short lifetimes especially under dry tribological sliding. To tackle these shortcomings, we investigated the combination of single- and multi-scale textures directly fabricated by digital light processing with amorphous diamond-like carbon (DLC) coatings. The topography of the samples and conformity of the coatings on the textures are assessed and their tribological behaviour under dry conditions is studied. We demonstrate that the surface textures have a detrimental tribological effect on the uncoated samples. This changes with the application of DLC coatings since friction substantially reduces and wear of the textures is not observed anymore. These trends are attributed to the protection of the underlying polymer substrate by the coatings and a reduced contact area. The best tribological performance is found for a coating with highest hardness and hardness-to-elasticity ratios. Moreover, multi-scale textures perform slightly better than single-scale textures due to a smaller real contact area. Summarizing, we verified that the high flexibility and low production costs of 3D printing combined with the excellent mechanical and tribological properties of DLC results in synergistic effects with an excellent performance under dry sliding conditions.<br

Combining System Models and CAD for Change Scenario Management - Hick, Hannes; Schleich, Benjamin; Sanladerer, Stefan; Ryan, Karen; Trautner, Jessica; Piguet, Jean; Wilking, Fabian; Horber, Dennis; Faustmann, Clemens; Kranabitl, Philipp; Kollegger, Stefan; Bajzek, Matthias; et al. (33rd Annual INCOSE International Symposium, 2023)
In the development of complex mechatronic systems, interdisciplinary cooperation requires an exchange between stakeholders in order to ensure fulfillment of requirements and related functions. The cooperation of the stakeholders from different disciplines must be well coordinated to address systems changes. The system model as an essential aspect of model-based systems engineering, has to be linked to specific models of involved disciplines (mechanical, electrical/electronical and software) to enable a basis for automatic identification e.g., of affected subsystems and functions. This contribution discusses the potential of model linking from the perspective of change scenarios by considering published approaches to link system models and computer-aided design (CAD). A methodical approach on how descriptive system models can be used as base for computer-aided design is presented. This approach is analyzed by reviewing a use case for a design change scenario of an automotive eAxl
Keywords: MBSE

Comparative evaluation of WIMP and immersive natural finger interaction: a user study on CAD assembly modeling - Fechter, Marius; Schleich, Benjamin; Wartzack, Sandro (Virtual Reality, 2021)
Virtual and augmented reality allows the utilization of natural user interfaces, such as realistic finger interaction, even for purposes that were previously dominated by the WIMP paradigm. This new form of interaction is particularly suitable for applications involving manipulation tasks in 3D space, such as CAD assembly modeling. The objective of this paper is to evaluate the suitability of natural interaction for CAD assembly modeling in virtual reality. An advantage of the natural interaction compared to the conventional operation by computer mouse would indicate development potential for user interfaces of current CAD applications. Our approach bases on two main elements. Firstly, a novel natural user interface for realistic finger interaction enables the user to interact with virtual objects similar to physical ones. Secondly, an algorithm automatically detects constraints between CAD components based solely on their geometry and spatial location. In order to prove the usability of the natural CAD assembly modeling approach in comparison with the assembly procedure in current WIMP operated CAD software, we present a comparative user study. Results show that the VR method including natural finger interaction significantly outperforms the desktop-based CAD application in terms of efficiency and ease of use.
CRIS-Team Scopus Importer:2021-06-25
Keywords: Assembly modeling; Computer-aided design; Natural user interface; Virtual reality

Comparing CAD part models for geometrical similarity: A concept using machine learning algorithms - Bickel, Sebastian; Sauer, Christopher; Schleich, Benjamin; Wartzack, Sandro (CIRPe 2020 - 8th CIRP Global Web Conference -, 2020)
The efficient execution of process planning activities requires the knowledge from several distinct domains. However, in this context, a common issue is the existence of collective knowledge in the one domain with a lack of networked expertise with other domains. Motivated by this, the paper proposes an approach to support process planning by comparing the generated part design with older, validated products. The utilization of this earlier CAD part models has the potential to reduce development costs, shorten the production start-up time and improve the product quality. The new concept provides the manufacturing personnel with a method for comparing the newly designed part with a pool of validated models to identify the most similar one. Each previous CAD part model is linked with the necessary manufacturing information, so that the initial values for the manufacturing process are available without a time consuming testing phase. The method is divided in three main steps: the global similarity comparison, the segmentation of the part and the local similarity comparison. In the first step, the geometry is projected onto a sphere and then transformed to a matrix. Afterwards these matrices are compared and clustered into corresponding groups. In the following step, a Machine Learning algorithm segments the objects into specific, manufacturing relevant groups. In every cluster, the segmented geometries are again compared for similarity. The combination of the first and the second ranking results in a global similarity hierarchy for the newly designed part. In this paper, the entire procedure is shown with the example of sheet-bulk metal formed parts. This new manufacturing process particularly benefits from this method, as the amount of data is still limited and therefore little expert knowledge exists.<br
Keywords: "Digital Engineering; similarity; comparison; Machine Learning; data-driven" Abstract

Comparison of different methods for scrap rate estimation in sampling-based tolerance-cost-optimization - Hallmann, Martin; Schleich, Benjamin; Heling, Björn; Aschenbrenner, Alexander; Wartzack, Sandro (Procedia CIRP, Volume 75, 2018)
Tolerance-cost-optimizations help to find optimal tolerances for a given tolerance design, which achieve minimum total costs while satisfying the quality requirements. These requirements are commonly expressed as scrap rates in ppm-range. This paper presents several methods for the scrap rate estimation in sampling-based tolerance-cost-optimizations. Moreover, the proposed approaches are applied to a typical case study and compared in terms of their required computation time and the obtained optimization results. The novelty of the contribution can be found in comparing different scrap rate estimation techniques for sampling-based tolerance-cost-optimizations and giving recommendations to researchers as well as practitioner
Keywords: tolerance-cost-optimization; scrap rate; Latin-Hypercube-Sampling

Comparison of Different Sensitivity Analysis Methods in the Context of Dimensional Management - Heling, Björn; Oberleiter, Thomas; Schleich, Benjamin; Willner, Kai; Wartzack, Sandro (ASME 2017 International Mechanical Engineering Congress and Exposition, Volume 2: Advanced Manufacturing, 2017)
Although mass production parts look the same, every manufactured part is unique, at least on a closer inspection. The reason for this is that every manufactured part is inevitable subjected to different scattering influencing factors and variation in the manufacturing process, such as varying temperatures or tool wear. All these factors inevitably lead to parts, which deviate from their ideal shape. Products, which are built from these deviation-afflicted parts consequently show deviations from their ideal properties. To ensure that every single product nevertheless meets its technical requirements, it is necessary to specify the permitted deviations. Furthermore it is necessary to estimate the consequences of the permitted deviations, which is done via tolerance analysis. During this process the imperfect parts are assembled virtually and the effects of the geometric deviations can be calculated during a variation simulation. Since the tolerance analysis is to enable engineers to identify weak points in an early design stage it is important to know which contribution every single tolerance has on a certain quality-relevant characteristic, to restrict or increase the correct tolerances. In this paper two different approaches are shown and compared to represent the statistical behavior and the strongly connected sensitivity analyses. In particular a newly developed approach, which is based on fuzzy arithmetic, is compared to the established EFAST-method. The exemplary application of both methods and the comparison of the results are illustrated on a case stud

Comparison of maximum hip abductor torques from patient-specific multibody simulation models with isometric and isokinetic force measurements - Fleischmann, Christopher; Leher, Irina; Scherb, David; Kollerer, Marius; Miehling, Jörg; Wartzack, Sandro; Sesselmann, Stefan (Human Interaction & Emerging Technologies (IHIET 2023): Artificial Intelligence & Future Applications, 2023)
Muscuolskeletal simulations have become an important tool to simulate biomechanical properties. However, adaption of the models to patients or test persons is relevant in order to obtain realistic results (e.g. hip joint moments or muscle forces). It is particularly important to correctly reproduce the patient-specific maximum isometric muscle forces of the individual musculotendinous structures. The purpose of this work is to determine the extent to which gluteal muscle adaptation has an impact on the maximum hip joint moment during hip abduction.Based on MRI images volumes of the gluteal muscles were determined. These were used to calculate the muscles' maximum isometric force via the physiological cross-sectional area and the specific muscle tension. Since the values of the specific tension differ greatly in literature, several models were created. The models were investigated regarding their maximum hip joint moment and compared, first, to a marker-based scaled generic model and, second, to isokinetic and isometric force measurements using a dynamometer.It was shown that both, the models and the muscle strength measurements, show a maximum in the lower area of hip abduction and decrease sharply with increasing abduction. The models with a lower specific tension were much closer to the measured maximum hip torques. Higher values for the specific tension and the model without patient-specific information on the musculature were above the strength measurements. However, all models are clearly above the measurements with increasing abduction.It can be concluded that the gluteal muscles should be simulated with rather lower values of the specific tension.
Keywords: Biomechanics; Isometric Force; Isokinetic force; Muscle segmentation; patient-specific modelling

Compensating Deviations During Flexible Pin-type Moulding of Spatially Curved CFRP by Using 3D-Surface Detection - Lušić, Mario; Katona, Sebastian; Hornfeck, Rüdiger (Procedia CIRP, 2016)
Laminating carbon-fiber-reinforced plastic (CFRP) traditionally uses rigid moulds. This process means that customising CFRP components is expensive since the costs of each rigid mould are allocated fully to only one associated CFRP. Therefore, using form-flexible moulds is beneficial, because it would eliminate the conventional restriction that each CFRP geometry needs one single rigid mould. The costs of one flexible mould would be allocated to all produced CFRP components. Thus, the more CFRP laminated on this single form-flexible mould, the less the CFRP is affected by mould costs. Creating form-flexible moulds by using pin-type tooling results in a discrete pin accumulation. To achieve the required continuous laminating surface, an interpolation layer is placed on the pins. However, compared to conventional CFRP moulds, normally made by CNC-milling, pin-type tooling complicates accuracy achievement. This is due to the fact that the elastic, silicone-like interpolation layer as well as several tolerances or inaccuracies within the mould mechanics, as an assembly, accumulate into the range of millimeters. Instead of using more accurate pin-type moulds, which is associated with increasing costs, this paper introduces an approach to integrate 3D surface detection methods into the process of form-flexible moulding of spatially curved CFRP using pin-type tools, which maintains costs and increases accuracy. The developed control loop compensates deviations dynamically and results in accuracies in the same range as parts produced using CNC-milled rigid moulds.
Keywords: Quality Assurance; Form Flexible Moulding; Pin-Type Tooling; CFRP; 3D Surface Detection

Complexity-reduced Simulation of Hybrid Adhesive Joints - Witzgall, Christian; Kellermeyer, Markus; Wartzack, Sandro (Grazer Symposium Virtuelles Fahrzeug, 2016)

Compliant mechanisms with selective compliance - Hasse, Alexander; Campanile, Lucio Flavio (EMPA Activities, 2009)
Keywords: Compliant mechanisms; selective compliance

Compliant Morphing Wing - Previtali, Francesco; Bleischwitz, Robert; Hasse, Alexander; Campanile, Lucio Flavio; Ermanni, Paolo (22nd International Conference on Adaptive Structures and Technologies, 2011)
Morphing wings have a high potential for improving performance and for reducing fuel consumption of modern aircraft. Using the compliant rib designed by Hasse and Campanile as a starting point, a compliant morphing wing made of composite materials is designed. The performance of the compliant morphing wing in terms of three-dimensional structural behaviour, of two- and three-dimensional aerodynamic properties, are presented and discussed. Additionally, a new three-dimensional synthesis approach for belt-rib airfoils is introduced.
Keywords: Morphing; shape-adaptation; belt-rib; compliant mechanism; optimization.

Compliant morphing wing - recent developments - Campanile, Lucio Flavio; Hasse, Alexander; Previtali, Francesco; Thwapiah, Ghalib Y.; Ermanni, Paolo (21st International Conference on Adaptive Structures and Technologies, 2010)
The use of compliant structures has revealed itself as one of the key ideas for the realisation of morphing airfoils. In this paper, recent developments on this area at Empa are described. The first main topic treated in this work is the development of an innovative construction philosophy which conciliates compliant mechanisms with the principles of lightweight structures. This development points at airfoils which are essentially monolithic, with no moving parts, and which are designed for the three main requirements of deformability, high loads and low weight. The paper deals on optimisation-based design procedures for such class of airfoils. The optimal layout of the structure is found by imposing prescribed properties on the eigenvalues of the stiffness matrix. The resulting design is characterised by a so-called selective compliance, which conciliates good shape controllability with the advantages of a monolithic construction and of smooth deformation patterns. As is shown by the prototypic implementation of the results, such optimisation-based procedures are particularly advantageous in conjunction with generative manufacturing techniques like Selective Laser Sintering or Melting. The second focus of the work is on the exploitation of aeroelastic coupling effects, which is made particularly efficient by employing compliant airfoils with proper bending and/or torsion compliance. The paper presents the case of a forward-swept compliant wing operating in sub- and post-critical conditions. Amplification factors of more than four were experimentally observed on the aerodynamic lift for a flow dynamic pressure of 80% of the critical value. For higher values the amplification effect becomes even stronger. This makes the use of such airfoil feasible even with low-authority smart materials as actuators. The description of the above mentioned developments is illustrated by analytical, numerical and experimental results of laboratory tests and wind-tunnel measurements. © (2010) by the International Conference on Adaptive Structures and Technologies (ICAST).
Keywords: Belt-rib structures; Morphing wing; Shape-adaptation; Compliant mechanism

Compliant solutions for industrial products - Campanile, Lucio Flavio; Hasse, Alexander (EMPA Activities, 2007)
Compliant systems are a peculiar class of mechanical systems designed to produce controllable large deformations by exploiting structural flexibility. They can be seen as a blend between structures (elastically deformable, but only up to a limited extent) andmechanisms (large deformations, but produced by means of localized sliding elements like bearings and hinges and not by elastic deformations). In close collaboration with industrial partners Empa is investigating compliant solutions for products of several industrial sectors (e.g. surgery instrumentation, sport articles, eye glasses and prostheses).
Keywords: Compliant mechanism

Computational Geometry Reconstruction from 3D Topology Optimization Results: A New Parametric Approach by the Medial Axis - Mayer, Johannes; Wartzack, Sandro (Computer-Aided Design and Applications, 2023)
Topology Optimization (TO) is used to develop high strength, yet lightweight structural components. The geometry reconstruction from raw optimization results is a crucial task and especially challenging to do considering product development’s demand on parametrics. In this paper a new automated approach for computational reconstruction is presented that uses the Medial Axis for abstraction and inclusion of parametrics and features in the reconstruction. The presented method is both highly automated and at the same time offers optional geometry editing within the reconstruction itself. The steps of the method are (1) analysis of the TO result by the Voronoi computed Medial Axis Transform, (2) processing of the Medial Axis Transform into a decomposition, and (3) redesign thereon. Directly usable files of Computer-Aided Design (CAD) are generated. The concept is presented at real world case studies with focus on non-beam-like, structural component
Keywords: Topology Optimization; Computer-Aided Design; Computational Design; Geometry Reconstruction; Skeletonization; Medial Axis Transformation

Computation and Visualization of Patch Geometries for the Design of Carbon Fiber Reinforced Parts at Early Design Stages - Klein, Daniel; Scheler, Kaja; Wartzack, Sandro (Proceedings of the 24th CIRP Design Conference 2014, Milano, Italy, 2014)
The market for carbon fibers is forecast to experience a double-digit growth over the next years. The reason for this development can be found in the special characteristics of Carbon Fiber Reinforced Plastics (CFRP) like high stiffness and strength at very low weight which make this composite an ideal material for lightweight design. However, the design of parts made of CFRP is a tightrope walk between costs, mechanical characteristics and manufacturability for product developers. On the one hand, the mechanical properties are highly dependent on the ideal fiber orientation within the part and the unique material characteristics can only be exploited with a suitable fiber orientation, but on the other hand, the ideal fiber orientation is often not manufacturable or the required manufacturing technique is too expensive. Therefore, a novel algorithm to support product developers in finding a manufacturable fiber orientation or patch layout which is as close as possible to the ideal fiber orientation is introduced. This algorithm computes and highlights areas with constant fiber orientation (=cluster) based upon the ideal fiber alignment from the CAIO method. With the help of the visualization of the clusters, product developers can be supported in the decision for the best patch placement and geometry as well as in choosing the best manufacturing technique. It is important to point out that the algorithm is intended for endless fiber reinforced parts only.
UnivIS-Import:2015-04-16:Pub.2014.tech.FT.FT-KLMEFK.comput
Keywords: Early design stages; Endless fibre reinforced composites; Lightweight design

Computer Aided Ergonomics: Evaluation Study of a Interaction Model for Digital Human Models - Wolf, Alexander; Fackler, Konrad; Reulbach, Magnus; Wartzack, Sandro; Miehling, Jörg (Proceedings of the Design Society, 2022)
In user-centred design, digital human models hold the potential for proactive evaluations of ergonomics or discomfort in terms of a computer aided ergonomics tool. Therefore, models predicting human interaction behaviour, are necessary. In this contribution we present such a model as well as its initial evaluation. The evaluation is performed by applying the interaction model to a specific use case, conducting a comparison with an empirical subject study. The evaluation shows that similar and realistic human behaviour was predicted, which was consistent in terms of whole-body strai
Keywords: user-centred design; interaction design; digital human models; evaluation; computer-aided ergonomics

Computer Aided Ergonomics Through Parametric Biomechanical Simulation - Miehling, Jörg; Schuhhardt, Jürgen; Paulus-Rohmer, Florian; Wartzack, Sandro (ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Volume 1B: 35th Computers and Information in Engineering Conference, 2015)
Computer aided ergonomics and particularly biomechanical simulations hold high potential for the implementation of the virtual product development paradigm in the field of human-centric design. Unfortunately, the relation between efforts to be invested to the insights gained by musculoskeletal simulations is still not sufficient for a widespread industrial application. This contribution shows how parametric biomechanical simulations can be used to gain specific indications on how interaction points of human-centric products are to be designed to meet the competencies of a given target user. This is demonstrated using cycling and rowing as two exemplary activities involving the entire human body. These activities are empirically well studied and electromyographic as well as force measurements are available. The comparison of the biomechanical simulations to the real-world scenario permits the validation of the proposed parametric approach as well as the applied models. This is a prerequisite for its application along the product engineering process.
Keywords: Computer-aided engineering; Simulation; Biomechanics; Ergonomics

Computer Aided Internal Optimisation (CAIO) method for fibre trajectory optimisation: A deep dive to enhance applicability - Völkl, Harald; Franz, Michael; Klein, Daniel; Wartzack, Sandro (Design Science, 2020)
The computer aided internal optimisation (CAIO) method produces an optimised fibre layout for parts made from fibre-reinforced plastics (FRP), starting from an initial shell geometry and a given load case. Its main principle is iterative reduction of shear stresses by aligning fibre main axes with principal normal stress trajectories. Previous contributions, ranging from CAIO’s introduction over testing to extensions towards multi-layer FRP laminates, highlighted its lightweight design potential. For its application to laminate design approaches, alterations have been proposed; however, questions remain open. These questions include which convergence criteria to use, how to handle ambiguous principle normal stress trajectories, influence of using multi-layer CAIO optimisation instead of the initial single-layer CAIO and how dire consequences of slightly deviating fibre orientations from the optimised trajectories are. These challenges are discussed in depth and guidelines are given. This paper is an enhanced version of a distinguished contribution at the first symposium ‘Lightweight Design in Product Development’, Zurich (June 14–15, 2018
Keywords: lightweight design; fibre trajectory optimisation; CAIO; fibre-reinforced plastics

Computer Aided Internal Optimization (CAIO) method for fiber trajectory optimization: enhancing applicability - Völkl, Harald; Franz, Michael; Wartzack, Sandro (1st Symposium for Lightweight Design and Product Development, 2018)
The bio-inspired Computer Aided Internal Optimization (CAIO) method optimizes fiber orientation of composite structures by minimizing shear stresses. Fiber directions are iteratively aligned with maximum principal normal stress trajectories (MPNST). Its effectiveness was exemplarily shown by Reuschel and Mattheck (1999) using a tension-loaded plate with two holes, doubling the strength of a specimen compared to an unidirectional design. Klein (2017) uses this method in a holistic approach to composite design – and points out, to find its way into practice more, the iterative method still leaves room for further research. This is especially the case in areas of non-unique MPNST. The extended abstract scrutinizes the behavior of the method in these areas and evaluates possible solutions<br

Computer-aided tolerance specification of preliminary designs based on variation analysis - Götz, Stefan; Lechner, Timo; Schleich, Benjamin (Procedia CIRP, 2022)
A proper tolerance specification ensures assemblability as well as functionality of products and considers associated manufacturing costs. Therefore, numerous, mostly rule-based computer-aided approaches aim to support this challenging task. However, the aspect of functional performance is often considered only indirectly or generically, e.g. without taking into account existing dimension relations, so that iterative manual adjustments are necessary. In order to overcome this shortcoming, a new method is presented, which automatically generates specific tolerance specification proposals on the basis of degree-of-freedom analyses of the contact faces contributing to a defined assembly function. Thus, it enables a reliable, function-oriented tolerance specification of preliminary designs already in early product development stages. The novel approach is prototypically integrated into a CAD system and demonstrated by means of a crank drive mechanism.<br

Computing solution spaces for gear box design - Ziegler, Klara; Demir, Kutay; Luft, Thomas; Mucks, Thomas; Fürst, Marius; Otto, Michael; Stahl, Karsten; Vogel-Heuser, Birgit; Zimmermann, Markus (Proceedings of the Design Society, 2024)
The design of gear boxes is a complex challenge characterized by conflicting requirements and seemingly circular dependencies. Existing tools support engineers but focus on a single predefined design, often leading to costly iterative processes and non-optimal solutions. Solution Space Engineering (SSE) alleviates this by generating multiple designs represented by solution spaces. For this, a particular model structure is needed, and thus restructuring existing models, e.g., from industry standards. The application of solution spaces to a two-stage gear box is presented.
CRIS-Team Scopus Importer:2024-05-31
Keywords: design process; design tools; gear box design; product development

Concept and application of automatic part-recognition with artificial neural networks for FE simulations - Sprügel, Tobias; Wartzack, Sandro (Proceedings of the 20th International Conference on Engineering Design (ICED15), 2015)
Currently available finite element software is consequently getting more and more user-friendly, and simulation knowledge must be expanded to a growing pool of new and less-experienced users; for example designers. These users need to be assisted when performing simulation tasks. A promising way is to check the FE results for plausibility, but therefore, it is essential to know what kind of parts should be simulated and checked for plausibility. This paper presents a concept for the automatic recognition of standard parts within the FE software, using a predefined Artificial Neural Network (ANN). An existing approach is extended to deal with the issues of arbitrarily oriented parts in CAD (computer-aided design) assemblies of differing size in 3D space. Hence a Principal Component Analysis (PCA), and a spherical detector surface for FE nodes in spherical coordinates is used to gain input parameters for an ANN. In the paper, the concept and an application for certain standard components are demonstrated.
UnivIS-Import:2015-10-26:Pub.2015.tech.FT.FT-KLMEFK.concep
Keywords: Simulation; Design informatics; Artificial Neural Networks (ANN); part-recognition; FE simulation

Concept and implementation of a central knowledge framework for simulation knowledge - Kestel, Philipp; Sprügel, Tobias; Katona, Sebastian; Lehnhäuser, Thomas; Wartzack, Sandro (NAFEMS European Conference: Simulation Process and Data Management, 2015)
Due to increasing product- and process-requirements and shorter development periods the usage of numerical simulations has become an essential part of the product development process. This has led to expose simulation to not only the CAE experts but also to less experienced users such as designers. However, such users typically do not have the expertise to perform simulations from the ground up and need appropriate help systems.   Therefore, the aim of the Bavarian Research Cooperation FORPRO² for “Efficient Product and Process Development by Knowledge based Simulation” is to increase the efficiency of virtual product and process development. This is achieved by creating a simulation environment that allows corresponding users to automatically benefit from expert practices and knowledge. As a result, non-expert users can produce reliable results for virtually optimizing design parameters. This will allow shifting work load from the simulation engineer to the designer. As a consequence, the simulation process will become more agile and quick without compromising on quality of the simulation and the final product.   The goal of the simulation environment is to provide the necessary situational simulation knowledge as a function of decisive factors such as the phase in the development process, the manufacturing processes employed, and the company's individual circumstances. Considering such a wide range of factors, results in several challenges in the development of the simulation framework. Some of the challenges are associated with (manual or automatic) extraction processes of simulation knowledge from existing sources and the publication of the knowledge to the end user in an adequate manner.   The presentation will demonstrate the implementation of the central knowledge environment within the framework of a commercial SPDM system. Special emphasize will be laid on presenting an automatic acquisition of simulation knowledge from validated simulation reports by means of KDD-processes (Knowledge Discovery in Databases). The overall approach is demonstrated by considering the use case of performing a numerical FE simulation with real life geometry (including deviations caused by the manufacturing process) instead of ideal geometry from the CAD system (see image below for a the conceptual workflow for this use case).

Concept development for innovative products - a challenge for engineering design education - Luft, Thomas; Schleich, Benjamin; Wartzack, Sandro (DS 75-8: Proceedings of the 19th International Conference on Engineering Design (ICED13), 2013)
The complexity of new products steadily increases and therefore integrated engineering designers have to be skilled in various fields in order to develop innovative and successful products. This trend has to be considered in university education. Therefore, a new educational concept called âConcept Development for Innovative Productsâ (CIP) is proposed. In this subject the students are confronted with a vague task and are asked to develop and to present concepts for innovative products in teams of five. In this regard, CIP is a combination of three forms of teaching, which are presenting the working progress, discussing and lectures on demand. During mandatory working meetings the students have to present the project status to the supervisors and discuss the next steps with them. Furthermore, they can ask for lectures on specific engineering design methods which are presented using a comprehensive method catalog. The student feedback for CIP in the first semester was excellent and it is a very good enhancement for the curriculum. Consequently, the students are well prepared for a harmonic transition from university to their professional careers.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.concep_8
Keywords: Design education; conceptual design; design methods; teamwork

Concept for Improving the Traceability of Design Automation through Reinforcement Learning - Utz, Yannick; Götz, Stefan; Wartzack, Sandro (Tagungsband zum Stuttgarter Symposium für Produktentwicklung SSP 2025, 2025)
Reinforcement learning (RL) methods can be used for the automation of design adaptations due to their inherent iterative nature. However, they present difficulties with regard to the interpretability of the results. One reason for this is that RL methods are integrated into the product development process as black boxes. As a result, the use of these methods in safety-critical areas such as mechanical design is only possible to a limited extent due to the lack of traceability of the design decisions made by the algorithm. In order to increase the usability of RL-based tools supporting the product developers, the interpretability of the RL-based results must be improved. Therefore, this paper proposes a concept for increasing the traceability of RL-based tools for the automation of design adaptations. Traceability is to be improved by imitating the decision-making process of experts. To this end, the concept is presented using a design adaptation of fibre-plastic composite (FRP) components.<br
Keywords: Reinforcement Learning; Design Automation; Traceability; Decision Making

Concept for the Architecture of A Self-Learning Engineering Assistance System - Röhner, Sebastian; Gruber, Georg (Proceedings of Norddesign 2010: International Conference on Methods and Tools for Product and Production development, 2010)
Considerable efforts have been taken in the past decades to integrate design and manufacturing knowledge into the product development process. A common approach is to offer designers the support of knowledge based systems, expert systems or assistance systems. There are several methodologies of these systems which differ in representing and reasoning of knowledge. Keeping their knowledge base up to date is a crucial, yet demanding issue. Currently most means of knowledge acquisition are labour-intensive for knowledge engineers and domain experts. Thus, the knowledge acquisition process is often the bottleneck, and automatic knowledge acquisition from databases is a promising approach to overcome it. In this paper a concept for the architecture of a self-learning engineering assistance system is presented, that uses data mining methods for the acquisition, updating and reasoning of knowledge.
UnivIS-Import:2015-04-16:Pub.2010.tech.FT.FT-KLMEFK.concep
Keywords: Artificial intelligence; Assistance system; Data mining

Concept for tolerance design in early design stages based on skeleton models - Ziegler, Philipp; Wartzack, Sandro (Proceedings of the 19th International Conference on Engineering Design, 2013)
A noticeable trend in mechanical industry is that the product lifecycle and within the product development phase shortens. One consequence is the necessity to perform product-analyses already in early design stages, even if the geometry of the product is only sketchy defined by skeleton models. For product functionality the dimensional and geometric variations of the product components play an important role, which are analyzed and limited by tolerancing. The lack of geometric information in the early design phase is challenging for tolerance analysis, but also offers chances by more flexibility of the product developer in changing the products geometry. Therefore, this paper presents the concept to perform tolerance design based on skeleton models.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.concep
Keywords: Computational design synthesis; Contributor analysis; Early design phases; Tolerance design

Concept of a Modular and System Model Driven Digital Twin for Engineering Education - Wilking, Fabian; Behringer, Marc; Fett, Michel; Götz, Stefan; Kirchner, Eckhard; Wartzack, Sandro (IEEE International Conference on System of Systems Engineering (SoSE), 2023)
Driven by the opportunities for condition monitoring and new business models, Digital Twins have become a popular topic within research and industrial application over the last years. Therefore, universities must integrate the development of Digital Twins into their educational program to enable future engineers to overcome the challenges concomitant with Digital Twins. While a theoretical basis for Digital Twins is crucial e.g., hardware-software integration, Internet of Things (IoT) or simulation models, a practical combination of these heterogeneous components is also necessary to introduce the Digital Twin as a whole concept. With Model-Based Systems Engineering (MBSE) an approach was introduced to grasp complexity by using system models e.g., through SysML diagrams. Digital Twins are an example for advanced systems shaped by high complexity. The usage of system models is therefore likely. With this contribution, a concept is presented to combine system models and Digital Twins to create a prototype for academic education and the conduction of student projects.<br

Conceptualization and Elaboration of a Teaching Unit on Digital Twins in Geometrical Variations Management - Schleich, Benjamin; Roth, Martin; Schächtl, Paul (Procedia CIRP, 2022)
Driven by the steadily increasing digitization of design and manufacturing, digital twins, which describe the tight connection of models from design with data streams from manufacturing and product operation, are becoming more and more important. Particularly in geometrical variations management, digital twins can be used beneficially, for example, to identify joining partners that fit together ideally despite geometrical deviations, thereby reducing manufacturing costs and increasing product quality. Motivated by the increasing importance of these approaches with a simultaneous lack of training offers for this, a teaching unit was developed, which aims at students acquiring competencies for the independent development of a digital twin and its exemplary use in geometrical variations management. The paper describes the conceptualization and elaboration of this teaching unit on digital twins in geometrical variations management and carves out opportunities for its further improvement.<br

Conceptual Model for (Semi-) Automated Derivation of Evaluation Criteria in Requirements Modelling - Horber, Dennis; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the Design Society, 2020)
Requirements act as a limitation of the solution space, which represents the stakeholders’ needs and guides the whole product development process. Therefore, forgotten requirements can lead to wrong decisions when using them as a basis for decision-making. This contribution introduces a novel approach to link the requirement and evaluation criteria models to address this problem. For setting up those criteria consistently, the requirements are classified using natural language processing and derived by a ruleset based on a developed mapping between requirement classes and criteria type
Keywords: requirements management; decision making; design evaluation; natural language processing

Concurrent Machine and Batch Size Selection in Sampling-based 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.
Keywords: Least-cost tolerance allocation; Tolerance-cost optimization; Machine selection; Batch size; Process planning

Consideration and impact assessment of measurement uncertainty in the context of tolerance analysis - Heling, Björn; Müller, Andreas; Schleich, Benjamin; Hausotte, Tino; Wartzack, Sandro (Proceedings of the ASME 2019 International Mechanical Engineering Congress and Exposition, 2019)

Consideration of anisotropic material properties in mechanical design within early design phases - Gruber, Georg; Klein, Daniel; Ziegler, Philipp; Wartzack, Sandro (NordDesign 2012 - Proceedings of the 9th NordDesign Conference, 2012)
To achieve the goal of simulating the structural behavior of parts made of short fiber reinforced polymers with satisfactory accuracy and justifiable modeling effort, a new approach adapted to the needs of the early design steps was developed at the Chair of Engineering Design (KTmfk). Hereby, the various effects of material behavior are modeled by overlapping two different material models in one finite element definition. The anisotropic material properties are determined by an injection molding simulation. The complexity of the resulting fiber distribution is reduced to just three values per finite element. The paper's focus is the introduction of an automated method supporting the determination of the numerical material parameter and a new tensor based method enabling the averaging of the complex orientation state. The benefits of the new methods and a validation are presented.
CRIS-Team Scopus Importer:2020-04-28
Keywords: Early design steps; Fiber reinforced polymers; Lightweight design; Simulation

Consideration of Anisotropic Material Properties in Mechanical Design within Early Design Steps - Gruber, Georg; Klein, Daniel; Ziegler, Philipp; Wartzack, Sandro (Proceedings of the 9th Norddesign, 2012)
UnivIS-Import:2015-04-16:Pub.2012.tech.FT.FT-KLMEFK.consid_2

Consideration of operational wear in tolerance analysis for process-oriented tolerancing - Bode, Christoph; Schleich, Benjamin; Wartzack, Sandro (Procedia CIRP, 2022)
Besides manufacturing-induced part deviations, operational wear in persistent moving assemblies leads to time-dependent deviations of part geometries and the functionality of the mechanism. This article presents an approach based on the Archard wear model to predict the lifetime functionality of an assembly by carrying out a tolerance analysis, considering both, time-dependent variations in wear activity due to volume loss and the impact of process-induced geometrical variation on the wear. The novelty of this approach lies in the consideration of time-varying operational wear effects in tolerance analysis and non-conformance rate estimation. To prove its applicability, the approach is applied to a one-way-clutch.<br
CRIS-Team Scopus Importer:2024-12-16
Keywords: Tolerance analysis; Operational wear; Non-conformance rates

Consideration of Orientation Properties of Short Fiber Reinforced Polymers within Early Design Steps - Gruber, Georg; Haimerl, Andreas; Wartzack, Sandro (12th International LS-DYNA® Users Conference, 2012)
UnivIS-Import:2015-04-16:Pub.2012.tech.FT.FT-KLMEFK.consid

Consideration of uncertainties in the product-oriented development process - Reitmeier, Jochen; Luft, Thomas; Wartzack, Sandro; Paetzold, Kristin (Modelling and Management of Engineering Processes, 2015)
Product developers have to develop modern products with increasing functionality and complexity in order to achieve the required functionality or property profile of products. Due to the multiple dependencies of defined characteristics and properties it is not always possible for developers to detect causes reliably, to identify possible alternatives and to analyze and evaluate their consequences completely. Hence, mainly the effects are combated or stemmed in the context of improvements (= iterations), but their causes are not eliminated. Therefore, the overall objective of the authors is to develop a procedure model for iteration and product maturity management as well as for an appropriate planning of virtual validations in the property-based product development. In this contribution the handling of uncertainties within the development process is focussed. This is shown by using the example of a wheel hub and thereby can be demonstrated that it is not only possible to optimize the development process but also to improve the product itself.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.consid
Keywords: Process optimization; process management; uncertainty; matrix-based product description; virtual property validation

Considering Emotional impressions in Product Design: Quality of Life Theory and its impact on Design Strategy - Kett, Susan; Wartzack, Sandro (Proceedings of the DESIGN 2016 14th International Design Conference, 2016)
In this paper, the necessity of emotional considerations in the context of Universal Design is treated. To work out an alternative approach how to integrate emotional aspects in product design processes, we look at quality of life models to locate emotional design in Universal Design research. Based on identified challenges such as complexity, interdisciplinarity, vagueness or subjectivity we present a way to consider emotional impressions by integrating resources from other disciplines. Hence we introduce ACADE - an Application for Computer Aided Design of Emotional impressions.
Keywords: universal design; emotions in design; user centered design; engineering design tools; data analysis

Considering Emotional Impressions in Product Design: Taking on the Challenges Ahead - Kett, Susan; Wartzack, Sandro (Entwerfen Entwickeln Erleben 2016 - Beiträge zum Industrial Design, 2016)
There is a stronger focus on emotional aspects affecting users' product selection as ever before. Recent User Centred Design (UCD) approaches already take up this fact, but still this is at the very beginning regarding UCD implementation. As on addressing emotional aspects in particular, the big challenge lies in the management of their low grade of concretisation and intense complexity. From other disciplines such as marketing strategy, psychology or sociology, we know instruments that help to describe this fuzzy theme. But still, its discrete integration into product development processes and high complexity remains as one main issue. In this paper, the challenges in design for emotions in the context of UCD are firstly examined to understand possible starting points. We give potential reasons for the insufficiency of current approaches, answering the question why there is no adequate tool for their consideration so far. Therefore, we summarize some of the challenges that exist both in UCD itself and its relevant enhancement for emotional consideration. We extract these findings during our studies reviewing several relevant surveys and research literature. Often, it is hard to make decisions only based on implicit information. Even though the designer can make good decisions based on his own well trained emotional perception ability, he might not be able to do so for whole target groups. Moreover, the communication between different parties in the interdisciplinary field needs improvement. In the field of UCD, it is obligatory both to manage the future users' and the developer teams' heterogeneity. So a reliable objectification of subjective information in an interdisciplinary field becomes necessary. Based on the findings on the present knowledge, an approach called ACADE - Application for Computer Aided Design of Emotional impressions - is presented. ACADE is a tool that systematically processes and links subjective and implicit information to objective, measurable data that can be used as basis for high-quality decision making in product design. To get an overview of the different elements in its architecture, they will be carefully explained. Giving a firm example, we show the general workflow and linkages. Thus we illustrate the potential of ACADE for future research in emotional design by addressing the aforementioned identified UCD problems. ACADE supports strategic product design decisions. Its application in product development environments can be extremely extended to support decision making in product development throughout the whole process. It enables the transparency and the traceability of decisions in a highly implicit domain. Barriers in communication caused by the interdisciplinary of decision-makers may be reduced. Moreover, it forces the product developer to look at his product to be designed through the emotional profile of the user. With ACADE, an important step forward to a holistic, interdisciplinary UCD is given.
Keywords: User Centered Design; Emotional Design; Designing for User Attitudes; Product Design; ACADE

Considering Users’ Emotions in Product Development Processes and the Need to Design for Attitudes - Kett, Susan; Wartzack, Sandro (Emotional Engineering, 2017)
In recent times there has been an increasing need to consider subjective values in user-centred design for technical products. Therefore, the relations between perceived value to the user and different product design elements have been investigated in former research. Although there are many approaches that address this issue, little advice has been given so far on how to use this knowledge truly to consider the users’ preference. Even if we know that a product appears to be “sporty” to the user, and even if we know how to design the product to look “sporty”, we still do not know “how sporty” he might like it to be. Moreover, studies have revealed that there are huge differences in user groups that cannot easily be detected using only common segmentation criteria like age, family situation or income. Depending on their personal attitudes and values, individuals’ preferences for products may differ widely despite the objective user characteristics looking similar. Therefore, an approach called the ACADE is presented, which combines interdisciplinary knowledge of users’ long-term evaluation system and preference choice.
Keywords: Emotional Engineering; User-centered Design; Attitudes; Subjective Quality; Kansei Engineering

Consistent digitalization of engineering design – an ontology-based approach - Kügler, Patricia; Schleich, Benjamin; Wartzack, Sandro (Norddesign, 2018)
Digitalization and Industry 4.0 are currently trend words in companies and research, which express the striving for digitalized manufacturing environments and autonomous manufacturing processes enabled by cyber-physical production systems. But where do we stand in product development? Modern virtual product development tools and processes allow the definition of product geometry and shape in fully three-dimensional computer-aided design environments. Additionally, even semantic information, for instance about the subsequent manufacturing, can be included employing feature-technology. Moreover, virtual testing of these three-dimensional product models can be performed using sophisticated computer-aided engineering and simulation tools leading to digitally supplied output data. However, CAD and simulation tools mainly support later design activities, while there is a lack of computer support in early design stages. This lack of digitalization in such early design stages eliminates the possibility of retracing the customer requirements in the product at late design activities. In consequence, the decisions made during the design process are hardly comprehensible and therefore existing product knowledge is difficult to reuse. This contribution shows the needs for a consistent digitalization of engineering design with focus on the early stages. This consistent digitalization refers to a representation and linkage of work results in design processes, which allows inference and reasoning between them. Thus, reusing of product knowledge becomes more comprehensible. Moreover, this contribution presents an ontology-based approach for this consistent digitalization, which particularly enables product developers to link early design stages to late design stages and to establish relations between customer requirements and the finished product. The approach thus supports the efficient reuse of relevant design knowledge employing an ontology. Besides this, the paper discusses the general advantages of ontologies for transparently storing and efficiently providing product knowledge. With the novel ontology-based approach proposed in this contribution, the reuse of finished product development processes becomes more efficient and transparent.<br
Keywords: Ontologies; Knowledge-based Engineering; Requirements Engineering; Information Integration

Contact and Mobility Simulation for Mechanical Assemblies Based on Skin Model Shapes - Schleich, Benjamin; Anwer, Nabil; Mathieu, Luc; Wartzack, Sandro (Journal of Computing and Information Science in Engineering, 2015)
Assembly modeling as one of the most important steps in the product development activity relies more and more on the extensive use of computer-aided design (cad) systems. The modeling of geometric interfaces between the components of the assembly is of central importance in the simulation of mechanical assemblies. Over the past decades, many researchers have devoted their efforts to establish theories and systems covering assembly modeling. Although the product form or shape has been extensively investigated considering the nominal cad geometry, inevitable limitations can be reported. Computer aided tolerancing (CAT) systems provide simulation tools for modeling the effects of tolerances on the assembly but still lack of form deviation considerations. The skin model concept which stemmed from the theoretical foundations of geometrical product specification and verification (GPS) has been developed to enrich the nominal geometry considering realistic physical shapes. However, the digital representation of the skin model has been investigated only recently. This paper presents a novel approach for a skin model based simulation of contact and mobility for assemblies. Three important issues are addressed: the geometric modeling of the contact, the contact quality evaluation, and the motion analysis. The main contribution to CAT can be found in the analysis of the effects of geometric form deviations on the assembly and motion behavior of solid mechanics, which comprises models for the assembly simulation, for the contact quality evaluation, and for the motion analysis. A case study is presented to illustrate the proposed approaches.

Continuous simulation of variations during the design of endless fiber reinforced composite structure assemblies - Freitag, Stephan; Götz, Stefan; Wartzack, Sandro (Proceedings of the 34th Symposium Design for X (DFX2023), 2023)

Contributing Components of Metabolic Energy Models to Metabolic Cost Estimations in Gait - Gambietz, Markus; Nitschke, Marlies; Miehling, Jörg; Koelewijn, Anne (IEEE Transactions on Biomedical Engineering, 2023)
Objective: As metabolic cost is a primary factor influencing humans' gait, we want to deepen our understanding of metabolic energy expenditure models. Therefore, this paper identifies the parameters and input variables, such as muscle or joint states, that contribute to accurate metabolic cost estimations. Methods: We explored the parameters of four metabolic energy expenditure models in a Monte Carlo sensitivity analysis. Then, we analysed the model parameters by their calculated sensitivity indices, physiological context, and the resulting metabolic rates during the gait cycle. The parameter combination with the highest accuracy in the Monte Carlo simulations represented a quasi-optimized model. In the second step, we investigated the importance of input parameters and variables by analysing the accuracy of neural networks trained with different input features. Results: Power-related parameters were most influential in the sensitivity analysis and the neural network-based feature selection. We observed that the quasi-optimized models produced negative metabolic rates, contradicting muscle physiology. Neural network-based models showed promising abilities but have been unable to match the accuracy of traditional metabolic energy expenditure models. Conclusion: We showed that power-related metabolic energy expenditure model parameters and inputs are most influential during gait. Furthermore, our results suggest that neural network-based metabolic energy expenditure models are viable. However, bigger datasets are required to achieve better accuracy. Significance: As there is a need for more accurate metabolic energy expenditure models, we explored which musculoskeletal parameters are essential when developing a model to estimate metabolic energy.<br
Keywords: Muscles; Costs; Computational modeling; Biological system modeling; Analytical models; Estimation; Biomedical measurement; Biomechanics; Deep Learning; Gait; Metabolic Cost; Sensitivity Analysis

Correlating Wine Astringency with Physical Measures – Current Knowledge and Future Directions - Rosenkranz, Andreas; Marian, Max; Shah, Raj; Gashi, Blerim; Zhang, Stanley; Bordeu, Edmundo; Brossard, Natalia (Advances in Colloid and Interface Science, 2021)
Oral tribology receives growing attention in the field of food sciences as it offers great opportunities to establish correlations between physical parameters, such as the coefficient of friction, and sensory effects when interacting with components of the human mouth. One important aspect covers the astringency produced by wine, which can be described as the sensation of dryness and puckering in the mouth, specifically occurring between the tongue and the palate after swallowing. Therefore, this article aims at shedding some light on recent trends to correlate physical measures, such as the coefficient of friction derived by oral tribology, with prevailing theories on underlying physiological causes for sensory perception of wines. Some successful cases reported the potential of correlating wine astringency perception with the coefficient of friction in tribological experiments. Our critical assessment demonstrates that the findings are still contradictory, which urgently asks for more systematic studies. Therefore, we summarize the current challenges and hypothesize on future research directions with a particular emphasis on the comparability, reproducibility and transferability of studies using different experimental test-rigs and procedures.<br
Keywords: Oral lubrication; Wine astringency; Tribology testing; Perception-COF correlation; Tannin-protein interaction

Co-Simulationsmodell zur nutzerzentrierten Entwicklung von Unterstützungssystemen: Am Beispiel von Tätigkeiten in und über Kopfhöhe mit einem Schulter-Exoskelett und einem Akkuschrauber - Yao, Zhejun; Molz, Carla; Sänger, Johannes; Miehling, Jörg; Germann, René; Wartzack, Sandro; Matthiesen, Sven; Weidner, Robert (Zeitschrift für wirtschaftlichen Fabrikbetrieb, 2021)
Unterstützungssysteme zeichnen sich durch eine erhöhte Mensch- Maschine-Interaktion aus. Diese Interaktion und ihre Auswirkungen haben große Bedeutung für die Entwicklung und Anwendung von Unterstützungssystemen und führen zu einer besonderen Herausforderung bei der Simulation entsprechender Systeme. Um diesen gerecht zu werden, wird ein Co-Simulationsmodell von Menschen, Exoskelett und Power-Tool entwickelt. Derartige Co-Simulationsmodelle ermöglichen bereits in der frühen Phase der Entwicklung der Unterstützungssysteme eine digitale Integration des Anwenders.<br
Keywords: Mensch-Maschine-Interaktion; Unterstützungssysteme; Produktentwicklung; Co-Simulation; Muskuloskelettales Menschmodell; Exoskelett und Power-Tool-Modelle; Biomechanik

Cost Optimality in Testing and Rejuvenation - Grottke, Michael; Schleich, Benjamin (2012 IEEE 23rd International Symposium on Software Reliability Engineering Workshops (ISSREW), 2012)
In this paper, we extend models for the test phase and the operational phase with cost aspects, to explore cost optimality in testing and rejuvenating software systems that can age. For example, we find that under limited resources it may be advisable not to focus on the removal of agingrelated bugs in the test phase; rather, the adverse affects of such bugs should primarily be prevented via software rejuvenation during operations. Our model-based analysis thus helps give a further theoretical foundation for the importance of software rejuvenation. © 2012 IEEE.
UnivIS-Import:2015-04-16:Pub.2012.tech.FT.FT-KLMEFK.costop
Keywords: Appraisal costs; External/internal failure costs; Quality costs; Rejuvenation rate; Test duration

Coupling Sampling-Based Tolerance-Cost Optimization and Selective Assembly – An Integrated Approach for Optimal Tolerance Allocation - Roth, Martin; Seitz, Markus Johannes; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the ASME 2022 International Mechanical Engineering Congress and Exposition (IMECE2022), 2023)
Optimization has gained increased attention in product development and is nowadays profitably used to solve complex design problems. In tolerance design, tolerance-cost optimization is a systematic and efficient approach to allocate part tolerance values in a cost-optimal way. The usage of sampling-based tolerance analysis techniques thereby enables the consideration of machine-specific part tolerance distributions as well as individual batch sizes and thus facilitates a concurrent allocation of tolerances and machines. With the aim to further exploit its potential by embedding assembly aspects, this article presents a novel approach combining tolerance-cost optimization and optimal selective assembly. Based on an initial introduction of its general idea, a global optimization problem is defined to simultaneously identify the best combination of tolerance values, machines with their batch sizes and sorting orders of the individual batches. Subsequently, its solution using metaheuristic optimization algorithms and mixed-integer variables is presented. The theoretical findings are finally confirmed by its exemplary application to a use case indicating that it can reveal hidden cost improvement potentials in tolerance desig
Keywords: tolerance-cost optimization; tolerance allocation; selective assembly; mixed-integer optimization; Monte Carlo sampling

Crashgerechter Leichtbau - Wartzack, Sandro; Gruber, Georg (Konstruktion, 2014)
UnivIS-Import:2015-03-09:Pub.2014.tech.FT.FT-KLMEFK.crashg

Crashsimulation kurzfaserverstärkter Kunststoffbauteile - Ein Ansatz für frühe Entwicklungsphasen - Gruber, Georg; Wartzack, Sandro (Kunststoffe + SIMULATION, 2012)
UnivIS-Import:2015-04-16:Pub.2012.tech.FT.FT-KLMEFK.crashs

Crash simulation of mechanically fatigued short-fibre reinforced thermoplastics: anisotropic failure considering previous damage - Witzgall, Christian; Wartzack, Sandro (VDI-Berichte, 2022)

Creating Sustainable Products - Ries, Lena; Wartzack, Sandro; Zipse, Oliver (Road to Net Zero, 2023)
On the Road to Net Zero, products must not only become CO2-neutral in the consumption phase, but the environmental impact needs to be mitigated from the extraction of the raw materials to their end-of-life disposal. The consideration of the entire life cycle—cradle to cradle—as well as rising consumer demand for sustainable products—requires a new paradigm in product design: Design for circularity. Circular design focuses on developing design strategies that enable circularity, such as material selection, design for disassembly, product lifetime extension strategies, and the design of closed-loop systems. Thus, the first section after the introduction of this chapter (Sect. 5.2) provides an overview of the research field of design for circularity. After reviewing the concept of the circular economy (CE), different frameworks for operationalizing the CE are outlined. Based on this review and discussion, we derive three implications for circular design: a change in product design, a change in service design, and a change in user behavior. Finally, we address the implementation challenges that manufacturing companies face when transitioning to a CE. In the subsequent expert discussion (Sect. 5.3) between Oliver Zipse and Prof.-Ing. Sandro Wartzack, these issues are reflected upon from a practitioner’s perspective. In the final section of this chapter (Sect. 5.4), future avenues of research are presented, and the challenges and opportunities of circular design strategies are discussed.<br
Keywords: Design for circularity; Circular economy; R-strategies; Product life cycle; Product service systems

Cross-Skates mit Elektroantrieb und hybridem Fahrmodus - Wartzack, Sandro; Miehling, Jörg; Kramer, Vincent (WiGeP News, 2023)

Current Trends and Applications of Machine Learning in Tribology—A Review - Marian, Max; Tremmel, Stephan (Lubricants, 2021)
Machine learning (ML) and artificial intelligence (AI) are rising stars in many scientific disciplines and industries, and high hopes are being pinned upon them. Likewise, ML and AI approaches have also found their way into tribology, where they can support sorting through the complexity of patterns and identifying trends within the multiple interacting features and processes. Published research extends across many fields of tribology from composite materials and drive technology to manufacturing, surface engineering, and lubricants. Accordingly, the intended usages and numerical algorithms are manifold, ranging from artificial neural networks (ANN), decision trees over random forest and rule-based learners to support vector machines. Therefore, this review is aimed to introduce and discuss the current trends and applications of ML and AI in tribology. Thus, researchers and R&D engineers shall be inspired and supported in the identification and selection of suitable and promising ML approaches and strategies.<br
Keywords: Tribology; machine learning; artificial intelligence; triboinformatics; databases; data mining; meta-modeling; artificial neural networks; monitoring; analysis; prediction; optimization

Das FEA-Assistenzsystem - Analyseteil FEdelM - Sprügel, Tobias; Wartzack, Sandro (Beiträge zur virtuellen Produktentwicklung und Konstruktionstechnik, 2016)
Die simulative Absicherung von Produkten in den frühen Phasen der Produktentwicklung wird immer wichtiger, um den Anforderungen nach steigender Effizienz gerecht zu werden. Da das Angebot an erfahrenen Berechnungsingenieuren mit langjähriger Berufserfahrung begrenzt ist gilt es weniger erfahrene Simulationsanwender bei der Durchführung von aussagekräftigen Finite-Elemente-Simulationen zu unterstützen. Die Autoren stellen im Rahmen des Beitrags das Konzept des Analyseteils FEdelM eines FEA-Assistenzsystems vor, welches strukturmechanische Finite-Elemente (FE) Simulationen auf Plausibilität überprüft und auftretende Fehler möglichst automatisiert zu erkennt und behebt. Hierbei werden die einzelnen Module und deren Verknüpfungen untereinander und zu anderen Anwendungen vorgestellt.
Keywords: FEA-Assistenzssstem; FEdelM; Plausibilitätsprüfung; FORPRO²

Data-driven analysis of cold-formed pin structure characteristics in the context of versatile joining processes - Römisch, David; Zirngibl, Christoph; Schleich, Benjamin; Wartzack, Sandro; Merklein, Marion (IOP Conference Series, 2021)
Due to increasingly strict emission targets and regulatory requirements, especially for companies in the transport industry, the demand for multi-material-systems is continuously rising in order to lower energy consumption. In this context, mechanical joining processes offer an environmentally friendly and flexible alternative to established joining methods, especially in the field of lightweight design. For example, cold-formed cylindrical pin structures show high potentials in joining multi-material-systems without auxiliary elements. The pin structures are joined either by pressing them directly into the joining partner or by caulking with a pre-punched part. However, to evaluate the strength of the joint and to ensure the joining reliability for versatile processes, such as changing joining partners or batch variations, engineering designers currently have only limited design principles available compared to thermal joining processes. Consequently, the design of an optimal pin joint requires cost- and time-intensive experimental investigations and adjustments to design or process parameters. As a solution, data-driven methods offer procedures for structuring data and identifying dependencies between varying process parameters and resulting pin structure characteristics. Motivated by this, the paper presents an approach for the data-driven analysis of cold-formed pin structures and offers a deeper understanding of how versatile processes affect the pin characteristics. Therefore, the application of an intelligent design of experiment in combination with several machine learning methods enable the setup of a best-fitting meta-model. Resulting, the determination of a mathematical model provides the opportunity to accurately estimate the pin height considering only relevant geometrical and process parameters with a prediction quality of 95

Data-driven design challenges in the early stages of the product development process - Briard, Tristan; Jean, Camille; Aoussat, Améziane; Véron, Philippe; Le Cardinal, Julie; Wartzack, Sandro (Proceedings of the Design Society, 2021)
With the rapid development of digital technologies, products connectivity is increasing as well as the data produced and collected. Forecasts on product development predict that this trend will keep on growing. In this context, new design solutions based on data are emerging. Those data-driven design approaches are common for identifying the customers’ need when developing a new product. However, few studies cover data-driven design in the other early stages of product design. Thus, the research question addressed in this paper is: what are the challenges of data-driven design research in the early phases of the product development process? Through a literature review and a workshop proposed at the conference DESIGN 2020, this paper offers a first glimpse of future research leads. A list of 5 challenges for data-driven design in the early stages of product design is proposed and ranked from short term to long term.
CRIS-Team Scopus Importer:2021-11-05
Keywords: Big data; Data-driven design; Design practice; Early design phases; Internet of Things

Data Driven Design Selection and Generation - An Industrial Case Study on Electric Motors - Tüchsen, Johann; Pop, Adrian-Cornel; Koch, Matthias; Schleich, Benjamin; Wartzack, Sandro (DESIGN 2018 - 15th International Design Conference, 2018)
This paper presents a novel design selection and generation mechanism for fast and efficient solution-finding based on the knowledge-based systems concept. Such a mechanism can be fully exploited in the early design phases (i.e. quotation phase), when the supplier has to propose both a technically feasible and pricewise attractive solution to the OEM's request. The benefits of the presented method are a massive time reduction from several weeks to less than one day as well as an improvement of the overall solutions quality as all possible technologies are evaluated parallel.<br
Keywords: selection and generation; electric motor design; data driven design; knowledge based engineering (KBE); decision making

Data driven product portfolio analysis of electric motors based on product platforms using knowledge-based systems - Tüchsen, Johann; Pop, Adrian-Cornel; Koch, Matthias; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the 22nd International Conference on Engineering Design (ICED19), 2019)
For a company it is necessary to know, which products can be configured using carry-over-parts or the same technology. This can become quite relevant in the context of automobile electrification, where complex mechatronic systems are used. Consisting of various mechanical components, these systems perform the required function while being actuated by electronically controlled motors. To solve this, a novel mechanism for data driven portfolio analysis based on product platforms using knowledge-based systems is proposed in this paper. Further, the mechanism is tested by applying it to an electrical motors' case study. Using this method, all possible combinations of a product platform are calculated and finally displayed in different product portfolios. Additionally, all the non-feasible motor designs are removed from the solutions portfolio using the acquired knowledge base and performing design checks. The latter are employed for penalising and eliminating from the pareto-front of the designs, which violate the thermal, mechanical and acoustic constraints. The generated product portfolio can be used further to expand the systems engineering collaboration and support decision-making.<br
Keywords: Knowledge-Based Systems; Electric Motors; Platform strategies; Portfolio management; Knowledge management

Datenakquisition und -analyse im Assistenzsystem zur lärmreduzierten Auslegung rotierender Maschinen - Küstner, Christof; Wachsmuth, Philipp; Wartzack, Sandro (Beiträge zum Stuttgarter Symposium für Produktentwicklung (SSP2015), 2015)
In diesem Beitrag wird die Datenakquisition und -analyse der wissensbasierten Navigation des Assistenzsystems (AS) ALARM für die lärmreduzierte Auslegung rotierender Maschinen vorgestellt. Zu Beginn werden die Wissensakquisitionskomponenten unterschiedlicher AS diskutiert. Danach wird der Prozess der Datenakquisition und -analyse und die Struktur der Wissensbasis des AS ALARM vorgestellt. Im Anschluss wird die Datenakquisition gezeigt, die so konzipiert ist, dass möglichst alle erhobenen Daten im Produktentwicklungsprozess ins AS ALARM überführt werden können. Hierzu wird eine Unterteilung der Daten in Datentupel und Datensätze vorgenommen, sowie die Datenquellen spezifiziert. Anhand eines Anwendungsbeispiels wird abschließend gezeigt, wie der Produktentwickler bei der Datenakquisition unterstützt wird.
UnivIS-Import:2015-10-26:Pub.2015.tech.FT.FT-KLMEFK.datena
Keywords: Assistenzsystem; Wissensakquisition; Datenakquisition; Schall und Schwingungen

Deep learning in sheet-bulk metal forming part design - Sauer, Christopher; Schleich, Benjamin; Wartzack, Sandro (DS92: Proceedings of the DESIGN 2018 15th International Design Conference, 2018)
Within the Transregional Collaborative Research Centre 73, a self-learning engineering workbench is being developed. It assists product developers in designing sheet-bulk metal formed (SBMF) parts by computing the effects of given product and process characteristics on the product properties. This contribution presents a novel approach to using deep learning methods for the properties prediction. By making use of a parameter study of 20 SBMF part designs, a metamodel is trained and used to predict the total equivalent plastic strain on local level as an indicator for part manufacturability.<br
Keywords: data mining; data driven design; characteristics and properties; deep learning

Definition, Klassen und Anwendungsmöglichkeiten des Digitalen Zwillings für die Antriebstechnik - Wilking, Fabian; Schleich, Benjamin; Wartzack, Sandro (WiGeP News, 2020)

Demonstration of a new approach for measuring tools with the impingement sound of an air jet using machine learning - Würschinger, Hubert; Gross, Daniel; Stadler, Manuel; Mühlbauer, Matthias; Hanenkamp, Nico (MM Science Journal, 2021)
Monitoring the tool condition of machining processes is important but challenging. Several automated tool condition monitoring solutions are available, but often not used due to existing restrictions or disadvantages. A new approach can be the detection and measurement of tool conditions analyzing the sound of an air jet impingement on tools. Due to the availability of compressed air as a working and cleaning medium for many processes, this approach can be used for various condition monitoring and measuring tasks. In this paper the procedure and its functionality are first presented on simple shapes and then tested on the tool wear of inserts.<br
Keywords: Tool Condition Monitoring; Condition Monitoring; Impingement Sound; Jet Impingement; Air Jet; Flow Noise; Airborne Sound; Machine Learning

Der Einfluss der Sortierung auf das statistische Verhalten von Funktionsmaßen - Aschenbrenner, Alexander; Schleich, Benjamin; Wartzack, Sandro (Design for X. Beiträge zum 28. DfX-Symposium, 2017)
In an automated assembly process, the exchangeability of the components is a necessity. This could imply harsh requirements concerning the geometric definition and tolerancing of components. The classification of components is one way to decrease these requirements. Classification used to be limited to manual assembly and small-scale production. Advances in online measuring technology make the classification of components also applicable for mass fabrication. Employing classification, accuracy and process capability of the production could be increased. Besides these positive effects, classification also poses some challenges for the variation simulation. This contribution addresses approaches on how to tackle these challenges and which effects can arise from classification.
Keywords: Sorting and Classification; Combinatorial Analysis; Variation Simulation; Tolerance Management

Der Einfluss von Drehzahl- und Lastkollektiven auf das Reibungsverhalten von Wälzlagern - Stahl, Thomas; Tremmel, Stephan; Meerkamm, Harald (Gleit- und Wälzlagerungen, VDI-Berichte 2069, 2009)
UnivIS-Import:2015-04-16:Pub.2009.tech.FT.FT-KLMEFK.derein

Derivation and Validation of Linear Elastic Orthotropic Material Properties for Short Fibre Reinforced FLM Parts - Witzgall, Christian; Völkl, Harald; Wartzack, Sandro (Journal of Composites Science, 2022)
Additively manufactured parts play an increasingly important role in structural applications. Fused Layer Modeling (FLM) has gained popularity due to its cost-efficiency and broad choice of materials, among them, short fibre reinforced filaments with high specific stiffness and strength. To design functional FLM parts, adequate material models for simulations are crucial, as these allow for reliable simulation within virtual product development. In this contribution, a new approach to derive FLM material models for short fibre reinforced parts is presented; it is based on simultaneous fitting of the nine orthotropic constants of a linear elastic material model using six specifically conceived tensile specimen geometries with varying build direction and different extrusion path patterns. The approach is applied to a 15 wt.% short carbon-fibre reinforced PETG filament with own experiments, conducted on a Zwick HTM 5020 servo-hydraulic high-speed testing machine. For validation, the displacement behavior of a geometrically more intricate demonstrator part, printed upright, under bending is predicted using simulation and compared to experimental data. The workflow proves stable and functional in calibration and validation. Open research questions are outline
Keywords: short fibre reinforced plastics; SFRP; fused layer modeling; FLM; fused deposition modeling; FDM; material models; simulation

Der KTmfk und die Arbeitsgruppe "Toleranzmanagement" - Wartzack, Sandro; Walter, Michael; Schleich, Benjamin; Aschenbrenner, Alexander; Heling, Björn (Summer School Toleranzmanagement - Beiträge zur 2. Summer School - September 2015, 2015)

Design and Additive Manufacturing of a Passive Ankle–Foot Orthosis Incorporating Material Characterization for Fiber-Reinforced PETG-CF15 - Steck, Patrick; Scherb, David; Witzgall, Christian; Miehling, Jörg; Wartzack, Sandro (Materials, 2023)
The individualization of patient-specific ankle joint orthoses is becoming increasingly important and can be ideally realized by means of additive manufacturing. However, currently, there are no functional additively manufactured fiber-reinforced products that are used in the field of orthopedic treatment. In this paper, an approach as to how additively manufactured orthopedic products can be designed and produced quickly and flexibly in the future is presented. This is demonstrated using the example of a solid ankle–foot orthosis. For this purpose, test results on PETG-CF15, which were determined in a previous work, were integrated into a material map for an FEA simulation. Therewith, the question can be answered as to whether production parameters that were determined at the test specimen level can also be adapted to real, usable components. Furthermore, gait recordings were used as loading conditions to obtain exact results for the final product. In order to perfectly adapt the design of the splint to the user, a 3D scan of a foot was performed to obtain a perfect design space for topology optimization. This resulted in a patient-specific and stiffness-optimized product. Subsequently, it was demonstrated that the orthosis could be manufactured using fused layer modelling. Finally, a comparison between the conventional design and the consideration of AM-specific properties was made. On this basis, it can be stated that the wearing comfort of the patient-specific design is very good, but the tightening of the splint still needs to be improved.<br
Keywords: ankle–foot orthoses; additive manufacturing; ankle splints; fused layer modelling; topology optimization; fiber reinforcement; material characterization; user-centered design

Design Criteria for Oil Ring Lubricators to Improve Maintainability of Rolling Bearings - Müller, Matthias; Tremmel, Stephan (STLE 71st Annual Meeting & Exhibition, 2016)
Keywords: Rolling Element Bearings; Ring Lubrication; Maintainability; Lubricant Degradation

Design Criteria for Oil Ring Lubricators to Improve Maintainability of Rolling Bearings - Müller, Matthias; Tremmel, Stephan (2016)
Keywords: Ring Lubricator; Rolling Element Bearings; Oil Lubrication

Design for composites: Derivation of manufacturable geometries for unidirectional tape laying - Völkl, Harald; Kießkalt, Andreas; Wartzack, Sandro (Proceedings of the 22nd International Conference on Engineering Design (ICED19), 2019)
Even though providing excellent specific stiffness and strength properties, high specific energy absorption and a great degree of design freedom, fibre-reinforced plastics still have to make their way into higher volume applications. Addressing the manufacturing challenges, particularly efficient production techniques are Automated Tape Laying (ATL) and Automated Fiber Placement (AFP), as pointed out by various studies and use cases. However, current Computer Aided Engineering approaches for optimised laminate design still lack the capability to produce results suitable for ATL/AFP. A new method for deriving tape courses from any finite element laminate optimisation result is presented and applied to a virtual demonstrator. An outlook is given on further necessities of extending current laminate optimisation approache
Keywords: Optimisation; Computational design methods; Design for X (DfX); Fibre Reinforced Plastics; Manufacturing

Design for composites: Tailor-made, bio-inspired topology optimization for fiber-reinforced plastics - Völkl, Harald; Wartzack, Sandro (DESIGN 2018 - 15th International Design Conference, 2018)
A bio-inspired topology optimization approach with simultaneous fiber orientation optimization for fiber-reinforced plastics is introduced. To scrutinize the optimization potential of the new approach when compared to methods not considering fiber orientation during the optimization process, a case study using a bike rocker arm is presented. In this study, slightly better stiffness behavior of the new approach compared to its counterparts could be observed. However, as far as strength behavior (matrix failure) is concerned, significant gains could be achieved, both in numbers and visually.<br
Keywords: Lightweight Design; Bio-inspired design; Topology optimization; Fiber-reinforced plastics

Design for Friction Reduction – Durchgängige Unterstützung des Konstrukteurs durch den gezielten Einsatz von Wälzlagerreibungs-Berechnungswerkzeugen - Seiler, Katrin; Tremmel, Stephan; Wartzack, Sandro (25. DfX-Symposium, 2014)
Keywords: Wälzlager; Reibung; MKS; Tribologie; Hydrodynamik

Design-for-manufacture of sheet-bulk metal formed parts - Breitsprecher, Thilo; Sauer, Christopher; Sperber, Christian; 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.design

Design for mobility - A methodical approach - Schmidt, Johanna; Krüger, Daniel; Eilmus, Sandra; Paetzold, Kristin; Wartzack, Sandro; Krause, Dieter (Proceedings of DESIGN 2012, the 12th International Design Conference, 2012)
UnivIS-Import:2015-04-16:Pub.2012.tech.FT.FT-KLMEFK.design_9
Keywords: Design for the elderly; Digital human modeling; Mobility; Product family; Variety

Design for noise reduction – The architecture of an engineering assistance system for the development of noise-reduced rotating systems - Küstner, Christof; Breitsprecher, Thilo; Wartzack, Sandro (DS 75-5: Proceedings of the 19th International Conference on Engineering Design (ICED13), 2013)
Despite detailed planning, conceptual and embodiment design important product properties like the acoustical behavior of complex machinery are only revealed in the later development phases (e. g. prototyping phase). If annoying acoustical behavior of machinery is identified in the later development phases, there will be the need to time- and money-consuming macro-iterations, which sometimes go back to the conceptual phase. This means a high financial risk especially for capital goods like wind turbines, because the operating license of wind turbines can be refused. In this paper, the demands and the basic architecture of a knowledge-based engineering (KBE) assistance system for the development of noise reduced rotating machines will be presented. It will assist the development engineers by context-sensitive allocation of design-relevant knowledge that enables them to identify components of complex machinery which are critical with respect to noise creation, noise transmission or noise radiation. With the aid of this assistance system, which is called ALARM, the risk of a drop back to the conceptual phase regarding undesirable acoustic product properties will be reduced.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.design
Keywords: Design for x; Information management; Knowledge management; Knowledge-based engineering; Wind energy

Design for X (DFX) - Wartzack, Sandro; Meerkamm, Harald; Bauer, Stefan; Krehmer, Hartmut; Stockinger, Andreas; Walter, Michael; Schleich, Benjamin (Handbuch Konstruktion, 2018)
Erfolgreiche Produkte müssen sowohl die Kundenanforderungen als auch die Restriktionen erfüllen, die sich aus dem gesamten Produktenstehungsprozess und -lebenszyklus, d. h. von der Fertigung bis hin zur Entsorgung ergeben. In der Konzeptphase, vor allem aber beim Entwerfen, haben die Entwickler und Konstrukteure eine Fülle von Gestaltungsrichtlinien zu beachten, die sich in ihrer Gesamtheit unter dem Kürzel DFX (Design for X) subsumieren lassen. Natürlich ist die Erfüllung der Funktion die wichtigste Hauptforderung bei der Konstruktion eines Produkts. Darüber hinaus gilt es aber, eine Vielzahl von gegenseitig vernetzten Forderungen und Restriktionen unter Abwägung ihrer Wichtigkeit/Gewichtung zu berücksichtigen (Ehrlenspiel 2009). Dabei ist zu beachten, dass vor allem die frühen Phasen des Konstruktionsprozesses von entscheidender Bedeutung sind, denn hier werden bekanntlich zwei Drittel aller Produkteigenschaften festgelegt. DFX steht einerseits für ein umfassendes und komplexes Wissensgebiet aus zum Teil verschiedenen Fachdomänen, andererseits aber auch für eine geeignete methodische Vorgehensweise mit Entscheidungen zwischen sich zum Teil widersprechenden Aspekten und dem Einsatz leistungsfähiger Methoden und vor allem aber rechnerunterstützter Werkzeuge. DFX kann auch verstanden werden als eine ganzheitliche Denkweise (Philosophie), die den Konstrukteuren zweifache Unterstützung bieten kann – und zwar als eine Organisationshilfe, mit der sich die grundlegenden Randbedingungen für ein Produkt bereits in der Planungs- und Konzeptphase festlegen lassen, und als detaillierte Beschreibungen/Richtlinien für die Konstrukteure, nach denen sich in den späten Phasen des Produktenwicklungsprozesses die Gestalt eines Produktes bestimmen lässt. Es muss festgehalten werden, dass der Begriff DFX in der industriellen Praxis noch wenig gebräuchlich ist, obwohl sich doch alle Entwicklungs- und Konstruktionsprozesse um diese Thematik drehen. Vielfach hat sich in jüngster Zeit in Unternehmen der Begriff Frontloading etabliert. DFX ist in der hier aufzuzeigenden begrifflichen Strenge und stringenten Strukturierung sowie Anwendung von Methoden und Werkzeugen vor allem in der Forschungslandschaft geläufig. Gleichwohl sind die hier angesprochenen Inhalte für die Praxis von hoher Relevanz.<br

Designing Amorphous Carbon Coatings Using Numerical and Experimental Methods within a Multi-Scale Approach - Tremmel, Stephan; Marian, Max; Rothammer, Benedict; Weikert, Tim; Wartzack, Sandro (14th International Conference THE A Coatings, 2020)
Amorphous carbon coatings have the potential to effectively reduce friction and wear in tribotechnical systems. The appropriate application of amorphous carbon layers requires both, a very good understanding of the tribological system and knowledge of the relationships between the fabrication of the coatings and their properties. In technical practice, however, the coatings’ development and their selection on the one hand and the design of the tribological system and its environment on the other hand are usually very strongly separated. The present work therefore aims to motivate the integrated development of tribotechnical systems with early consideration of the potential of amorphous carbon coatings. An efficient integrated development process is presented, which makes it possible to determine the boundary conditions and the load collective of the tribological system based upon an overall system and to derive the requirements for a tailored coating. In line with the nature of tribology, this approach must cover several scales. In this respect, the development process follows a V-model. The left branch of the V-model is mainly based upon a simulation chain including multibody and contact simulations. The right branch defines an experimental test chain comprising coating characterization to refine the contact simulation iteratively and tribological testing on different levels to validate the function fulfillment. Within this contribution, the outlined approach is illustrated by two use cases, namely the cam/tappet-pairing and the total knee replacement.<br
Keywords: Coating; Design Method; Tribology

Designing Amorphous Carbon Coatings Using Numerical and Experimental Methods within a Multi-Scale Approach - Tremmel, Stephan; Marian, Max; Rothammer, Benedict; Weikert, Tim; Wartzack, Sandro (Defect and Diffusion Forum, 2020)
Amorphous carbon coatings have the potential to effectively reduce friction and wear in tribotechnical systems. The appropriate application of amorphous carbon layers requires both, a very good understanding of the tribological system and knowledge of the relationships between the fabrication of the coatings and their properties. In technical practice, however, the coatings’ development and their selection on the one hand and the design of the tribological system and its environment on the other hand are usually very strongly separated. The present work therefore aims to motivate the integrated development of tribotechnical systems with early consideration of the potential of amorphous carbon coatings. An efficient integrated development process is presented, which makes it possible to determine the boundary conditions and the load collective of the tribological system based upon an overall system and to derive the requirements for a tailored coating. In line with the nature of tribology, this approach must cover several scales. In this respect, the development process follows a V-model. The left branch of the V-model is mainly based upon a simulation chain including multibody and contact simulations. The right branch defines an experimental test chain comprising coating characterization to refine the contact simulation iteratively and tribological testing on different levels to validate the function fulfillment. Within this contribution, the outlined approach is illustrated by two use cases, namely the cam/tappet-pairing and the total knee replacement.
Keywords: Tribology; Coating; Design method

Designing lightweight structures under consideration of material and structure uncertainties on different levels of the building block approach - Hartwich, Tobias S.; Völkl, Harald; Wartzack, Sandro; Krause, Dieter (Proceedings of the 31st Symposium Design for X, DFX 2020, 2020)
Lightweight design is an important aspect in the development of components to reduce material use and obtain energy-efficient structures. Frequently, lightweight structures are designed for one or a few load cases. Therefore, optimized designs can be less robust against changes in boundary conditions, scattering material parameters or deviating tolerances. Thus, these structures must be designed with safety factors that counteract the targeted lightweight design goal. In this article, an approach for the consideration of uncertainties is presented. The approach allows evaluating potentials of the accurate consideration of uncertainties. Finally, the developed approach is implemented for the calculation of the buckling load and torsional strength of thin-walled CFRP cylinderical shells.
CRIS-Team Scopus Importer:2021-04-19
Keywords: Buckling; Building Block Approach; CFRP; Lightweight Design; Uncertainties

Designing of hybrid joints at the early embodiment design stage - Kellermeyer, Markus; Klein, Daniel; 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.design_9
Keywords: Leichtbau; Composites; Simulation

Designing surface textures for EHL point-contacts - Transient 3D simulations, meta-modeling and experimental validation - Marian, Max; Grützmacher, Philipp; Rosenkranz, Andreas; Tremmel, Stephan; Mücklich, Frank; Wartzack, Sandro (Tribology International, 2019)
Micro-textures applied on rubbing surfaces have gained tremendous attention in the tribological community. Numerous studies deal with the deduction and testing of beneficial micro-textures. Nevertheless, not all questions have been answered yet. Will texturing really deliver as good effects as frequently claimed? Are there optimum texture designs? Are there occasions where texturing could enhance the tribological performance but is questionable from other perspectives? Therefore, ball-on-disc experiments are carried out with a special emphasis on the relative position of micro-texture and counter body. Furthermore, transient EHL simulations are performed, addressing the effects of structural parameters and relative texture's position on the tribological performance. Finally, meta-modeling with subsequent optimization is applied to predict numerically derived optima and robust texture designs.
Keywords: Surface texturing; Elastohydrodynamic lubrication; Optimization; Texture design

Design, Manufacturing and Tribological Performance of Microtextured Bucket Tappets for Friction Reduction in the Valve Train - Marian, Max; Zahner, Michael; Tremmel, Stephan; Andreas, Kolja; Merklein, Marion; Wartzack, Sandro (6th World Tribology Congress, 2017)
In order to improve lubricating conditions as well as friction and wear behavior, the surfaces of contacting bodies in lubricated tribological contacts can be microtextured. While this approach has already reached industrial application for lower loaded contacts, the effects for higher loaded contacts, where elastic deformation plays a significant role, are still topic of basic research. For this reason, microtextures are adapted to the conditions of the tribological system of the bucket tappet/camshaft contact in the valve train as a demonstrator and major contributor to combustion engine losses. The tribological performance of various microtexture geometries and arrangements is analyzed on a one bucket tappet/one cam test-rig using series production valve train parts. A resistive measurement system is first applied to the highly dynamic tappet/camshaft contact and allows the investigation of the correlation between lubricating conditions and friction force. In the tests, a significant friction force reduction using microtextured surfaces compared to polished surfaces is achieved. Additionally, quantitative ex-situ wear characterization is carried out for long-run test cycles, using Laser Scanning Microscopy. Thus, wear mechanisms and rates are compared with the measurements of lubricating conditions and friction force. Besides the identification of advantageous microtexture geometries and arrangements regarding the tribological performance, possibilities and limitations of the manufacturing technology are examined. In order to realize high-volume production, a micro coining process was studied. In this regard the manufacturing of the coining punch using µEDM and the coining process itself were analyzed with respect to accuracy and reproducibility. Additionally, the durability of the pins was investigated for the micro coining process. The limitations of the manufacturing process and of the micro coining process are summarized in a process windo
Keywords: Microtextures; Micro Coining; EHL Contact

Design of Amorphous Carbon Coatings Using Gaussian Processes and Advanced Data Visualization - Sauer, Christopher; Rothammer, Benedict; Pottin, Nicolai; Bartz, Marcel; Schleich, Benjamin; Wartzack, Sandro (Lubricants, 2022)
In recent years, an increasing number of machine learning applications in tribology and coating design have been reported. Motivated by this, this contribution highlights the use of Gaussian processes for the prediction of the resulting coating characteristics to enhance the design of amorphous carbon coatings. In this regard, by using Gaussian process regression (GPR) models, a visualization of the process map of available coating design is created. The training of the GPR models is based on the experimental results of a centrally composed full factorial 23 experimental design for the deposition of a‑C:H coatings on medical UHMWPE. In addition, different supervised machine learning (ML) models, such as Polynomial Regression (PR), Support Vector Machines (SVM) and Neural Networks (NN) are trained. All models are then used to predict the resulting indentation hardness of a complete statistical experimental design using the Box–Behnken design. The results are finally compared, with the GPR being of superior performance. The performance of the overall approach, in terms of quality and quantity of predictions as well as in terms of usage in visualization, is demonstrated using an initial dataset of 10 characterized amorphous carbon coatings on UHMWPE.
Keywords: Machine Learning; Amorphopus Carbon Coatings; UHWMPE; Total Knee Replacement; Gaussian Processes

Design of compliant mechanisms with selective compliance - Hasse, Alexander; Campanile, Lucio Flavio (Smart Materials & Structures, 2009)
Conventional mechanisms provide a defined mobility, which expresses the number of degrees of freedom of the mechanism. This allows the system to be driven by a low number of control outputs. This property is virtually retained in the case of compliant mechanisms with lumped compliance, which are obtained by replacing the conventional hinges by solid-state ones. Compliant mechanisms with distributed compliance have, in general, an infinite number of degrees of freedom and therefore cannot guarantee defined kinematics. In this paper the concept of compliant mechanisms with selective compliance is introduced. This special class of compliant mechanisms combines the advantages of distributed compliance with the easy controllability of systems with defined kinematics. The task is accomplished by introducing a new design criterion based on a modal formulation. After this design criterion has been implemented in an optimization formulation for a formal optimization procedure, mechanisms are obtained in which a freely chosen deformation pattern is associated with a low deformation energy while other deformation patterns are considerably stiffer. Besides the description of the modal design criterion and the associated objective function, the sensitivity analysis of the objective function is presented and an application example is shown. © 2009 IOP Publishing Ltd.
Keywords: Application examples; Compliant mechanism; Deformation energy; Deformation pattern; Design criterion; Infinite numbers; New design; Number of degrees of freedom; Objective functions; Optimization formulations; Optimization procedures; Special class

Design of process parameters for the manufacturing of wrapped connections with single solid round wires using the explicit finite element analysis - Hefner, Florian; Praß, Julian; Kirchner, Philipp; Franke, Jörg (Procedia CIRP, 2020)
Keywords: process simulation; wrapped connections; explicit finite element analysis

Design of the Load Introduction of Continuous Fibre-Reinforced Components for Cyclic Loading - Deutschmann, Torben; Gadinger, Marc; Wartzack, Sandro; Krause, Dieter (Proceedings of the 35th Symposium Design for X (DFX2024), 2024)
The use of fibre-reinforced plastics (FRP) in structural components offers significant lightweight potential due to their high specific stiffness and strength. However, the complex fatigue behavior of FRP often leads to insufficient consideration of long-term strength during product development, which is typically compensated for by high safety factors. This study aims to explore additional lightweight potential by addressing fatigue phenomena more accurately, focusing on the critical area of load introduction. Bolted connections, commonly used for load introduction, are prone to bearing failure under cyclic loading. Therefore, a simplified design support for the load introduction in cyclically loaded FRP components is necessar
Keywords: Fibre-reinforced Plastics; Lightweight Design; Fatigue; Load Introduction

Detection and Classification of Symbols in Principle Sketches using Deep Learning - Bickel, Sebastian; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the International Conference on Engineering Design (ICED21), 2021)
Data-driven methods from the field of Artificial Intelligence or Machine Learning are increasingly applied in mechanical engineering. This refers to the development of digital engineering in recent years, which aims to bring these methods into practice in order to realize cost and time savings. However, a necessary step towards the implementation of such methods is the utilization of existing data. This problem is essential because the mere availability of data does not automatically imply data usability. Therefore, this paper presents a method to automatically recognize symbols from principle sketches, which allows the generation of training data for machine learning algorithms. In this approach, the symbols are created randomly and their illustration varies with each generation. . A deep learning network from the field of computer vision is used to test the generated data set and thus to recognize symbols on principle sketches. This type of drawing is especially interesting because the cost-saving potential is very high due to the application in the early phases of the product development proces
Keywords: Artificial intelligence Machine learning Early design phases

Detection of Plausibility and Error Reasons in Finite Element Simulations with Deep Learning Networks - Bickel, Sebastian; Götz, Stefan; Wartzack, Sandro (Algorithms, 2023)
The field of application of data-driven product development is diverse and ranges from requirements through the early phases to the detailed design of the product. The goal is to consistently analyze data to support and improve individual steps in the development process. In the context of this work, the focus is on the design and detailing phase, represented by the virtual testing of products through Finite Element (FE) simulations. However, due to the heterogeneous data of a simulation model, automatic use is a big challenge. A method is therefore presented that utilizes the entire stock of calculated simulations to predict the plausibility of new simulations. Correspondingly, a large amount of data is utilized to support less experienced users of FE software in the application. Thus, obvious errors in the simulation should be detected immediately with this procedure and unnecessary iterations are therefore avoided. Previous solutions were only able to perform a general plausibility classification, whereas the approach presented in this paper is intended to predict specific error sources in FE simulations.<br

DETECTION OF SINGULARITIES IN FINITE ELEMENT SIMULATIONS: A 3D DEEP LEARNING APPROACH - Bickel, Sebastian; Götz, Stefan; Wartzack, Sandro (Proceedings of the ASME Design Engineering Technical Conference, 2023)
The growing digitalization trend has a great influence and impact on the entire product development domain. The new algorithms and methods transform and improve many established processes and workflows. In addition to converting existing know-how into the new processes, available data can also be used to implement various models to enhance the development process. At the same time, the lack of experienced engineers leads to an increasing number of novice engineers from the field of 3D design, who have to perform tasks from the simulation department. Therefore, support for these less experienced users of product development software through newly available methods from the field of data-driven methods is reasonable. Correspondingly, the goal of this paper is to present a method for singularity detection in Finite Element (FE) simulations that detects the presence of a singularity in a computed simulation with the help of Deep Learning. For this purpose, a dataset of calculated simulations with several components with and without singularities is first generated. Then, a new approach based on PointNet and labeled datasets of FE simulations is proposed. Afterwards, the new procedure is compared against a classic Machine Learning approach, whereby different parameter settings were investigated for both approaches.
CRIS-Team Scopus Importer:2023-12-15
Keywords: Data-Driven Product Development; Deep Learning; Finite Element Simulation; Machine Learning

Determination of the Young´s Modulus of Hard Coatings on Soft Polymer Substrates - Sander, Thomas; Tremmel, Stephan; Wartzack, Sandro (40th International Conference on Metallurgical Coatings and Thin Films ICMCTF 2013, 2013)
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.determ

Determining the influence of different process parameters on the versatile self-piercing riveting process using numerical methods - Kappe, Fabian; Zirngibl, Christoph; Schleich, Benjamin; Bobbert, Mathias; Wartzack, Sandro; Meschut, Gerson (Journal of Manufacturing Processes, 2022)

Development and Evaluation of Tool Sided Surface Modifications for Dry Deep Drawing of Steel and Aluminum Alloys - Merklein, Marion; Schmidt, Michael; Wartzack, Sandro; Tremmel, Stephan; Andreas, Kolja; Häfner, Tom; Zhao, Rong; Steiner, Jennifer (Dry Metal Forming Open Access Journal, 2015)

Development of a hoop-strength test for model sphero-cylindrical dental ceramic crowns: FEA and fractography - Belli, Renan; Völkl, Harald; Csato, Stefan; Tremmel, Stephan; Wartzack, Sandro; Lohbauer, Ulrich (Journal of the European Ceramic Society, 2020)
Here we describe the development of a mechanical test that simulates a circumferential “hoop-stress” at the margins of model dental ceramic crowns. A simplified sphero-cylindrical geometry was modelled in two thicknesses and machined out of two glass-ceramic materials. The specimens were loaded by a conical metallic piston to induce circumferential hoop-stresses at the margins until fracture. Broken specimens were fractographically analyzed to determine the location of the fracture origin and to measure the dimensions of the critical defect, allowing the calculation of the stress at failure from fracture mechanics relations. For thick specimens, machining defects at the outer margins barely played a role in fracture initiation. For thin specimens, outer defects started to dominate the failure mode. CAD/CAM machining showed to predispose thinner margins to early fracture. Crowns should be designed with increased thickness in order to minimize the effect of marginal damage in the circumferential stress field inducing fracture.
CRIS-Team Scopus Importer:2020-02-14
Keywords: Dental; Finite element analysis; Fractography; Glass-ceramic; Mechanical test

Development of a Toolkit of Methods for Simulations in Product Development - Carro Saavedra, Cristina; Marahrens, Nils-Jorge; Schweigert, Sebastian; Kestel, Philipp; Kremer, Simon; Wartzack, Sandro; Lindemann, Udo (IEEE International Conference on Industrial Engineering and Engineering Management (IEEM), 2016)
Simulations contribute to the efficiency of the product development process and the quality of the developed products. However, their integration in the development process can be improved. We propose a knowledge-based framework, containing a toolkit of simulation methods as its central element to integrate simulations in the product development process. Within this paper, we briefly introduce the knowledge-based framework and we present the toolkit structure and the methodology for its development.

DFG-Forschergruppe "Prozessorientiertes Toleranzmanagement" an der FAU gestartet - Wartzack, Sandro; Schleich, Benjamin; Heling, Björn (WiGeP News, 2016)
Fünf Lehrstühle der FAU Erlangen-Nürnberg forschen gemeinsam an Fragestellungen des ganzheitlichen Toleranzmanagements

Diamant auf Stahl. Diffusionschromierung im Vakuum für die CVD-Diamantbeschichtung - Schwarz, Sergej; Musayev, Yashar; Rosiwal, Stefan (Magazin für Oberflächentechnik, 2001)
UnivIS-Import:2015-03-09:Pub.2001.tech.IW.LWWTM.diaman

Diamond-like Carbon Coatings for Artificial Implant - Rothammer, Benedict; Marian, Max (Applications of Diamond‐like Carbon Coatings, 2025)
This chapter delves into the enhancement of implant performance through diamond-like carbon (DLC) coatings, recognized for their exceptional mechanical, chemical, and biocompatible properties, making them ideal for various biomedical applications. The chapter focuses on orthopedic applications, where DLC coatings improve wear resistance and longevity of implants, and promote osteointegration by enhancing cell adhesion and proliferation. In dental implants, DLC coatings boost biocompatibility and reduce infection risk, while also enhancing the durability of orthodontic brackets. This chapter details the requirements for DLC coatings in artificial implants and reviews their use in load bearing and dental implants, respectively. The chapter concludes with a summary of findings and identifies future research challenges, emphasizing the need for translating model-level advancements to component-level applications and addressing the reproducibility issues in dental applications. Overall, DLC coatings show significant potential to improve patient outcomes, reduce revision surgeries, and enhance comfort in both orthopedic and dental medicin

Die Auswirkung der Reihenfolge von Mess- und Simulationsdaten auf das Ergebnis der Kreuzvalidierung in KDD Prozessen - Küstner, Christof; Breitsprecher, Thilo; Wartzack, Sandro (Design for X - Beiträge zum 24. DfX-Symposium 2013, 2013)
Knowledge Discovery in Databases (KDD) is an emerging computer-aided methodology that enables design engineers to acquire design-relevant knowledge from complex data. Sources for this data are experiments and simulations in nearly every domain that is related to the product life cycle (e. g. structural mechanics, manufacturing engineering, prototyping). The inter-European research project EUREKA ALARM (assistance system for the development of noise reduced rotating machines), inter alia, aims at the automatic knowledge acquisition from data sources like multi body simulation results and noise measurements of modern wind turbines. The design-relevant knowledge is represented by so called metamodels, behavior or surrogate models. These models enable the design engineer to predict the noise behavior of a wind turbine, based on different parameters like gear geometry, gear number, etc.. It is obvious that design engineers need to estimate the prediction quality of the models quantitatively for example by means of prediction performance values as relative prediction error, root mean squared error or root mean absolute error. The use of metamodels with poor prediction behavior are of cause not the objective of KDD methodology. In order to derive these performance values different procedures are suggested according to KDD literature, whereas the k-fold cross validation is the most common one. To ensure a statistically robust performance estimation it is advised to repeat this procedure which has led to a ten-times ten-fold cross validation. During the research efforts of ALARM a new issue appeared. It can be shown that the structure of the input dataset has an impact on the performance estimation. In this contribution an approach is presented how to handle this issue.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.dieaus

Die Auswirkungen von Axialschwingungen auf Reibung, Verschleiß und Schmierung in Zylinderrollenlagern - Meinel, Andreas; Tremmel, Stephan (59. Tribologie-Fachtagung. Reibung, Schmierung und Verschleiß. Forschung und praktische Anwendungen. Band 1, 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 is being subjected to dynamic axial shaft movements of various frequencies and amplitudes, utilizing a specifically designed test rig. Within the scope of this paper, 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, friction losses as well as wear measurements are subsequently presented. Finally, a brief assessment is given, to what extent axial shaft movements exert a critical influence on friction, lubrication and wea

Die Crux der Faserorientierung - Klein, Daniel; Gruber, Georg; Wartzack, Sandro (Kunststoffe, 2014)
UnivIS-Import:2015-10-26:Pub.2014.tech.FT.FT-KLMEFK.diecru
Keywords: Leichtbau; Composites; kurzfaserverstärkte Thermoplaste

Die eigenschaftsbasierte Produktentwicklung unter Berücksichtigung der differenziellen Anforderungen älterer Nutzer - Luft, Thomas; Kamin, Stefan; Miehling, Jörg; Lang, Frieder; Wartzack, Sandro (Design for X: Beiträge zum 24. DfX-Symposium 2013, 2013)
Population aging is one of the most important challenges in human history. Adapting this challenge involves the development of products and services for improving activity, health and quality of life in old age. The development of such products requires interdisciplinary collaboration between disciplines of aging and engineering sciences. This involves integrating the specific needs of older users into product development. The aim of this work is to describe a methodical approach combining behavioural and psychological perspectives on technology use in old age with engineering sciences. This interdisciplinary procedure is described based on the development of a bicycle for improving mobility in old age and focused on the analysis and assessment of differential user requirements. These requirements are translated into a matrix-based product description allowing product developers to derive product properties and to set the required characteristics for each of these properties. As a consequence, this approach may contribute to the improved development of innovative products in old ag
Keywords: design methodology; property-based product development; matrix-based product description; user-centred design; technology and aging

Die Einbettung des Toleranzmanagements in den Produktentwicklungsprozess - Wartzack, Sandro; Schleich, Benjamin; Walter, Michael; Ziegler, Philipp (Summer School Toleranzmanagement: Beiträge zur 1. Summer School, 2013)
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.dieein

Die matrixbasierte Produktbeschreibung als Bestandteil des Vorgehensmodells in der eigenschaftsbasierten Produktentwicklung - Luft, Thomas; Wartzack, Sandro (Stuttgarter Symposium für Produktentwicklung (SSP), 2013)
Die zentrale Aufgabe von Produktentwicklern besteht darin, die stetig steigenden Anforderungen an Qualität, Kosten und Funktionalität technischer Produkte zu erfüllen, indem durch die Festlegung geeigneter Merkmale die vom Kunden gewünschten Produkteigenschaften realisiert werden. Das Ziel der Autoren ist daher die Entwicklung eines geeigneten Vorgehensmodells in der eigenschaftsbasierten Produktentwicklung, welches die Entwickler zielgerichtet durch den Entwicklungsprozess führt sowie bei der Erfassung des erreichten Produktreifegrades und bei der Durchführung von nötigen Iterationen unterstützt. Die dafür erforderliche matrixbasierte Produktbeschreibung steht im Fokus des Beitrags. Dabei wird das Wechselspiel der Abhängigkeiten zwischen Merkmalen, Eigenschaften und dem daraus resultierenden Verhalten am Beispiel eines Fahrwerkes aufgezeigt.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.diemat
Keywords: Konstruktionsmethodik; eigenschaftsbasierte Produktentwicklung; Vorgehensmodell; matrixbasierte Produktbeschreibung

Die neue VDI-Richtlinie 5610 Blatt 2 „Wissensbasierte Konstruktion“ - Luft, Thomas; Roth, Daniel; Wartzack, Sandro; Binz, Hansgeorg (Stuttgarter Symposium für Produktentwicklung (SSP), 2017)
The targeted and systematic handling of knowledge is a key factor in the product development process. When capturing and formalizing the knowledge relevant for engineering and integrating it into CAD systems one is faced with high requirements. Various methods and tools of Knowledge Based Engineering (abbr. KBE) can help designers to successfully meet those challenges. However, a generally valid description for the realization of KBE applications does not exist yet. Therefore, this paper aims to introduce a procedure for the implementation of KBE applications consisting of the following four phases: planning, development, test, and the operation of a KBE application. Furthermore, the roles involved as well as the issue of knowledge protection are considered. The final chapter introduces basic (software) technical solutions for KBE and one specific implementation of a KBE system application. Ein entscheidender Faktor innerhalb des Produktentwicklungsprozesses ist der zielgerichtete und systematische Umgang mit Wissen. Das konstruktionsrele-vante Wissen zu erfassen, zu formalisieren und in CAD-Systeme zu integrieren ist dabei von hohen Anforderungen geprägt. Verschiedene Methoden und Werkzeuge des „Wissensbasierten Konstruierens“ (Knowledge Based Engineering, kurz: KBE) können Konstrukteure dabei unterstützen, diese Herausforderungen erfolgreich zu bewältigen. Bislang existiert jedoch keine allgemeingültige Beschreibung zur Realisierung von KBE-Anwendungen. Daher ist die Zielsetzung des Beitrags die Vorstellung einer Vorgehensweise zur Umsetzung von KBE-Anwendungen, die sich aus den vier Phasen Planung, Entwicklung, Test sowie Betrieb einer KBE-Anwendung zusammensetzt. Zudem werden beteiligte Rollen und das Thema Wissensschutz betrachtet. Im abschließenden Kapitel erfolgen die Vorstellung grundsätzlicher (software-)technischer Lösungen zum wissensbasierten Konstruieren sowie eine konkrete Implementierung einer KBE-Systemanwendung.
Keywords: Knowledge Management; Knowledge Based Engineering; Construction Methodology; Guideline Activities; Wissensmanagement; Wissensbasierte Konstruktion; CAD; Konstruktionsmethodik; Richtlinienarbeit

Die Rolle des Wissensingenieurs im Unternehmen – Ergebnisse einer Umfrage und Darstellung in der VDI-Richtlinie "Wissensbasiertes Konstruieren" - Luft, Thomas; Breitsprecher, Thilo; Roth, Daniel; Lindow, Kai; Binz, Hansgeorg; Wartzack, Sandro (DFX 2012: Proceedings of the 23rd Symposium Design for X, 2012)
Knowledge Based Engineering (KBE) offers a variety of methods and tools to design engineers in order to meet the challenges of modern product development processes. However, no universal and consistent approach exists to guide design engineers through the process of developing, implementing and running a KBE application. This led to the establishment of a working group within the VDI (Verein Deutscher Ingenieure). The members are from German companies and research institutes that deal with KBE applications, methods and tools. The aim is to develop a new VDI guideline that describes a methodical procedure for the implementation of a KBE application (referred to as KBE project). A unique approach is the definition of roles within a KBEproject that contribute in different manners depending on the actual project step. The most important role in this case is the knowledge engineer. The role of the knowledge engineer is described in this paper according to the VDI guideline and subsequently this description is compared with the result of a current industrial survey.
Keywords: knowledge based engineering; engineering standards; wissensbasiertes Konstruieren

Die Schmierstoffversorgung von Wälzlagern mittels loser Schmierringe - ein Ansatz zur Reduktion des Wartungsaufwands unter schwierigen Betriebsbedingungen - Müller, Matthias; Tremmel, Stephan (Dresdner Maschinenelemente Kolloquium, 2015)
Keywords: Wälzlager; Schmierung; Ringschmiersystem

Digitale Durchgängigkeit im Toleranzmanagement am Beispiel der ganzheitlichen Robustheitsbewertung in frühen Phasen - Horber, Dennis; Brand, Otto; Li, Jiahang; Götz, Stefan; Matthiesen, Sven; Wartzack, Sandro (Tagungsband der 5. Summer School Toleranzmanagement 2023, 2023)

Digital Engineering Methods in Practical Use during Mechatronic Design Processes - Gerschütz, Benjamin; Sauer, Christopher; Kormann, Andreas; Nicklas, Simon J.; Götz, Stefan; Roppel, Matthias; Tremmel, Stephan; Paetzold-Byhain, Kristin; Wartzack, Sandro (Designs, 2023)
This work aims to evaluate the current state of research on the use of artificial intelligence, deep learning, digitalization, and Data Mining in product development, mainly in the mechanical and mechatronic domain. These methods, collectively referred to as “digital engineering”, have the potential to disrupt the way products are developed and improve the efficiency of the product development process. However, their integration into current product development processes is not yet widespread. This work presents a novel consolidated view of the current state of research on digital engineering in product development by a literature review. This includes discussing the methods of digital engineering, introducing a product development process, and presenting results classified by their individual area of application. The work concludes with an evaluation of the literature analysis results and a discussion of future research potentials. <br
Keywords: digital engineering; product development; data mining; machine learning; data-driven methods; system design; system integration; implementation; validation

Digitaler zwilling oder digitales zwillingspärchen? - Wartzack, Sandro (Konstruktion, 2019)
CRIS-Team Scopus Importer:2021-04-20

Digitale Zwillinge und Digitale Zwillingspaare im Kontext des Digital Engineerings - Mögliche Anwendungen und Herausforderungen - Miehling, Jörg; Schleich, Benjamin; Wartzack, Sandro (Zeitschrift für wirtschaftlichen Fabrikbetrieb, 2020)
Neben der gezielten Nutzung von Daten und Informationen aus dem gesamten Produktlebenszyklus stellt die Integration des Nutzers und die Absicherung der Nutzer-Produkt-Interaktion im Digital Engineering eine wesentliche Herausforderung dar. Motiviert hierdurch beleuchtet der vorliegende Beitrag wesentliche Potentiale digitaler Zwillinge im Kontext des Digital Engineerings und stellt das Konzept des Digitalen Zwillingspaares als Möglichkeit der digitalen Einbindung des Nutzers in den Produktentstehungsprozess vor.<br

Digital Twin for Variation Management: A General Framework and Identification of Industrial Challenges Related to the Implementation - Wärmefjord, Kristina; Söderberg, Rikard; Schleich, Benjamin; Wang, Hua (Applied Sciences, 2020)
Digital twins have gained a lot of interest in recent years. This paper presents a survey among researchers and engineers with expertise in variation management confirming the interest of digital twins in this area. The survey shows, however, a gap between future research interest in academia and industry, identifying a larger need in industry. This indicates that there are some barriers in the industry to overcome before the benefits of a digital twin for variation management and geometry assurance can be fully capitalized on in an industrial context. To identify those barriers and challenges, an extensive interview study with engineers from eight different companies in the manufacturing sectors was accomplished. The analysis identifies industrial challenges in the areas of system-level, simulation working process, management issues, and education. One of the main challenges is to keep the 3D models fully updated, including keeping track of changes during the product development process and also feedback changes during full production to the development engineers. This is a part of what is called the digital thread, which is also addressed in this pape
Keywords: digital twin; manufacturing; tolerancing; geometry assurance; digital thread

Digital Twins - Definitions, Classes and Business Scenarios for Different Industry Sectors - Wilking, Fabian; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the Design Society, 2021)
Over the recent years, several attempts were made to define the concept of the Digital Twin and to create a generic view for utilizing it within the industry. Still, many industry sectors are not able to transfer a generic definition into their product portfolio, as Digital Twins differ from each other to the same degree as physical products differ from each other. Hence, it is crucial to enlarge the definition towards a classification and business scenarios which enable sector specific views on the concept of the Digital Twin and help SME to utilize the concept towards their products. Future engineers will have to design physical products besides a digital counterpart and therefore have to identify interdependencies between these two products during the development. This paper discusses a generic definition of a Digital Twin that can be applied throughout different sectors as well as a classification for Digital Twins to enable the implementation of the concept on several maturity levels regarding the constraints of the product portfolio. In addition, these classes are viewed in different business scenarios and an outlook is given to further increase the usability of Digital Twins within new industry sector

DTH-Fluid Hämmer für geothermische Bohrungen in (tiefen) Festgesteinen - Bartz, Marcel; Wittig, Volker; Lincke, Jan Dirk (BAUMA 2013 Geothermie-Forum, Workshop „Zukunftstechnologie Geothermie – Herausforderungen und Chancen“, 2013)

Dünnschichtsensoren zur Verschleißdetektion als Beitrag zur Auslegung intelligenter Werkzeuge – eine Machbarkeitsstudie - Weikert, Tim; Tremmel, Stephan (4. Workshop Blechmassivumformung: Umformtechnische Herstellung von komplexen Funktionsbauteilen mit Nebenformelementen aus Feinblechen, 2020)
Die Herstellung kompliziert geformter Blechbauteile in Prozessen der Blechmassivumformung (BMU) ist zuweilen nur durch lokal angepasste Reibungsbedingungen zwischen Werkzeug und Werkstück möglich. Einen bedeutenden Beitrag hierzu leisten Schichten aus amorphem Kohlenstoff (Diamond-Like Carbon, DLC), die eine gezielte Einstellung der Reibung in der Wirkfuge zur Steuerung des Materialflusses bei gleichzeitiger Verschleißreduktion am Werkzeug ermöglichen. Um den Verschleißzustand DLC-beschichteter Werkzeuge überwachen zu können, werden in dieser Machbarkeitsstudie kohlenstoffbasierte Schichten vorgestellt, deren Verschleiß durch einen ansteigenden elektrischen Widerstand detektierbar ist. Diese sensorischen Schichten bestehen im Wesentlichen aus niederohmigen Schichtlagen aus Chrom oder Wolframkarbid und hochohmigen Lagen aus siliziumoxiddotiertem amorphen Kohlenstoff. In wiederholten Ritztests konnte Schichtverschleiß am deutlichsten in chromhaltigen Sensorschichten detektiert werden. Kurzschlüsse zum metallischen Substrat erforderten eine ausreichende Dicke der hochohmigen Schichtlage für eine zuverlässige Verschleißdetektion. Es konnte herausgestellt werden, dass sich das vorteilhafte tribologische Verhalten kohlenstoffbasierter Schichten um eine sensorische Funktion zur Verschleißerkennung erweitern lässt, die eine individuelle Standzeit DLC-beschichteter Werkzeuge erlaub
Keywords: Verschleiß; Sensor; kohlenstoffbasierte Schicht

Durchgängige Rechnerunterstützung in der Produktentwicklung aufgrund des Einsatzes von semantisch hochwertiger Features - Wartzack, Sandro; Meerkamm, Harald (Konstruktion, 2000)
UnivIS-Import:2015-03-09:Pub.2000.tech.FT.FT-KLMEFK.durchg

Durchgängiges Toleranzmanagement aus Sicht des Lehrstuhls für Konstruktionstechnik - Wartzack, Sandro; Schleich, Benjamin; Heling, Björn; Götz, Stefan; Hallmann, Martin; Schächtl, Paul; Franz, Michael; Kramer, Vincent (Summer School Toleranzmanagement - Beiträge zur 4. Summer School - September 2020, 2020)

Durchgängige Systemmodellierung - Integration von Zielen in technische Systemmodelle im Kontext des Anforderungsmanagements - Horber, Dennis; Wilking, Fabian; Schleich, Benjamin; Wartzack, Sandro (Stuttgarter Symposium für Produktentwicklung SSP 2021, 2021)
Durch die steigende Komplexität technischer Konsumentenprodukte beschäftigen sich immer mehr Unternehmen mit Ansätzen, um diese Komplexität greifbarer zu machen. Ein Ansatz dafür ist das Model-Based Systems Engineering (MBSE). Ein zentrales Element dieses Ansatzes ist die Verwendung von Systemmodellen, die zur Beschreibung von Struktur und Verhalten des Systems dienen. Anforderungen lassen sich somit unmittelbar mit Systemelementen verbinden und verifizieren. Die im entwicklungsmethodischen Vorgehen oft vernachlässigten Ziele, die den Anforderungen hierarchisch übergeordnet sind, finden aber auch in diesen Modellen noch keine Anwendung. Dieser Beitrag beschäftigt sich damit, inwiefern sich Ziele konsistent in technische Systemmodelle integrieren lassen, sodass eine durchgängige Modellierung von den Zielen bis hin zu den einzelnen Elementen ermöglicht wird. Dabei werden bereits bestehende Möglichkeiten, hier beispielhaft in der System Modelling Language (SysML), um Systemelemente und Verbindungen ergänzt, um eine konsistente Integration von Zielen gewährleisten zu können und die Syntax der Notationen nicht erheblich zu beeinflussen.<br
Keywords: Model-Based Systems Engineering; MBSE; Systemmodell; Zielmodellierung; Anforderungsmanagement

Dynamics simulation of rolling element bearings considering elastohydrodynamic cage contacts - Seiler, Katrin; Hahn, Bodo; Plogmann, Michael; Tremmel, Stephan; Graf-Goller, Oliver; Wartzack, Sandro (Bearing World, 2016)
Keywords: Hydrodynamik; Elastohydrodynamik; Käfigelastizität; Wälzlager

Dynamics simulation of rolling element bearings considering elastohydrodynamic cage contacts - Seiler, Katrin; Tremmel, Stephan; Wartzack, Sandro; Hahn, Bodo; Plogmann, Michael; Graf-Goller, Oliver (Bearing World Journal, 2016)
Rolling bearings that run under high centripetal acceleration show increased friction in their cage contacts. Hence, the hydrodynamics as well as the deformation of the cage have to be taken into consideration in rolling element bearing dynamics simulations. This paper shows how to consider a full-elastically modelled cage in an elastic dynamics simulation for rolling element bearings to improve the accuracy of simulation results (esp. relating to friction torque). The deformed contact geometry is reconstructed from the cage’s nodes through cubic splines. After that the distance between the deformed cage geometry and the outer ring is calculated, which is considered as the lubrication film thickness. Finally, the contact pressure is calculated depending on the lubrication film thickness by using the short journal bearing theory. The contact calculation is compared to the elastic multi-body dynamics simulation program AVL ExciteTM. Furthermore, the simulation results considering the elastically modelled cage are evaluated to simulation results of a rigidly modelled cage using the rolling element bearings multi-body dynamics simulation program Caba3D. It can be seen that there is a significant influence on the pressure distribution and the friction torque if a rigidly modelled or a full-elastically modelled cage is utilized. The hydrodynamics and the cage’s elasticity should not be neglected in rolling bearing dynamics simulations for bearings that run under high centripetal accelerations.
Keywords: Simulation; Wälzlager; Elastohydrodynamik; Dynamik; Mehrkörpersimulation; MKS

Early Robust Design—Its Effect on Parameter and Tolerance Optimization - Götz, Stefan; Roth, Martin; Schleich, Benjamin (Applied Sciences, 2021)
The development of complex products with high quality in dynamic markets requires appropriate robust design and tolerancing workflows supporting the entire product development process. Despite the large number of methods and tools available for designers and tolerance engineers, there are hardly any consistent approaches that are applicable throughout all development stages. This is mainly due to the break between the primarily qualitative approaches for the concept stage and the quantitative parameter and tolerance design activities in subsequent stages. Motivated by this, this paper bridges the gap between these two different views by contrasting the used terminology and methods. Moreover, it studies the effects of early robust design decisions with a focus on Suh’s Axiomatic Design axioms on later parameter and tolerance optimization. Since most robust design activities in concept design can be ascribed to these axioms, this allows reliable statements about the specific benefits of early robust design decisions on the entire process considering variation in product development for the first time. The presented effects on the optimization of nominal design parameters and their tolerance values are shown by means of a case study based on ski bindings.
Keywords: robust design; parameter optimization; tolerance optimization; early design stages; axiomatic design

Early Tolerance Management and Robust Design - Götz, Stefan (Research in Tolerancing, 2024)
Tolerance management activities, such as specification, allocation, analysis, and synthesis, are commonly assigned to the late stages in product development when the product’s geometry is already fixed. However, inspired by the robust design philosophy, an early consideration of potential variations along the whole product development process bears great potential for an efficient tolerance management, since it allows easy design adaptions without the need for tight tolerances to fulfill the product requirements. Nevertheless, the lack of specific approaches and the missing geometry information, which is usually the basis for the application of established tolerance management methods, currently prevents the early realization and therefore calls for new methods. Thus, this article provides a framework for early consideration of variations by linking aspects from tolerance management, robust design, and quality management and its close integration into the product development process. This includes a structured robustness evaluation of principle solutions, a computer-aided robustness synthesis of concepts, and the automated tolerance specification and analysis of preliminary CAD designs. Thus, it contributes to shorter development times by automation and avoiding extensive iterations and provides a robust and reliable basis for the established tolerance management activities at the end of product developmen

Edge Pressures Obtained Using FEM and Half-Space: A Study of Truncated Contact Ellipses - Jüttner, Michael; Bartz, Marcel; Tremmel, Stephan; Correns, Martin; Wartzack, Sandro (Lubricants, 2022)
In rolling or gear contacts, truncation of the contact ellipse can occur, for example, when an undercut extends into the contact area. For an elastic calculation approach, the edge constitutes a mathematical singularity, which is revealed by a theoretically infinitely high pressure peak. However, when elastic–plastic material behavior is taken into account, the pressure peak is limited by local hardening and yielding of the material, leading to plastic deformations. As a result, those calculations are rather challenging and the results partly unexpected due to the discontinuity contained in the geometry. Nevertheless, to the authors’ knowledge, hardly any published studies exist on elastic–plastic simulations of truncated contact ellipses. Therefore, a numerical study concerning the contact of a rigid ball with an elastic–plastic plane is presented. Due to an undercut in the plane, a quarter of the theoretical Hertzian contact ellipse is cut off. The aim of the study is to investigate the influence of the undercut angle on the pressure distribution and the elastic and plastic deformation at the edge. The use of FEM shows that the undercut angle has a significant effect on the characteristics of the contact. The results obtained using FEM are then used as a reference for comparison with a semi-analytical method (SAM). It is shown that the SAM, based on the half-space, provides comparable results only for very small undercut angles.<br
Keywords: truncated contact; elastic-plastic; finite element method; semi-analytical method; undercut; edge pressure

Editorial: Human digital twins for medical and product engineering - Miehling, Jörg; Choisne, Julie; Koelewijn, Anne (Frontiers in Bioengineering and Biotechnology, 2024)
Keywords: biomechanics; personalized musculoskeletal modelling and simulation; human-technology interaction; sensorization; state estimation

Educational returns over the life course - Gross, Christiane; Jobst, Andreas; Jungbauer-Gans, Monika; Schwarze, Johannes (Zeitschrift für Erziehungswissenschaft, 2011)
Säule 5 des Nationalen Bildungspanels erfasst unterschiedliche Bildungsrenditen im Lebensverlauf. Das Längsschnittdesign ermöglicht die Untersuchung komplexer und dynamischer Interaktionsprozesse, in deren Rahmen Qualifikationen, Kompetenzen und Bildungszertifikate in ökonomische und nichtökonomische Renditen umgewandelt werden. In diesem Kapitel werden die zentralen theoretischen Konstrukte zur Analyse von Bildungsrenditen vorgestellt und ihre Implementierung im Nationalen Bildungspanel beschrieben. Wir diskutieren ökonomische Bildungsrenditen wie Einkommen und weitere Arbeitsmarkterträge mit einem Schwerpunkt auf Einkommenserwartungen als innovatives Konzept. Der Begriff der nichtökonomischen Bildungsrenditen subsumiert verbesserte Gesundheit, höheres subjektives Wohlbefinden, geringere Kriminalitätsneigung, erhöhte soziale und politische Partizipation und Auswirkungen auf den Prozess der Familienbildung. Bildungsrenditen in Form von Gesundheit und subjektiven Wohlbefinden sind über den ganzen Lebensverlauf – vom Kindergarten bis zum Erwachsenenalter – von Bedeutung, während Bildungsrenditen in Form von Kriminalitätsneigung und politischer Partizipation erst in der späten Jugendphase verstärkt auftreten. Um Kausalbeziehungen zu identifizieren, müssen gravierende Verzerrungen bei der Schätzung von Bildungsrenditen vermieden werden. Eine Quelle verzerrter Schätzer liegt in der fehlenden Berücksichtigung finanzieller Restriktionen des elterlichen Haushalts. Daher implementiert Säule 5 diverse Konstrukte zur Kontrolle der ökonomischen Haushaltssituation wie etwa Haushaltseinkommen und Vermögen.
WiSo-Import:2015-03-26:3373
Keywords: Bildung; Panelstudie; Renditen; Einkommen; Gesundheit

Effective usage of 2D MXene nanosheets as solid lubricant – Influence of contact pressure and relative humidity - Marian, Max; Song, Gui Cheng; Wang, Bo; Fuenzalida, Victor M.; Krauß, Sebastian; Merle, Benoit; Tremmel, Stephan; Wartzack, Sandro; Yu, Jinhong; Rosenkranz, Andreas (Applied Surface Science, 2020)
Newly emerging Ti3C2Tx–nanosheets (MXenes) have attracted considerable attention in energy storage, catalysis and, more recently, tribology. MXene nanosheets are characterized by a weakly-bonded multi-layered structure with self-lubricating ability, making them a suitable candidate for solid lubrication. This contribution aims at addressing for the first time their application in higher loaded steel/steel dry sliding contacts by investigating the influence of contact pressure and relative humidity on friction and wear performance. Compared to the uncoated reference, a 2.3-fold friction reduction and a 2.7-fold reduction of the wear volume were verified for MXene-coated specimens for moderate contact pressures and low relative humidity. This was due to the in-situ formation of a compacted tribo-film consisting of densified Ti3C2Tx–nanosheets. In contrast, too high pressures induced a partial rupture of the wear-protecting tribo-layer, thus reducing its beneficial effects. Additionally, no beneficial effects regarding friction and/or wear were found at higher relative humidities, which was correlated with the expansion of the basal spacings. Therefore, this study summarizes favorable operating conditions for MXene nanosheets when used as solid lubricant to improve friction and/or wear thus making them excellent candidates for advanced, next-generation solid lubricants.<br
Keywords: MXene-nanosheets; Contact pressure; Relative humidity; Friction reduction; Wear reduction

Effect of model parameters on finite element analysis of micromotions in implant dentistry - Winter, Werner; Klein, Daniel; Karl, Matthias (The Journal of oral implantology, 2013)
Micromotion between dental implant and bony socket may occur in immediate-loading scenarios. Excessive micromotion surpassing an estimated threshold of approximately 150 μm may result in fibrous encapsulation instead of osseointegration of the implant. As finite element analysis (FEA) has been applied in this field, it was the aim of this study to evaluate the effect of implant-related variables and modeling parameters on simulating micromotion phenomena. Three-dimensional FEA models representing a dental implant within a bony socket were constructed and used for evaluating micromotion (global displacement) and stress transfer (von Mises equivalent stress) at the implant-bone interface when static loads were applied. A parametric study was conducted altering implant geometry (cylinder, screw), direction of loading (axial, horizontal), healing status (immediate implant, osseointegrated implant), and contact type between implant and bone (friction free, friction, rigid). Adding threads to a cylindrically shaped implant as well as changing the contact type between implant and bone from friction free to rigid led to a reduction of implant displacement. On the other hand, reducing the elastic modulus of bone for simulating an immediate implant caused a substantial increase in displacement of the implant. Altering the direction of loading from axial to horizontal caused a change in loading patterns from uniform loading surrounding the whole implant to localized loading in the cervical area. Implant-related and bone-related factors determine the degree of micromotion of a dental implant during the healing phase, which should be considered when choosing a loading protocol.
UnivIS-Import:2015-03-09:Pub.2012.tech.FT.FT-TM.effect
Keywords: Simulation; Implantologie

Effect of picosecond laser based modifications of amorphous carbon coatings on lubricant-free tribological systems - Häfner, Tom; Heberle, Johannes; Hautmann, Hubert; Zhao, Rong; Tenner, Jennifer; Tremmel, Stephan; Merklein, Marion; Schmidt, Michael (Journal of Laser Micro Nanoengineering, 2017)

Effects of deposition parameters on hardness and lubrication properties of thin MoS2 films - Vierneusel, Bernd; Tremmel, Stephan; Wartzack, Sandro (Materialwissenschaft und Werkstofftechnik, 2012)
UnivIS-Import:2015-03-09:Pub.2012.tech.FT.FT-KLMEFK.effect

Effects of Nitrogen Modification of Porous PVD–MoS2 Coatings on the Tribological Behavior under Rolling–Sliding Conditions in Vacuum - Seynstahl, Armin; Polzer, Markus; Bartz, Marcel; Wartzack, Sandro; Tremmel, Stephan (Lubricants, 2023)
In order to improve the tribological performance of PVD–MoS2 coatings, which are frequently used as a solid lubricant for operating in challenging environments, e.g., in a vacuum, they can be modified with nitrogen. This work evaluates the tribological behavior and a possible compaction occurring during the initial tribological load in the rolling contact for pure and nitrogen-modified PVD–MoS2 coatings in a vacuum. Short-running tests (1000 cycles) of coated steel discs paired with uncoated steel discs made from 100Cr6 (1.3505, AISI 52100) were conducted on a two-disc tribometer. The slide-to-roll ratio of 10.5% was kept constant, while the load was varied in two steps from 1.1 GPa to 1.6 GPa. Subsequently, a comparison was made between the worn and the pristine coatings by means of nanoindentation and an optical analysis of the wear track. The formation of a load-bearing solid lubrication was achieved for both MoS2-variants. The main differences affected the material transfer and wear mechanisms. The worn coatings reached a similar wear coefficient of 4 × 10−6 mm3N−1m−1 and a possible compaction of the coatings was found, indicated through an increased indentation hardness (for MoS2 1158% and MoS2:N 96% at a 1.1 GPa load). The assumed tribological mechanism changed with nitrogen modification, but scales with increasing load. The nitrogen-modified MoS2 coating showed less compaction than pure MoS2, while the frictional behavior was improved by a 17°% reduction of the coefficient of friction. <br
Keywords: MoS2; tribology; vacuum; solid lubrication; transfer layer; two-disc

Effects of Ply Misalignment in Material Characterization of Composite Laminates - Franz, Michael; Radjef, Racim; Eisenbart, Boris; Wartzack, Sandro (Fibers, 2024)
Carbon fiber reinforced plastic (CFRP) parts find a rising number of applications as structural components. Therefore, new manufacturing technologies are developed, enabling high volume production of such parts. With those higher volumes, variation management during product design becomes more critical. While manufacturing variations in CFRP materials occur on different scales, detecting and considering those on the meso (ply) scale becomes more important. Thus, the question arises whether such variations can be detected with standardized testing methods. In this study, artificial fiber misalignment has been introduced into the outer plies of standardized tensile specimens to explore the influence of such variations on the mechanical properties. A simulation model was developed to identify these variations and the test results were used to calibrate and optimize the material parameters of the simulation model. The effects of the artificially induced variation were distinguishable in the test data as well as in the simulation models. Furthermore, the simulation models showed good agreement with the experimental data, which leads to the conclusion that the utilized measuring techniques are well suited to characterize the fiber misalignment. The developed simulation models can be used to investigate the effects of fiber misalignment within the product development process without the need for physical testing.
CRIS-Team Scopus Importer:2025-02-04
Keywords: CFRP; material characterization; mechanical properties; ply angles; variation analysis

Efficiency improvement in automobile bucket tappet/camshaft contacts by DLC coatings – Influence of engine oil, temperature and camshaft speed - Dobrenizki, Ladislaus; Tremmel, Stephan; Wartzack, Sandro; Hoffmann, Dennis; Brögelmann, Tobias; Bobzin, Kirsten; Bagcivan, Nazlim; Musayev, Yashar; Hosenfeldt, Tim (Surface & Coatings Technology, 2016)
With the aim to fulfill legal regulations concerning energy efficiency and greenhouse gas emissions, diamond-like carbon (DLC) coatings are increasingly used on highly stressed components of internal combustion engines to reduce friction and prolong component lifetime. The valve train is one of a key system of the combustion engine considerably contributing to frictional losses, especially under boundary and mixed lubrication conditions at lower crankshaft speeds. In this regard, the tribological contact bucket tappet/camshaft offers high potential for friction reduction but imposes high demands on DLC coatings due to highly complex kinematics and repetitive loads depending on the cam contours and the camshaft angle and speed. The aim of this work was to analyze the influence of DLC coatings on the frictional and wear behavior within the contact bucket tappet/camshaft. This tribological contact was analyzed in a one tappet/one cam friction test-rig using series-production tappets, cams and valve springs ensuring high transferability of the results into the real application. Two amorphous hydrogen containing carbon based coatings were deposited on series-production bucket tappets. The zirconium based DLC coating a-C:H/ZrCg was compared to a DLC coating system a-C:H:X deposited under industrial conditions. One mineral motor oil of SAE viscosity grade 0W20 and one synthetic motor oil polyalphaolefin (PAO) of SAE viscosity grade 5W30 formulated with different additive packages containing the anti-wear (AW)/extreme pressure (EP) additive zinc dialkyl dithiophosphate (ZDDP) and the friction modifier (FM) additives molybdenum dialkyl dithiocarbamate (MoDTC) and glycerol monooleate (GMO) were used in the test-rig. Special attention was paid to the interactions of the additive packages in the low viscosity oils with the functional surfaces of the a-C:H:ZrCg coated bucket tappets. The frictional behavior determined by time-resolved measurements of friction forces reveals that higher camshaft speeds led to increased lubrication film formation contributing to reduced frictional losses. Higher motor oil temperature resulted in temperature induced reduced viscosity of the motor oils leading to higher frictional losses. The DLC coatings a-C:H:ZrCg and a-C:H:X caused significant reduction of frictional losses under the operating conditions in the test-rig. The a-C:H:ZrCg coated bucket tappets caused higher frictional losses than uncoated bucket tappets at low camshaft in boundary friction conditions. Friction reduction at all operating points was ensured by a-C:H:X regardless of camshaft speed, motor oil temperature and the choice of motor base oil and additive package proving the great potential for application on components under challenging lubricating and loading conditions. The wear of the uncoated and a-C:H:ZrCg coated functional surfaces was analyzed by means of confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The a-C:H:ZrCg coating contributed to wear protection in the highly loaded tribological contact despite the different lubricating and loading conditions regardless of the base oil and additive packages. The a-C:H:X coating revealed similar favorable behavior. Comprehensive surface sensitive analysis of the uncoated and a-C:H:ZrCg coated bucket tappets by means of Raman spectroscopy and XPS indicated that no tribo-chemical reaction layer was formed from the motor oil and the additive packages on a-C:H:ZrCg coated bucket tappets under the operating conditions. Moreover, the combination of additives ZDDP and GMO in PAO appears to be disadvantageous in terms of reaction layer formation since no tribo-chemical reaction layer was found on uncoated steel bucket tappets after tribological tests in contrast to the mineral oil containing ZDDP and MoDTC.
Keywords: Valve train; Bucket tappet/camshaft contact; Friction test-rig; DLC PVD coating; Friction; Wear; Motor oil; Additives; ZDDP; MoDTC; GMO; Tribo-chemical reaction layer; Raman analysis; XPS analysis

Efficient Computation of Spatial Truss Structures for Design Optimization Approaches Using Tube-Shaped Thin-Walled Composite Beams - Jäger, Michael; Wartzack, Sandro (Proceedings of the Munich Symposium on Lightweight Design 2021, 2022)
Spatial truss structures are a stiff, economical, and effective lightweight design method, especially when using composites instead of isotropic materials for the struts. An efficient computation of these structures is crucial for optimization approaches during the product design process. The most common method for computing spatial truss structures relies on hinged connections with tension/compression-only struts, which ignores the bending and coupling effects of composite beams. However, especially when using asymmetric laminates, these effects are no longer neglectable. Within commercial finite element tools, the computation of large truss structures - which include these effects - is a very time-consuming process. Particularly for slender, thin-walled beams a large number of solid/shell elements is required. In this paper, an analytical solution of the stiffness matrix for a tube-shaped thin-walled composite beam is provided. It is based on the classical laminate plate theory and Timoshenko’s exact solutin including shear deformation and coupling effects. By using three-dimensional exact Timoshenko beam elements, the number of degrees of freedom can be reduced significantly while coupling effects are maintained. This results in a remarkably lower computation time especially needed for topology optimization. The results are compared to a commercial finite element tool using both solid and shell elements.<br
Keywords: Lightweight design; Spatial truss structures; Structural optimization; Thin-walled composite beams; Timoshenko beam

Effiziente Geometrierekonstruktion nach Topologieoptimierung eines Motorhalters - Mayer, Johannes; Sippl, Christian; Hufnagel, Thomas; Wartzack, Sandro (Konstruktion, 2024)
Topologieoptimierung (TO) kann Ausgangspunkt für effizienten Materialeinsatz und hochperformante Leichtbaukomponenten sein. Hierfür ist nach der TO eine Rekonstruktion der Geometrie in einem eigenen Prozessschritt nötig. Insbesondere wenn das Optimierungsergebnis nicht als abstraktes Oberflächenmodell, sondern als parametrische Computer-Aided-Design-(CAD)-Geometrie in den Entwicklungsprozess zurückgeführt wird, ist die Rekonstruktion arbeits- und zeitintensiv. Dieser Artikel beschreibt die Anwendung einer neuen, featurebasierten Forschungsmethode an einem Motorhalter von MAN. Statt aufwändiger Gestaltungszyklen unterstützt die Methode durch Automatisierung und Parametri
Keywords: Topologieoptimierung; Geometrierückführung; Computational Design; Generatives Design; Computer Aided Design

Effiziente Geometrierekonstruktion nach Topologieoptimierung eines Motorhalters - Mayer, Johannes; Sippl, Christian; Hufnagel, Thomas; Wartzack, Sandro (Konstruktion, 2024)
Topology optimization (TO) can be the starting point for efficient material use and high-performance lightweight components. However, a reconstruction of the geometry in a separate process step is necessary after TO. Especially if the optimization result is not considered in the development process as an abstract surface model but as parametric computer-aided design (CAD) geometry, the reconstruction is laborand time-intensive. In contrast, this article discusses the application of a new feature-based research method to an engine bracket from MAN. Instead of elaborate design cycles, the method supports automation and parametrics.
CRIS-Team Scopus Importer:2024-11-22

Effiziente, prozessorientierte Konformitätsbewertung bei Toleranzsimulationen auf Basis von Klassifikationsmodellen - Schächtl, Paul; Roth, Martin; Götz, Stefan; Schleich, Benjamin; Wartzack, Sandro (Tagungsband der 5. Summer School Toleranzmanagement 2023, 2023)

Effiziente, strukturierte Auslegung beanspruchungsgerechter Faserverbundbauteile - Völkl, Harald; Wartzack, Sandro (Tagungsband LLC 2019, Leichtbau in Forschung und industrieller Anwendung von der Nano- bis zur Makroebene, 2019)
Effiziente CAE-Auslegungsansätze helfen, den steigenden Anforderungen an Qualität, Zeit- und Kostendruck zu begegnen. Insbesondere die komplizierte Auslegung von Faserverbundbauteilen erfordert adäquate Unterstützung. Ein neu entwickelter Ansatz für diesen Zweck wird vorgestellt und dessen Ergebnis anhand eines Schalensitzes mit konventionellen Laminaten vergliche

Ein Beitrag zur Auslegung beschichteter Bauteile unter zyklischer Beanspruchung im Wälz-Gleit-Kontakt - Tremmel, Stephan (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2010)
UnivIS-Import:2016-07-26:Pub.2010.tech.FT.FT-KLMEFK.einbei

Eine Näherungsmethode zur schnellen Simulation von mehrfach überrollten elasto-plastischen Kontakten in Wälzlagern - Jüttner, Michael; Wartzack, Sandro; Bartz, Marcel; Tremmel, Stephan; Correns, Martin (14. VDI-Fachtagung Gleit- und Wälzlagerungen 2021. Gestaltung - Berechnung - Einsatz, 2021)
Zur Bewertung von Pressungsspitzen in den Kontakten von Wälzlagern, die bei zum Lastfall unpassender Lagergeometrie oder bei ungünstigen Betriebsbedingungen auftreten können, ist die Berücksichtigung von elasto-plastischem Materialverhalten notwendig, sobald die aus der Pressung resultierenden Spannungen lokal die Fließgrenze des Werkstoffes überschreiten. Eine gegebenenfalls fortschreitende Plastifizierung und die daraus folgende Veränderung der Kontaktgeometrie bei mehrfacher Überrollung lässt sich somit erfassen. Die Simulation von mehrfach überrollten elasto-plastischen Kontakten erfolgt in der Regel mit einem transienten Ansatz, was mit herkömmlichen Verfahren sehr zeitaufwändig ist. Um die Bewertung von Pressungsspitzen in den Zeitrahmen der etablierten Lagerauslegung eingliedern zu können wird in diesem Beitrag, ausgehend von einer transienten Simulation einer Mehrfachüberrollung, eine schnelle Näherungsmethode vorgestellt. Als Beispiel wird der Kontakt von Kugel und Innenringlaufbahn eines Rillenkugellagers untersucht und es werden die Ergebnisse der Näherungsmethode diskutiert.<br
Keywords: elasto-plastischer Kontakt; Mehrfachüberrollung; Näherungsmethode

Eine Untersuchung mechanisch gealterter kurzfaserverstärkter Thermoplaste unter hochdynamischen Lasten - Witzgall, Christian; Wartzack, Sandro (Design for X - Beiträge zum 27. DfX-Symposium, 2016)

Einfluss der Mikrostruktur gesputterter Molybdändisulfid-(MoS2) Schichten auf die Lagergebrauchsdauer im Trockenlauf - Vierneusel, Bernd; Tremmel, Stephan; Wartzack, Sandro (11. VDI-Fachtagung Gleit- und Wälzlagerungen 2015: Gestaltung, Berechnung, Einsatz (VDI-Berichte 2257), 2015)
UnivIS-Import:2015-10-26:Pub.2015.tech.FT.FT-KLMEFK.einflu_6

Einfluss der Schmierstoffhydrodynamik in der Käfigführung auf die Wälzlagerreibung und -kinematik - Seiler, Katrin; Tremmel, Stephan; Wartzack, Sandro; Hahn, Bodo; Graf-Goller, Oliver (VDI-Berichte 2257, 2015)
Werden Wälzlager hohen Zentripetalbeschleunigungen ausgesetzt kann die Reibung an den Käfigkontakten sehr stark ansteigen. In solchen Anwendungsfällen ist in der Wälzlagermehrkörpersimulation die Schmierstoffhydrodynamik in den Käfigkontakten zu berücksichtigen. Hierbei reicht es im Fall des Kontakts zwischen Käfig und Außenring nicht aus, ausschließlich den hydrodynamischen Kontakt an den Käfigstirnringen zu berücksichtigen. Um die Käfigführung realistisch abbilden zu können ist zusätzlich der Kontakt an den Käfigstegen, an denen ebenfalls hydrodynamische Effekte auftreten, zu berücksichtigen. Der vorliegende Beitrag stellt analytische und validierte Berechnungsmodelle für die Berücksichtigung der Hydrodynamik an den Käfigstegen vor. Rolling bearings that run under high centripetal acceleration show high friction at their cage contacts. That is why the hydrodynamic lubrication has to be taken into consideration in a rolling bearing multi-body dynamic simulation. In case of the contact between cage and outer ring the hydrodynamic has to be calculated for the cage’s bars and sideway rings. This paper presents an analytical and validated hydrodynamic model for the use in a multi-body dynamic simulation and shows simulation results of a piston rod needle bearing.
UnivIS-Import:2015-10-26:Pub.2015.tech.FT.FT-KLMEFK.einflu
Keywords: Wälzlager; MKS; Tribologie; Hydrodynamik

Einfluss des tribochemischen Schichtaufbaus auf die Ausbildung elektrisch induzierter Wälzlagerschäden - Pohrer, Benjamin; Zürcher, Manuel; Tremmel, Stephan; Wartzack, Sandro; Schlücker, Eberhard (Tribologie und Schmierungstechnik, 2016)
Gleichstrombelastete Wälzlager zeigen bereits bei sehr geringen Stromdichten unter bestimmten Bedingungen Schädigungen der Laufbahnoberflächen oder Veränderungen des Gefüges. Erste Untersuchungen deuten darauf hin, dass diese Phänomene im Zusammenhang mit der Ausbildung isolierend wirkender, tribochemischer Schichten im Wälzkontakt stehen. Dieser Schichtaufbau kann anhand der elektrischen Eigenschaften des Prüflagers und einer begleitenden in-situ-IR-Analyse des Schmierstoffs während des Betries nachvollzogen werden. Under specific conditions, rolling bearings exposed to direct currents show surface demages on the raceway or microstructural changes even at very low current densities. Initial investigations indicate that these phenomena are related to the formation of insulating tribochemical layers in the rolling contact. These surface processes can be understood with reference to the electrical properties of the bearing and an accompanying in-situ IR analysis of the lubricant.
Keywords: IR-Spektroskopie; Schmierstoffe; Additive; Wälzlagerschäden; Tribochemie; Schichtaufbau; IR-Spectroscopy; Lubricants; Additives; Rolling bearing failures; Tribochemistry; Tribolayers; White Structure Flaking

Einfluss des tribochemischen Schichtaufbaus auf die Ausbildung elektrisch induzierter Wälzlagerschäden - Pohrer, Benjamin; Zürcher, Manuel; Tremmel, Stephan; Wartzack, Sandro; Schlücker, Eberhard (56. Tribologie-Fachtagung. Reibung, Schmierung und Verschleiß. Band II, 2016)
Gleichstrombelastete Wälzlager zeigen bereits bei sehr geringen Stromdichten unter bestimmten Bedingungen Schädigungen der Laufbahnoberflächen oder Veränderungen des Gefüges. Erste Untersuchungen deuten darauf hin, dass diese Phänomene im Zusammenhang mit der Ausbildung isolierend wirkender, tribochemischer Schichten im Wälzkontakt stehen. Dieser Schichtaufbau kann anhand der elektrischen Eigenschaften des Prüflagers und einer begleitenden in-situ IR-Analyse des Schmierstoffs während des Betriebs nachvollzogen werden.     Under specific conditions, rolling bearings exposed to direct currents show surface damages on the raceway or microstructural changes even at very low current densities. Initial investigations indicate that these phenomena are related to the formation of insulating tribochemical layers in the rolling contact. These surface processes can be understood with reference to the electrical properties of the bearing and an accompanying insitu IR analysis of the lubricant.

Einfluss masseerhaltender Kavitationsmodelle bei der Simulation hydro- und elastohydrodynamischer Kontakte - Marian, Max; Weschta, Martin; Tremmel, Stephan; Wartzack, Sandro (Tribologie und Schmierungstechnik, 2017)
Numerische Simulationen können bei der Auslegung hydro- (HD) und elastohydrodynamischer (EHD) Kontakte in geschmierten tribologischen Systemen bereits in einer frühen Phase der Produktentwicklung helfen, fundierte Kenntnisse über vorliegende Beanspruchungen und Schmierungszustände zu erlangen. Die Eigenschaften der beteiligten Systempartner und die auftretenden Phänomene – unter anderem Kavitation – sind durch physikalische Modelle möglichst exakt zu repräsentieren, wohingegen Rechenzeiten gering gehalten werden sollen. Vor diesem Hintergrund wird ein effizienter Ansatz für ein masseerhaltendes Kavitationsmodell vorgestellt und dessen Einfluss auf die berechnete Verteilung von Druck und Schmierspalthöhe im Vergleich zu nicht-masseerhaltenden Alternativen anhand beispielhafter Fälle aufgezeig
Keywords: Elastohydrodynamik; Finite-Elemente; Hydrodynamik; Masseerhaltendes Kavitationsmodell; Mikrostrukturierte Oberflächen; Simulation

Einfluss masseerhaltender Kavitationsmodelle bei der Simulation hydro- und elastohydrodynamischer Kontakte - Marian, Max; Weschta, Martin; Tremmel, Stephan; Wartzack, Sandro (57. Tribologie-Fachtagung. Reibung, Schmierung und Verschleiß. Band I, 2016)
Numerische Simulationen können bei der Auslegung hydro- (HD) und elastohydrodynamischer (EHD) Kontakte in geschmierten tribologischen Systemen bereits in einer frühen Phase der Produktentwicklung helfen, fundierte Kenntnisse über vorliegende Beanspruchungen und Schmierungszustände zu erlangen. Die Eigenschaften der beteiligten Systempartner und die auftretenden Phänomene – unter anderem Kavitation – sind durch physikalische Modelle  möglichst exakt zu repräsentieren, wohingegen Rechenzeiten gering gehalten werden sollen. Vor diesem Hintergrund wird ein effizienter Ansatz für ein masseerhaltendes Kavitationsmodell vorgestellt und dessen Einfluss auf die berechnete Verteilung von Druck und Schmierspalthöhe im Vergleich zu nicht-masseerhaltenden Alternativen anhand beispielhafter Fälle aufgezeigt.
Keywords: Elastohydrodynamik; Finite-Elemente; Hydrodynamik; Masseerhaltendes Kavitationsmodell; Mikrostrukturierte Oberflächen; Simulation

Einfluss statistisch verteilter geometrischer Formabweichungen auf Reibmoment und Schwingungsanregung von Zylinderrollenlagern - Kramer, Vincent; Atalay, Onur; Koch, Oliver; Bartz, Marcel; Schleich, Benjamin; Wartzack, Sandro (63. Tribologie-Fachtagung, 2022)
Wälzlager ermöglichen eine kostengünstige und präzise Führung rotierender Bauelemente und kommen daher im gesamten Maschinenbau in großer Stückzahl zum Einsatz. Bei der Auslegung von Wälzlagerungen wird üblicherweise von idealen Geometrien von Lagern und Anschlusskonstruktion ausgegangen. Reale Bauteile weisen jedoch unvermeidlich Abweichungen von ihrer nominalen Gestalt auf. Diese können zu einer Veränderung der lagerinternen Kontakt- und Lastverhältnisse führen, was sich in der Folge auch auf das Betriebsverhalten des Lagers – wie etwa das entstehende Reibmoment oder das Schwingungsverhalten – auswirken kann. Durch Berücksichtigung dieser Effekte können die Ergebnisqualität bei der Auslegung von Wälzlagerungen verbessert sowie konstruktive Optimierungspotentiale aufgezeigt werden. Der vorliegende Beitrag stellt daher eine Methode zur Integration dieser geometrischen Nichtidealitäten bei der Auslegung von Zylinderrollenlagerungen vor. Die statistische Natur der in der Realität auftretenden Abweichungen wird dabei durch Auswertung einer Vielzahl zufällig generierter Einzelfälle (sog. Sampling) abgebildet. Hierzu erfolgt zunächst eine zufallsbasierte Erzeugung einer beliebigen Anzahl abweichungsbehafteter Lagergeometrien, welche anschließend statistisch evaluiert werden können. Für kritische Fälle kann dann in einer Mehrkörpersimulation (MKS) eine detaillierte Auswertung hinsichtlich Reibmoment und Schwingungsverhalten durchgeführt werden. Der Neuheitswert des vorgestellten Verfahrens besteht somit in der Berücksichtigung von in der Realität unvermeidlichen statistisch verteilten geometrischen Abweichungen bei der Auslegung von Wälzlagerungen. Die Vorgehensweise wird dabei im Rahmen des Beitrags anhand eines Beispiels erläuter
Keywords: Wälzlager; Zylinderrollenlager; Toleranzanalyse; Reibung; Schwingungen; Mehrkörpersimulation

Einfluss verschiedener Wahrscheinlichkeitsverteilungen bei der varianzbasierten Sensitivitätsuntersuchung - Heling, Björn (Summer School Toleranzmanagement Beiträge zur 1. Summer School September 2013, 2013)

Einfluss von Dotierungselementen in ta-C Beschichtungen auf Reibungs- und Verschleißeigenschaften im geschmierten Tribokontakt - Polzer, Markus; Bartz, Marcel; Schulz, Edgar; Procelewska, Joanna; Wartzack, Sandro (Tribologie-Fachtagung, 2021)
Tetraedrisch amorphe Kohlenstoffschichten (ta-C) werden bereits vielfach als reibungsarme, verschleißbeständige Funktionsschichten auf mechanisch beanspruchten Komponenten genutzt. In geschmierten Systemen kann es jedoch auf Grund der komplexen Wechselwirkung von Beschichtungssystem, Schmierstoffadditiven und Belastungskollektiv zu unvorhergesehenen Wechselwirkungen im Tribokontakt kommen. Die Wirkmechanismen dieser Wechselwirkungen beeinträchtigen im schlimmsten Fall die Lebensdauer oder die allgemeine Effizienz des vorliegenden Tribosystems und können allein durch eine Betrachtung der Dotierungselemente und den mechanischen Eigenschaften der Schichten nicht vorhergesagt werden. Um diese komplexen Wirkmechanismen besser verstehen zu können und um weitere Effizienz und Lebensdauer steigernde Effekte zu untersuchen, soll in diesem Beitrag der Einfluss unterschiedlicher Dotierungselemente im geschmierten Tribokontakt untersucht werden. Dafür werden, neben der Analyse der mechanischen und topographischen Eigenschaften, die verschiedenen dotierten ta-C Schichtsysteme mit einer undotierten ta-C Schicht verglichen. Durchgeführt werden die Untersuchungen an beschichteten Proben auf einem Tassenstößel-Reibungsprüfstand mit realen Motorkomponenten und auf einem Kugel-Scheibe-Tribometer. Bei dem verwendeten Schmierstoff handelt es sich um ein kommerziell standardisiertes, nicht additiviertes Öl. Ziel ist die Auswirkungen der Dotierungselemente auf das Reibungs- und Verschleißverhalten darzustellen und zu vergleichen.<br

Ein Klassifizierungssystem zur Anforderungssystematisierung - Horber, Dennis; Schleich, Benjamin; Wartzack, Sandro (Design for X. Beiträge zum 30. DfX-Symposium, 2019)
This paper presents a holistic approach to structure and classify requirements of the product life cycle systematically and make them accessible for the evaluation process. In a first analysis step, process models of selected literature are analyzed regarding classification and structuring of requirements as well as their derivation into evaluation criteria. In a subsequent synthesis step, the classification system is developed with a consistent consideration of the multi-criteria evaluation process. This approach therefore contributes to raise the awareness of an appropriate handling of requirements and to minimize forgotten requirements as well as evaluation criteria. As a result, costly iterations in the development process can be reduced sustainably by using the proposed approac
Keywords: requirement engineering; requirement classification; multi criteria decision making; product development

Ein Kommentar zum mehrachsigen Spannungszustand im reibungsfrei überrollten Kontakt elastischer Körper und zur Anwendung von Vergleichsspannungshypothesen - Jüttner, Michael; Tremmel, Stephan; Correns, Martin; Koch, Oliver; Wartzack, Sandro (61. Tribologie-Fachtagung 2020, 2020)
Zur Bewertung eines überrollten Kontaktes sind insbesondere Wissen über den inhomogenen mehrachsigen Spannungszustand sowie die Einschränkungen verfügbarer Vergleichsspannungshypothesen maßgeblich. Der Beitrag beleuchtet deshalb am Beispiel des reibungsfrei überrollten elastischen Hertzschen Kugel-Ebene-Kontaktes zunächst den mehrachsigen Spannungszustand, um daraus anschließend die Beanspruchungshistorie bei Überrollung abzuleiten. Abschließend werden anhand der Gestaltänderungsenergiehypothese die Chancen und Einschränkungen bei der Nutzung von Vergleichsspannungen aufgezeigt.
Keywords: Hertzscher Kontakt; überrollter Kontakt; mehrachsiger Spannungszustand; Festigkeitshypothese

Ein Kommentar zum mehrachsigen Spannungszustand im reibungsfrei überrollten Kontakt elastischer Körper und zur Anwendung von Vergleichsspannungshypothesen - Jüttner, Michael; Tremmel, Stephan; Correns, Martin; Koch, Oliver; Wartzack, Sandro (Tribologie und Schmierungstechnik, 2021)
Zur Bewertung der Tragfähigkeit eines überrollten Kontaktes sind insbesondere Wissen über den inhomogenen mehrachsigen Spannungszustand sowie die Einschränkungen verfügbarer Vergleichsspannungshypothesen maßgeblich. Der Beitrag beleuchtet deshalb am Beispiel des HERTZschen Kontaktes Kugel/Ebene zunächst den mehrachsigen Spannungszustand, um daraus anschließend die Beanspruchungshistorie bei reibungsfreier Überrollung abzuleiten. Abschließend werden anhand der Gestaltänderungsenergiehypothese die Chancen und Einschränkungen bei der Nutzung von Vergleichsspannungen aufgezeigt.<br
Keywords: Kontaktmechanik; HERTZscher Kontakt; Spannungsfeld; Hauptspannungsorientierung; von Mises-Spannung; contact mechanics; HERTZian contact; stress field; principal stress orientation; von Mises stress

Ein methodisches Framework für das prozessorientierte Toleranzmanagement - Schleich, Benjamin; Wartzack, Sandro (Stuttgarter Symposium für Produktentwicklung (SSP) 2013, 2013)
Aufgrund steigender Ansprüche an technische Produkte ist eine ganzheitliche Berücksichtigung aller qualitätsmindernden Faktoren, zu denen besonders geometrische Abweichungen zählen, bereits während der Produktentwicklung eine Voraussetzung für erfolgreiche Produkte. Während der Produktentwicklung müssen daher geometrische Toleranzen festgelegt werden um die Qualität und Funktion des Produktes sicherzustellen. Mit dem Ziel die Toleranzvergabe zu vereinfachen, wird ein methodisches Framework für die Integration von Abweichungsinformationen aus den verschiedenen Phasen des Produktlebenszyklus in Toleranzsimulationen entwickelt. Um virtuelle Absicherungsmethoden effizient zu integrieren, baut das Framework auf einer diskreten Geometrierepräsentation abweichungsbehafteter Bauteile auf. Durch die Integration von Informationen aus späteren Phasen des Produktlebenszyklus ergibt sich ein ganzheitliches Bild aller Prozessparameter, die Einfluss auf die Qualität des Produktes haben. Darauf aufbauend können durch die gezielte Wahl von Toleranzen ein gefordertes Qualitätsniveau sichergestellt und unnötig enge Toleranzen vermieden werden.
Keywords: Toleranzmanagement; Virtuelle Produktentwicklung; Oberflächenmodell

Ein ontologiebasierter Ansatz zur Wissensrepräsentation für die smarte Produktentwicklung - Sauer, Christopher; Kügler, Patricia; Kestel, Philipp; Graf, Michaela; Göbel, Kyra; Niessen, Cornelia; Schleich, Benjamin; Wartzack, Sandro (Tagungsband 16. Gemeinsames Kolloquium Konstruktionstechnik, 2018)
The amount of knowledge shared between or inside engineering design teams, often working in different engineering environments, needs to be increased. For instance, such knowledge refers to design-relevant manufacturing knowledge or methods for checking the properties and the behaviour of components using numerical simulations. An efficient knowledge exchange is essential. To support this new collaborative design approach, this contribution proposes an interface in engineering design, which provides all relevant knowledge to a design. It is based on the knowledge representation employing ontologies. The novelty of the presented approach can be found in using an ontology for the relevant engineering design knowledge and in the description of the whole ontology design process.<br
Keywords: Smart Engineering; Knowledge Management; Transparency; Ontologies

Einsatz analytisch beschreibbarer Geometrien zur Berechnung des Kontaktes zwischen Wälzkörper und Bord in Wälzlagersimulationen - Wirsching, Sven; Schwarz, Sebastian; Tremmel, Stephan (60. Tribologie-Fachtagung 2019, 2019)
A large number of different contact points exist in rolling bearings. The rolling elements interact with the raceway, with the cage or other rolling elements and with the rib or ribs. Depending on the load situation, all these contacts contribute differently to the frictional power, to the temperature increase and thus to the capacity of the bearing. High axial loads are carried by the ribs of roller bearings, as is the case, for example, with tapered roller bearings, but also with the new Angular Roller Unit (ARU) from Schaeffler. In these cases, the contact between the rolling element and the rib significantly influences the frictional power. For its calculation, a detailed description of the contact in bearing simulation tools is necessary. An improved friction calculation allows the specific development of more efficient rolling bearings. In existing programs for the dimensioning of bearings, the contact calculation between rolling element and rib is usually based on the theory of HERTZ, which is accurate only for some geometric pairings. Complex geometries of the contact partners, which are typically used to reduce friction between the rolling element and the rib, cannot be described with sufficient precision, leading to more or less large discrepancies in the calculation of deflections, contact zones and contact pressures compared to high-quality numerical calculations (for example finite element analysis). This also means that the frictional power is not calculated sufficiently accurately. For that reason, this paper presents a new, more accurate method for calculating the contact between the rolling element and the rib. The geometries of the two contact partners are described analytically and form a substitute geometry. By pressing this substitute geometry into a two-dimensional bedding according to the approach of WIN-KLER, the equilibrium of forces in contact is solved similarly to the work of POPOV, whereby the contact area and the resulting pressure distribution are calculated. The developed method is compared for different contact pairings with the finite element method. By comparing the contact area, -shape and -pressure, the potential and the limits of the new method are assessed.
Keywords: Contact; calculation and simulation methods; bearings

Einsatz von Data-Mining in modernen Produktentstehungsprozessen - Breitsprecher, Thilo; Kestel, Philipp; Küstner, Christof; Sprügel, Tobias; Wartzack, Sandro (Zeitschrift für wirtschaftlichen Fabrikbetrieb, 2015)
Das Arbeitsumfeld von Produktentwicklern und Konstrukteuren unterliegt einem ständigen Wandel. Die fortschreitende Globalisierung der Märkte, der steigenden Innovationsdruck und die erhöhten Individualität und Dynamik der einzelnen Absatzregionen, lassen die Anforderungen an Produkte sowie an Produktentstehungsprozesse immer differenzierter werden. Der Lehrstuhl für Konstruktionstechnik (KTmfk) der Friedrich-Alexander Universität Erlangen-Nürnberg (FAU) erforscht Data-Mining-Lösungen für die Produktentstehung, die den Unternehmen helfen mit dieser Entwicklung Schritt halten zu können.
Keywords: Industrie 4.0; Data Mining

Einsatz von Deep Learning zur ortsaufgelösten Beschreibung von Bauteileigenschaften - Sauer, Christopher; Küstner, Christof; Schleich, Benjamin; Wartzack, Sandro (Design for X. Beiträge zum 28. DfX-Symposium, 2017)
Within the Transregional Collaborative Research Centre 73 (SFB/TR 73) a self-learning engineering workbench (SLASSY) is being developed. SLASSY assists product developers in designing sheet-bulk metal formed (SBMF) parts by computing product properties based on given product and process characteristics. SLASSY enables product developers to evaluate the manufacturability of their current part design. For this, SLASSY uses data from manufacturing experts to create metamodels. Currently, it can handle product properties which apply for a whole part variant (on whole part level), for instance the minimum form filling degree. The further development of the SBMF manufacturing technology requires the consideration of the product properties in higher detail (on local level). This requires a higher data density, that is, data for each part variant and product property need to be acquired on every point of interest. Due to the increased amount of data, the currently used data mining algorithms in SLASSY for creating the metamodels cannot be reused. To face this challenge, deep learning algorithms are utilized which are good in processing big data. In this contribution, two approaches for the use of deep learning to compute product properties on local level are presented.
Keywords: product properties; deep learning; data mining; neural networks

Einsatz von gedruckten Sensoren zur Messung der Dehnung von Wälzlagern unter isolierten Randbedingungen - Halmos, Fabian; Jüttner, Michael; Bartz, Marcel; Ankenbrand, Markus; Häusler, Felix; Franke, Jörg; Wartzack, Sandro (WiGeP News, 2023)

Einsatz von Graphdatenbanken für das Produktdatenmanagement im Kontext von Industrie 4.0 - Sauer, Christopher; Schleich, Benjamin; Wartzack, Sandro (Entwickeln Entwerfen Erleben in Produktentwicklung und Design 2019, 2019)
Im Zuge der digitalen Transformation im Kontext von Industrie 4.0 tun sich eine Vielzahl neuer Datenquellen auf, die im Produktdatenmanagement berücksichtigt werden müssen. Kennzeichen dieser Datenquellen sind die zunehmende Heterogenität der Daten. Dieser Umstand führt zum Aufbau vieler einzelner neuer Silos, die abgeschottet von den restlichen Silos Daten speichern. Daneben führt eine Vielzahl neuer Autorensysteme zu einer gesteigerten Datenmenge, die nicht mehr in klassischen tabellenbasierten und rein-relationalen Datenbanksystemen sinnvoll erfasst werden können. Um an Informationen zu gelangen, sind oft komplizierte Abfragen nötig, die auf mehrere unterschiedliche Datenbanken zugreifen, um daraus wiederum relevante Informationen bereitzustellen. Dies schafft ungewollt eine Redundanz innerhalb des Produktdaten-managements, da nicht direkt mit den zugrundeliegenden Daten gearbeitet werden kann. Somit büßen rein-relationale Datenbanksysteme einen Großteil ihrer Vorteile ein. Um den oben genannten Problemen zu begegnen, können neue Ansätze aus dem Bereich der Linked Data für das Produktdatenmanagement herangezogen werden. Hierbei wird es in einem ersten Schritt möglich, heterogene Produktdaten, also Daten aus verschiedensten Quellen wie zum Beispiel CAD, Simulation, Qualitätssicherung und Einkauf miteinander zu verknüpfen. Dabei können auch Themen aus dem Umfeld von Industrie 4.0 aufgegriffen werden. So lassen sich zum Beispiel Felddaten aus Sensoren direkt integrieren und als Datenquelle bereitstellen. Durch diese Verknüpfung kann eine neue höherwertige Repräsentationsform für das Produktdatenmanagement geschaffen werden, die neben den reinen Daten und Metadaten auch die sinnvolle Verknüpfung der zugrundeliegenden Daten und Datenquellen enthält und so eine semantische höherwertige Repräsentation darstellt. Das Produktdatenmanagement entwickelt sich so von der reinen Ablage in teilweise kompliziert strukturierten Datenbanken hin zu einem verknüpften System, das Produktdaten beliebiger Repräsentationsform in einem ersten Schritt erhalten und im nächsten Schritt miteinander in Beziehung setzen und verknüpfen kann. Die entstandenen Silos lassen sich dabei intelligent verknüpfen, so dass jeder Bereich trotzdem innerhalb des Silos arbeiten kann, jedoch nach außen hin verknüpft wird. Dabei werden nicht nur rein dokumentenbasierte Ansätze unterstützt, sondern auch die direkte Verknüpfung mit neuartigen Datenquellen, die in Echtzeit Daten bereitstellen. Das so entstehende vernetzte System kann z.B. über eine graphenorientierte Datenbank oder Graphdatenbank umgesetzt werden. Im vorliegenden Beitrag wird untersucht, inwieweit die Modellierung mit gegenwärtig existierenden Lösungen für Graphdatenbanken möglich ist und welche Widrigkeiten dabei noch auftreten. Ausgehend von einem Beispiel mit einem vereinfachten Produkt- und Prozessdatenmodell der Blechmassivumformung, wird eine allgemeine Methode vorgestellt, durch die ein relationales Datenbanksystem in eine Graphdatenbank überführt werden kann. Anhand dieser Methode wird dargestellt, wie bestehende Lösungen teilweise auch parallel zu neuartigen Linked Data Datenbanken existieren können, um diese Schritt für Schritt in eine Graphdatenbank zu überführen. Anschließend wird die einfache Abfrage und Darstellung von Produktdaten aufgezeigt und Möglichkeiten beschrieben neuartige Datenquellen (z.B. Sensordaten aus dem Feld) für die Anbindung an die Graphdatenbank bereitzustellen. Darüber hinaus können die so erfassten Produkt- und Prozessdaten über semantische Schnittstellen für Prozesse auf organisational höherliegenden Ebenen bereitgestellt werden. Die Ergebnisse des Beitrags sind auf der einen Seite das allgemeine Vorgehensmodell zur Einführung von Graphdatenbanken. Auf der anderen Seite die Nutzbarkeitsanalyse der vorgestellten Lösung für das Produktdatenmanagement.<br
Keywords: Graphdatenbanken; Produkdaten; Prozessdaten; PLM; Datenmodell

Einsatz von Maschinellem Lernen zur Vorhersage von Schmierfilmparametern in abweichungsbehafteten elastohydrodynamischen Linienkontakten - Feile, Klara; Bartz, Marcel; Wartzack, Sandro (65. Tribologie-Fachtagung 2024. Reibung, Schmierung und Verschleiß. Forschung und praktische Anwendungen., 2024)

Einsatz von Process-Mining zur Erweiterung der semantischen Produktbeschreibung - Sauer, Christopher; Dworschak, Fabian; Schleich, Benjamin; Wartzack, Sandro (Design for X. Beiträge zum 29. DfX-Symposium, 2018)
Due to the increased data volume in product development, the use of PDM systems has become established. Current trends show a shift away from the monolithic integrated product model towards a semantic product model. In order to extend this product model by a description of the manufacturing process, which is particularly important against the background of the digital twin, methods of process mining are suitable. The result of these methods is always a model of the given process, which is to be fed to the higher-level system via a semantic interface. Thus, ontologies that enable a semantic description are suitable for the interface definition. Within the scope of this article, based on an exemplary manufacturing process, process mining is applied and a prototypical interface is designed.<br
Keywords: process mining; semantic product modeling; ontologies

Einsatz von Rousseau Modellen für die Vorhersage menschlicher Bewegung zur muskuloskelettalen Simulation im AnyBody Modeling System - Wolf, Alexander; Miehling, Jörg; Wartzack, Sandro (7. CADFEM medical conference, 2017)
Biomechanische Simulationsmethoden ermöglichen die Analyse und Bewertung von Bewegungen und Kräften des menschlichen Bewegungsapparates. Dadurch wird es möglich Fragestellungen bezüglich ergonomischer/ biomechanischer Parameter in frühen Planungsphasen zu beantworten und diese entsprechend in die Planung einfließen zu lassen. So lässt sich beispielsweise ein Arbeitsablauf bereits bei der Planung nach ergonomischen Gesichtspunkten ausrichten, oder ein Produkt schon in den frühen Entwicklungs- und Konstruktionsabschnitten nach nutzerspezifischen Kriterien gestalten. Dennoch sind biomechanische Simulationsmethoden im industriellen Umfeld bei weitem nicht so verbreitet, wie herkömmliche Simulationsmethoden der Mehrkörpersimulation, oder der Strukturmechanik. Dies liegt insbesondere daran, dass für jedes neu erstellte biomechanische Modell neue Messungen stattfinden müssen, damit dieses berechnet werden kann. Für den weitläufig genutzten Ansatz der inversen Dynamik werden als Eingangsdaten die Bewegung und die externen Kräfte benötigt, welche klassischerweise in Bewegungsanalyselaboren erfasst werden müssen. Unter deren Angabe können die Muskelkräfte und die Beanspruchung der Gelenke berechnet werden. Gegenwärtig erscheint dieser Aufwand gegenüber dem Nutzen allerdings als nicht gerechtfertigt. Der Nutzen der biomechanischen Simulationsmethoden steht indes außer Frage. Deshalb gilt es den zu betreibenden Aufwand zu reduzieren. Dies kann durch Modelle geschehen, die eine Vorhersage der üblicherweise zu messenden Eingangsdaten ermöglichen. Die Vorhersage der äußeren Kräfte lässt sich im Rahmen des Optimierungsproblems der inversen Dynamik durchführen. Die Vorhersage der Bewegung kann mittels der Verwendung von Rousseau Modellen gelingen. Diese zwingen einem muskuloskelettalen Menschmodell gewisse Zwangsbedingungen auf, welche gemäß der zu erzeugenden Bewegung unterschiedlich gewichtet werden. Durch dieses Aufzwingen, von sich teilweise wiedersprechenden Zwangsbedingungen, wird das muskuloskelettale Menschmodell zu einem kinematisch überbestimmten Fall. Mithilfe eines Optimierungsverfahrens lässt sich der bestmögliche Kompromiss zur Erfüllung der Zwangsbedingungen finden, wodurch wiederum die Vorhersage einer nachvollziehbaren Bewegung möglich wird. Diese Vorgehensweise wird anhand eines konkreten Anwendungsfalles unter Zuhilfenahme des AnyBody Modeling System vorgestellt.

Ein simulationsbasierter Ansatz zur Auslegung additiv gefertigter FLM-Faserverbundstrukturen - Völkl, Harald (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2022)
Additive Fertigungsverfahren erlauben große Designfreiheiten, die durch Design for Additive Manufacturing (DfAM) ausgeschöpft werden können. An AM-Leichtbauteile werden besonders hohe Steifigkeits- und Festigkeitsanforderungen gestellt. Hierfür eignen sich besonders Faser-Kunststoff-Verbunde. Mit dem Fused Layer Modelling-(FLM-)Verfahren lässt sich die ausgeprägte Anisotropie der Faser-Kunststoff-Verbunde im Vergleich zu anderen AM-Verfahren sehr zielgerichtet einsetzen. In dieser Dissertation wird daher ein strukturierter DfAM-Ansatz zur Auslegung kurzfaserverstärkter FLM-Leichtbauteile vorgestellt. Dieser berücksichtigt die orthotropen Materialeigenschaften zunächst durch eine Baurichtungsoptimierung, die den Kraftfluss im Bauteil möglichst planar in der Druckplattformebene führt. Anschließend folgt eine Topologieoptimierung mit orthotropem Materialmodell, die sowohl Außengestalt als auch Infill simultan optimiert. Eine Extrusionspfadgenerierung überführt Ergebnisse dann in druckbare Bauteile. Eine strukturmechanische FLM-Simulation erlaubt den Vergleich verschiedener FLM-Bauteile mit verschiedenen Infill-Mustern. Zur Demonstration wird ein Tragwerksknoten unter zwei Lastfällen mit dem neuen Ansatz optimiert. Die entstehende Geometrie; dieselbe Geometrie, jedoch mit anderen Infill-Mustern; und eine konventionell ausgelegte Variante werden mittels FLM-Simulation verglichen. Die Ergebnisse zeigen einen deutlichen Steifigkeitsgewinn des neuen Ansatzes gegenüber konventionellen Alternativen, der Produktentwickelnde zudem strukturiert durch den DfAM-Prozess mit seinen herausfordernden Designfreiheiten führt.
Keywords: Additive Fertigung; Faserverbund; Leichtbau; Simulation; Design for Additive Manufacturing; Fused Layer Modelling; Fused Deposition Modeling; Rapid Prototyping; Ingenieurwissenschaften; Maschinenbau; Produktionstechnik

Ein Vergleich von Datenanalysemethoden für eine Affective Engineering Methode - Zöller, Susan; Schröppel, Tina; Wartzack, Sandro (Design for X. Beiträge zum 28. DfX-Symposium, 2017)
Affective Engineering (AE) is an engineering genre that deals with users’ subjective value creation in technical product design. Therein, quantitative instruments to map subjective quality criteria are dominant. ACADE is such an instrument that focuses on a long-term alignment of product design impres-sions to the subjective needs of users. Due to its quantitative backbone, sev-eral mathematical analysis methods seem convenient, whereas their specific benefits and drawbacks are not yet clear in the AE context. Therefore, anal-yses of nonlinear regression, artificial neural networks, fuzzy logic systems and hybrids are examined under the aspect of ACADE applicability. Different quality indicators unveil characteristics which the designer may use to mine their potential for future AE analyses.
Keywords: affective engineering; nonlinear regression; fuzzy logic systems; artificial neural networks

Ein von nachgiebigen Mechanismen inspirierter Ansatz zur Konzeptionierung von additiv gefertigten Soft Robots - Steck, Patrick; Völkl, Harald; Wartzack, Sandro (Konstruktion, 2023)
Die ausgeprägten Designfreiheiten durch die additive Fertigung finden besonders in der Gestaltung von Soft Robots Anwendung. UnterSoft Robotic wird ein junges und schnell wachsendes Forschungsgebiet verstanden, welches durch variable und steuerbare Nachgiebigkeiten innerhalb der Strukturen Lösungen für verschiedene Bewegungsprobleme finden möchte. Die Bauteile werden dabei häufig als Vorabmodell aus Gründen der Funktionsintegration additiv hergestellt. Durch die Funktionsintegration können z. B. bewegliche Baugruppen durch ein Einzelbauteil höherer Komplexität substituiert und somit Wirkungsgrade verbessert, Massen reduziert und Montagezeiten verkürzt werden. Dies entspricht in den Zielen den Nachgiebigen Mechanismen, welche jedoch aktuell noch nicht im Kontext von Soft-Robotics betrachtet werden und deshalb auch keine Konzeptions- oder Designvorschriften für diesen Anwendungsfall existieren. Im vorliegenden Beitrag wird ein Ansatz zur Konzeptionierung von Soft Robots vorgestellt, welche auf einer Kombination aus der Konstruktionsmethodik nach Pahl/Beitz und einer Auslegungsmethodik für nachgiebige Mechanismen basiert. Hierbei wurden verschiedene additiv gefertigte Soft Robotic Greiferkonzepte verglichen und parallel unterschiedliche Aktivierungsformen in der Soft Robotic untersucht. Die Soft Robotic Greifer können zur Manipulation von Gegenständen, beispielsweise in der Lebensmittelindustrie, verwendet werde
Keywords: Soft Robotic; Compliant Mechanism; Multi-Material; Fused-Layer-Modelling

Ein Werkzeug zur schnellen Konfiguration biomechanischer Simulationen in der Produktentwicklung - Krüger, Daniel; Wartzack, Sandro (Entwerfen Entwickeln Erleben. Methoden und Werkzeuge in der Produktentwicklung (10. Gemeinsames Kolloquium Konstruktionstechnik 2012), 2012)
UnivIS-Import:2015-04-16:Pub.2012.tech.FT.FT-KLMEFK.einwer

Elastohydrodynamische Simulation tribologischer Kontakte in Wälzlagern - Wirsching, Sven; Winkler, Andreas; Bartz, Marcel; Wartzack, Sandro (Konstruktion, 2023)
Using the thermo elastohydrodynamic simulation tool „TriboFEM“ developed at the KTmfk, the friction of secondary roller face/ring side contacts is calculated taking into account exact geometries as well as the wear-induced profile change of primary raceway contacts. The results of the simulations are discussed and the potential for use in the design of rolling bearings is shown. TriboFEM can thus support the development of energy-efficient technical drive systems, which is becoming increasingly important against the background of resource scarcity and climate protection.<br

Electrified cross skate as a micromobility solution | Elektrifizierter Cross-Skate als Mikromobilitätslösung - Kramer, Vincent; Wirsching, Sven; Wartzack, Sandro; Miehling, Jörg (Konstruktion, 2023)
Climate change, resource scarcity and progressing urbanization give rise to challenges in the development of contemporary mobility solutions. In this context, electrically powered vehicles are becoming increasingly important. Innovative micromobility solutions can contribute to resource-, environment- and infrastructure-friendly passenger transport, especially in urban areas. This paper presents such a solution in the form of an electrified cross skate with a steerable front axle. The electric drive can compensate for the relatively high rolling resistance of conventional cross-skates, while the steering enables easier cornering. As another special feature, the skate has a hybrid driving mode in which the rider moves by muscle power in the skating technique with support of an electric motor.
Created from Fastlane, Scopus look-up

Elementary affordances: A study on physical user-product interactions - Wolf, Alexander; Miehling, Jörg; Wartzack, Sandro (Procedia CIRP 91, 2020)
Digital human models enable a pro-active and virtual assessment of ergonomics in design. Despite this huge potential, possibilities of user-product interaction modelling, in terms of postures or movement generation, are limited and poorly integrated in common virtual design tools. To address this deficiency, we propose the concept of “elementary affordances”. These universally describe parts of human interaction behavior and shall serve as a modelling interface for posture and movement prediction algorithms. This paper presents an empirical study, identifying 18 elementary affordances, proving that parts of human interaction behavior can be described via a relatively small set of elementary affordances.<br
Keywords: design for ergonomics; human centered design; user centred design; user-product interaction; digital human models; affordances; human factors; computer aided engineering; virtual engineering; computer aided design

Emotional Bionics - A Pickup truck is a Lion! A Study Using Emotional Profiling to Analyse Bionic Analogies in Car Design - Zöller, Susan; Schröppel, Tina; Wartzack, Sandro (7th International Conference on Kansei Engineering & Emotion Research 2018, 19-22 March 2018, Kuching, Malaysia, 2018)
So far, bionic design has mainly been systematically applied to support functional solutions. But in recent times, subjective aspects in product quality became increasingly important to users too. Under the aspect of a sustainable, targeted value creation for users, bionic design may also help to better address users' subjective needs in product design. Therefore, a new method 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.
Keywords: Emotional Bionics; Subjective Value Creation; Kansei Engineering; Design Analytics

Enabling Initial Design-Checks of Parametric Designs Using Digital Engineering Methods - Gerschütz, Benjamin; Bickel, Sebastian; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the Design Society, 2022)
The world consequently gets faster, so does product development. Therefore, the stock of development and simulation data increases continuously. Unfortunately, inexperienced users cannot cope with the rising number of simulation requests in the time needed. Digital Engineering opens potentials to support the users with newly developed methods and tools. In this contribution, we present a method to assist designers, inexperienced in finite-element simulations to perform an initial check of changed parametric designs independently, quickly and with support in interpreting the results.<br
Keywords: digital design; data-driven design; supportive technologies; finite element method (FEM)

Energieeffizienz durch Tribometrie: Untersuchung von Reibungsmessgrößen am Beispiel des Kontakts beschichteter Tassenstößel/Nocken - Dobrenizki, Ladislaus; Musayev, Yashar; Tremmel, Stephan; Hosenfeldt, Tim; Wartzack, Sandro (Reibung, Schmierung und Verschleiß - Forschung und praktische Anwendungen, 2015)
Aufgrund der Systemabhängigkeit tribologischer Kenngrößen wird die Übertragbarkeit von Reibungsmessgrößen zwischen unterschiedlichen tribologischen Systemen erschwert. Am Beispiel des komplexen tribologischen Kontakts Tassenstößel/Nocken wurde der Einfluss der in diesem Tribosystem vorliegenden Pressungen auf die Reibung im Kugel-Scheibe-Tribometerversuch untersucht. Bei beiden tribologischen Prüfständen wurden gleiche Materialpaarungen und das gleiche Motorenöl verwendet. Für die Versuche wurden DLC beschichtete und nicht beschichtete mechanische Tassenstößel aus dem Werkstoff 16MnCr5 herangezogen. Die Betrachtung der Pressung im Kugel/Scheibe-Kontakt erfolgte über die Auswahl initialer Pressungen auf Basis einer Beanspruchungsanalyse des betrachteten Tassenstößel/Nocken-Kontakts. Weiterhin wurde noch die Gleitgeschwindigkeit variiert. Die aus dem Tribometerversuch gewonnen Zusammenhänge wurden mit Ergebnissen aus Versuchsläufen an einem Tassenstößel-Reibungsprüfstand verglichen. Es konnte ein unterschiedliches Reibungs- und Verschleißverhalten der Kontaktpartner in Abhängigkeit von der Initialpressung am Kugel-Scheibe Tribometer festgestellt werden. Zudem konnten bei den unbeschichteten und DLC beschichteten Tassenstößel unterschiedlich wirkende Tribomechanismen bei verschiedenen Lastkollektiven nachgewiesen werden. Im Falle gleicher Öltemperaturen wurden ähnliche Zusammenhänge im Tassen/Nocken-Kontakt wie im Kugel-Scheibe-Kontakt beobachtet.
Keywords: Energieeffizienz im Ventiltrieb; Mechanischer Tassenstößel; Diamantähnlicher amorpher Kohlenstoff; Tribometrie

Energieeffizienz und Ressourcenschonung durch beschichtete Wälzlager - Sander, Thomas; Kröner, Julia; Dobrenizki, Ladislaus; Tremmel, Stephan; Wartzack, Sandro; Hosenfeldt, Tim; Musayev, Yashar (Konstruktion, 2014)
UnivIS-Import:2015-03-09:Pub.2014.tech.FT.FT-KLMEFK.energi

Enhancement of Surgical Planning through Patient-Specific Biomechanical Modeling and Simulation - Sesselmann, Stefan; Miehling, Jörg; Wartzack, Sandro; Forst, Raimund (37th SICOT Orthopaedic World Congress, 2016)
Current surgical planning software for total endoprostheses of hip and knee joints focuses mainly on geometric arrangements in 2D or in some cases even in 3D. Since this standard process relies highly on the experience of the orthopedic surgeon, poorly adjusted planning parameters may impede the expected mobility outcome. Therefore, we propose the inclusion of a methodology for the individualization of generic musculoskeletal models based on a limited number of input parameters into the planning process. These parameters can ideally directly be taken from the standard tests in advance of the joint replacement to allow for a highly usable planning tool. For example the bones and rotational axes are adjusted using landmark distances measured in the compulsory X-ray images, joint mobility can be localized using the neutral zero method and muscular dysfunctions can be semiquantified by measuring the degree of force according to the BMRC. Also irregularities or deformities can be considered. The resulting model is eventually used for patient-specific simulations to derive useful information on how the total endoprosthesis has to be geometrically set up to yield the best biomechanical result. Sensitivity analysis is to be performed as the orthopedist can hardly reproduce the specified values exactly. He rather needs intervals in which the postoperative outcome is robust to variations in the geometric parameters to be able to choose the best parameter configuration. This analysis can also predict which parameters have to be precisely met and which play a subordinate role.

Enhancing Dynamic Consistency of Multimodal Motion Data in Musculoskeletal Simulation - Wechsler, Iris; Wolf, Alexander; Wartzack, Sandro; Miehling, Jörg (27th Congress of the European Society of Biomechanics, 2022)
Introduction Digital human models can be used to determine biomechanical parameters (e.g. muscle or joint reaction forces) virtually and in a non-invasive way [1]. Hereby, subject-specific models lead to more reliable simulation results in this context [2]. Moreover, even though current sensor and measuring systems can achieve high-quality data, the measurements are still error-prone and subject to uncertainties such as noise or jumps. Furthermore, kinematic and dynamic inconsistencies between the measured data and the motion capabilities of the human body can occur. We assume that motion tracking accuracy and consistency will be increased when multimodal data, e.g., some combination of position, orientation, EMG, or surface data, is considered. Therefore, our goal is to research and develop methods for filtering and analysing multimodal motion measurement data in conjunction with individualized digital human models. In this paper we want to discuss available approaches. Methods Subject-specific individualization of the applied musculoskeletal human models in multiple domains (anthropometry, mobility, strength) is to be achieved through a combination of subject-specific manual measurements and population data [3]. Further, we aim to develop a method for kinematically consistent and precise motion tracking. The standard method, Inverse Kinematics, minimises the difference between measured and virtual marker and coordinate positions in a least squares approach to compute generalized coordinate trajectories [4]. The novel tracking algorithm should include different types of data, which are weighted in relation to each other. This way the observed movement information from different data sources should be transferred to the digital model in order to get the most accurate and consistent simulation results possible. Nevertheless, the problem regarding the dynamic consistencies between the motion of the model and the measurements still remains. For this we also want to investigate methods to enhance dynamic consistency and further develop a dynamic tracking method that is able to generate kinematically and also dynamically consistent motion data. Therefore, dynamic components (e.g. muscle activation, accelerations) are to be included in the tracking method. Results There are various approaches available in literature for enhancing dynamic consistency (cf. figure 1). The EMG-informed forward simulation approach, for example, tracks measured marker trajectories while replicating EMG measurements to obtain dynamic consistency [5-7]. Controller-based solution approaches optimise measured trajectories through forward simulation with a time-limited observation interval to enhance dynamic consistency [8]. Also, trajectory optimization using direct collocation and a Kalman filter have already been used to achieve dynamically consistent movement simulations [9,10]. Discussion In the next step, a systematic literature review will be conducted based on the mentioned results, in order to identify and analyse all relevant dynamic tracking solutions regarding multimodal motion data. Main focus will be the classification into different solution approaches. Moreover, input and output variables, the used model and the regarded dynamic component will be explored. Based on these results the solution approach for our application of multimodal motion data is to be set up. This new musculoskeletal simulation approach is then to be evaluated regarding accuracy and usability and to be benchmarked against the standard methods of biomechanical motion capture and analysis. References 1. Seth et al, Computational Biol, 14(7), 2018. 2. Lund et al, Internat Biomech, 2:1-11, 2015. 3. Miehling, Comput Methods Biomech Biomed Engin, 22(15):1209-1218, 2019. 4. Delp et al, IEEE Trans Biomed Eng, 54: 1940-1950, 2007. 5. Sartori et al, PLoS One, 7(12), 2012. 6. Bailly et al, Front Bioeng Biotechnol, 2021. 7. Moissenet et, Front. Neurorobot, 2019. 8. Thelen et al, J Biomech, 39:1107-1115, 2006. 9. Dembia et al, PLoS Comput Biol, 16(12), 2020. 10. Bonnet et al, J Biomech, 62:140-147, 2017. Acknowledgements This work was (partly) supported by the Deutsche Forschungs-gemeinschaft (DFG, German Research Foundation) under Grant SFB 1483–Project-ID 442419336. <br

Enhancing Mechanical and Biomedical Properties of Protheses - Surface and Material Design - Shah, Raj; Gashi, Blerim; Hoque, Sharika; Marian, Max; Rosenkranz, Andreas (Surfaces and Interfaces, 2021)
The long-term success of prosthetics greatly relies on the biomechanical/medical properties of the implanted material. Inadequate biocompatibility or poor wear resistance can lead to devastating repercussions including osteolysis, tissue inflammation, and implant failure, which require revisionary surgery, thus being costly and painful for the patient. Therefore, special attention has been given to the modification/treatment of prosthetic surfaces to enhance cell proliferation and bio-tribological performance as well as to improve tendon-growth and mobility. The advanced usage of porous structures and surface textures represents an innovative approach towards promoting the growth of healthy soft tissue rather than cicatricial tissue as well as enhancing wear and the lubricative performance. Other prosthetic surface modifications including plasma immersion ion implantation (PIII), the application of bio-tribologically effective coatings or the introduction of carbon nanotubes (CNTs) as reinforcement have also emerged. The identification of the optimal prosthetic materials (UHMWPE, HXLPE, Ti6Al4V, or CoCrMo) as well as the application of relevant surface modifications or treatments serves as a vital opportunity in enhancing the protheses’ longevity and performance. Therefore, this article seeks to compile recent and fundamental research trends surrounding these methods with a special emphasis towards improving the tribological properties, cell proliferation, and overall prosthetic success of biomaterial
Keywords: Biotribology; prothesis’ longevity; porosity; surface texturing; DLC coatings; plasma immersion ion implantation

Enhancing the Design of Experiments on the Fatigue Life Characterisation of Fibre-Reinforced Plastics by Incorporating Artificial Neural Networks - Witzgall, Christian; Ashhab, Moh’d Sami; Wartzack, Sandro (Materials, 2024)
Fatigue life testing is a complex and costly matter, especially in the case of fibre-reinforced thermoplastics, where other parameters in addition to force alone must be taken into account. The number of tests required therefore increases significantly, especially if the influence of different fibre orientations is to be taken into account. It is therefore important to gain the greatest possible amount of knowledge from the limited number of available tests. In order to achieve this, this study aims to utilise adaptive sampling, which is used in numerous areas of computational engineering, for the design of experiments on fatigue life testing. Artificial neural networks (ANNs) are therefore trained on data for the short-fibre-reinforced material PBT GF30, and their areas of greatest model uncertainty are queried. This was undertaken with ANNs from various numbers of hidden layers, which were analysed for their performance. The ideal case turned out to be four hidden layers, for which a squared error as small as 1 × 10−3 was recorded. Locally resolved, the ANN was used to identify the region of greatest uncertainty for samples of vertical orientation and small numbers of cycles. With information such as this, additional data can be obtained in such uncertain regions in order to improve the model prediction—almost halving the recorded error to only 0.55 × 10−3. In this way, a model of comparable value can be found with less experimental effort, or a model of better quality can be set up with the same experimental effort.
CRIS-Team Scopus Importer:2024-02-23
Keywords: artificial neural networks; composites; design of experiments; fatigue life; increased efficiency; short-fibre-reinforced thermoplastics

Enhancing the flow of information in the PLM by using numerical DSMs – an industrial case study - Luft, Thomas; Bochmann, Johanna; Wartzack, Sandro (Proceedings of the IFIP WG5.1, 2013)
This paper proposes a methodology to enhance the information flow in the product life cycle through the example of the product development process. The methodology refines the existing approaches of revealing indirect dependencies with a multiple domain matrix by introducing the numerical derived design structure matrix as indicator of quantifying indirect dependencies between process steps, information and people. These dependencies are quantified by the pieces of information causing the indirect linkage. The subsequent analysis is narrowed down to the content level of information to identify the root causes. This methodology has been successfully tested in an industrial case study. As a result, this paper helps to manage the complexity in the PLM by making the linkages caused by the information flow visible to improve collaborative product development.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.enhanc
Keywords: Collaborative product development; information management; process management; design structure matrix; multiple domain matrix; case study

Entwicklung beanspruchungsgerechter CFK-Laminate in den frühen Phasen der Produktentwicklung - Klein, Daniel; Caballero, Steffen; Wartzack, Sandro (ANSYS Conference & 32. CADFEM Users' Meeting, 2014)
Keywords: Leichtbau; Composites; Simulation

Entwicklung eines bioinspirierten Gelenkarmroboters mithilfe der Kopplung von Mehrkörpersimulation und Topologieoptimierung - Bartz, Marcel; Gößling, Rainer; Remus, Robin; Schafran, Tommy; Bender, Beate (Conference Proceedings: 35. CADFEM ANSYS Simulation Conference, 2017)

Entwicklung eines mehrphasigen FE-Modells zur Analyse der mechanischen Spannungen im Oberschenkelknochen unter physiologischen Belastungen - Bartz, Marcel; Waschinsky, Navina; Gößling, Rainer; Bender, Beate; Ricken, Tim (Conference Proceedings: 34. CADFEM ANSYS Simulation Conference, 2016)

Entwicklung eines Vorgehens zur automatisierten Auslegung zyklisch belasteter, endlosfaserverstärkter Bauteile - Gadinger, Marc; Bode, Christoph; Wartzack, Sandro (Proceedings from the NAFEMS DACH Conference 2024, 2024)
Bauteile aus Faserverbundwerkstoffen werden zunehmend als wichtige Strukturbauteile im Serieneinsatz verwendet. Dort sind sie häufig zyklischen Belastungen ausgesetzt, die mit steigender Zyklenzahl durch Mikrorissbildung und -ausbreitung zu einer Verschlechterung bzw. Degradation der Werkstoffeigenschaften führen. Bisherige Auslegungsansätze und Optimierungsroutinen berücksichtigen die Betriebsfestigkeit jedoch kaum. Vielmehr erfolgt meist eine Überdimensionierung nach empirischen Kriterien. Um das volle Leichtbaupotenzial eines Bauteils auszuschöpfen, ist jedoch eine gezielte Auslegung auf eine definierte Lebensdauer zielführend. Um diese Lücke zur gezielten Betriebsfestigkeitsauslegung von Faserverbundbauteilen zu schließen, wird am KTmfk eine neue Auslegungsmethode zur Berücksichtigung des Ermüdungsverhaltens von Faser-Kunststoff-Verbunden entwickelt. Ziel ist dabei die lokale Verstärkung eines Basislaminats, um sicherzustellen, dass der Faser-Kunststoff-Verbund eine geforderte, minimale Schwingspielzahl erreicht. Dazu werden die im Bauteil wirkenden Spannungen und Dehnungen mittels einer Finiten-Elemente-Analyse ermittelt und örtlich aufgelöst pro Schicht und Element betrachtet. Mit Hilfe eines mathematischen Versagensmodells wird so für jedes Element die maximale bis zum Versagen ertragbare Schwingspielzahl berechnet. Die dafür notwendigen Kenntnisse über das anisotrope Festigkeitsverhalten liefern zyklische Versuche an unidirektionalen Probekörpern. Der erste Schritt zur Verbesserung des Langzeitverhaltens besteht darin, Patches an den in der Simulation identifizierten kritischen Bereichen anzubringen. Parallel dazu werden die Faserorientierungen der Lagen optimiert, indem sie an die Hauptrichtungen der größten Spannungen angepasst werden. Weitere Simulationen werden durchgeführt, um die Positionen und die Anzahl der Patch-Lagen, die Dicke der einzelnen Lagen und die Schichtreihenfolge zu optimieren. Das abschließende Post-Processing stellt sicher, dass am Ende der Optimierung ein fertigungsgerechtes Design vorliegt. Dazu werden ähnliche Patches mittels Clustering zusammengefasst. Die Neuheit und Einzigartigkeit dieses Ansatzes liegt in der Kombination der Laminatoptimierung dynamisch beanspruchter Strukturen mit der Flexibilität des Fiber Patch Placement. Damit ermöglicht die Methode eine flexible und gezielte Verbesserung des Betriebsfestigkeitsverhaltens unter Berücksichtigung des Leichtbaugedankens.<br
Keywords: Leichtbau; Betriebsfestigkeit; Laminatoptimierung; Faser-Kunststoff-Verbund

Entwicklung eines Vorgehens zur Toleranzoptimierung an Faser-Kunststoff-Verbund Bauteilen - Franz, Michael; Schleich, Benjamin; Wartzack, Sandro (Summer School Toleranzmanagement - Beiträge zur 4. Summer School - September 2020, 2020)

Erarbeitung von Gestaltungsrichtlinien für die Konstruktion additiv gefertigter Mechanismen - Hallmann, Martin; Schleich, Benjamin; Wartzack, Sandro (Konstruktion für die Additive Fertigung 2018, 2020)
Additive Fertigungsverfahren haben sich aufgrund ihrer losgrößenunabhängigen Fertigungskosten und der großen Gestaltungsfreiheit sowohl in der Forschung als auch in der industriellen Anwendung erfolgreich etabliert. So werden die verschiedenen additiven Verfahren nicht mehr nur für die Herstellung von Prototypen, sondern vermehrt zur Fertigung komplexer, endkonturnaher Bauteile und gesamter Baugruppen angewendet. Dabei konnten in den letzten Jahren zahlreiche Richtlinien für die Gestaltung der schichtweise aufgebauten Bauteile hergeleitet werden. Eine umfassende Betrachtung additiv gefertigter Gelenke fehlt jedoch bisher. Um den Produktentwickler bzw. Konstrukteur bei der Gestaltung von mittels Fused Deposition Modeling (FDM) hergestellten Drehgelenken zu unterstützen, werden im nachfolgenden Beitrag relevante Aspekte, wie z. B erforderliche Mindestspalte zur Trennung von nicht- und einfach-gekrümmten Elementen, aufgezeigt. Versuchsergebnisse dienen dabei als Basis für die Ableitung von Richtlinien für das Design FDM-gedruckter Gelenke und ergänzen dadurch die Grundsätze des Design for Additive Manufacturing. Die Umsetzung der erarbeiteten Gestaltungsrichtlinien wird anschließend exemplarisch an einem ebenen Mechanismus dargelegt.<br
Keywords: Design for Additive Manufacturing; Montagefreie; additiv gefertigte Mechanismen; Gestaltungsrichtlinien; Fused Deposition Modeling; Gelenke

Ermittlung eines Skelettierungsverfahrens zur Konvertierung von Topologieoptimierungsergebnissen - Mayer, Johannes; Wartzack, Sandro (Proceedings of the 31st Symposium Design for X (DFX2020), 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.<br
Keywords: Computational Geometry; Topology Optimization; Medial Axis Transform; Surface Skeleton

Erweiterte Systemmodellierung - Integration impliziter Wissenselemente in die Erstellung technischer Systemmodelle - Wilking, Fabian; Walter, Leonie; Schleich, Benjamin; Wartzack, Sandro (Beiträge zum 31. DfX Symposium, 2020)
The increasing complexity of technical consumer products has led to the integration of Model-Based Systems Engineering (MBSE) approaches into sectors that are not viewed as classic users of Systems Engineering. The approach helps grasping the complexity and keeping costs at a low level. However, many companies struggle with the implementation of the approach into their processes. A regularly mentioned reason for this is a missing visibility of a clear benefit. Especially smaller enterprises are facing these problems within the value chain. This paper presents an approach to contribute towards the enhancement of MBSE accessibility. It shows different strategies for the integration of tacit knowledge into system models and discusses their feasibility and contribution towards this enhancement.
Keywords: Systems Engineering; Model-Based Systems Engineering; System Model; Knowledge Management; Tacit Knowledge

Erweiterung der Wälzlagerdynamiksimulation um die Schmierstoffhydrodynamik des Kontakts Käfig/Außenring - Seiler, Katrin; Stadler, Marion; Tremmel, Stephan; Hahn, Bodo; Graf-Goller, Oliver; Wartzack, Sandro (3. Wissenschaftliches Wälzlagerkolloquium, 2014)
Keywords: Wälzlager; MKS; Tribologie; Hydrodynamik

Estimation of Clinch Joint Characteristics Based on Limited Input Data Using Pre-Trained Metamodels - Zirngibl, Christoph; Schleich, Benjamin; Wartzack, Sandro (AI, 2022)
Given strict emission targets and legal requirements, especially in the automotive industry, environmentally friendly and simultaneously versatile applicable production technologies are gaining importance. In this regard, the use of mechanical joining processes, such as clinching, enable assembly sheet metals to achieve strength properties similar to those of established thermal joining technologies. However, to guarantee a high reliability of the generated joint connection, the selection of a best-fitting joining technology as well as the meaningful description of individual joint properties is essential. In the context of clinching, few contributions have to date investigated the metamodel-based estimation and optimization of joint characteristics, such as neck or interlock thickness, by applying machine learning and genetic algorithms. Therefore, several regression models have been trained on varying databases and amounts of input parameters. However, if product engineers can only provide limited data for a new joining task, such as incomplete information on applied joining tool dimensions, previously trained metamodels often reach their limits. This often results in a significant loss of prediction quality and leads to increasing uncertainties and inaccuracies within the metamodel-based design of a clinch joint connection. Motivated by this, the presented contribution investigates different machine learning algorithms regarding their ability to achieve a satisfying estimation accuracy on limited input data applying a statistically based feature selection method. Through this, it is possible to identify which regression models are suitable to predict clinch joint characteristics considering only a minimum set of required input features. Thus, in addition to the opportunity to decrease the training effort as well as the model complexity, the subsequent formulation of design equations can pave the way to a more versatile application and reuse of pretrained metamodels on varying tool configurations for a given clinch joining task.<br

Estimation of Composite Laminate Ply Angles Using an Inverse Bayesian Approach Based on Surrogate Models - Franz, Michael; Pfingstl, S.; Zimmermann, M.; Wartzack, Sandro (2022)
A digital twin (DT) relies on a detailed, virtual representation of a physical product. Since uncertainties and deviations can lead to significant changes in the functionality and quality of products, they should be considered in the DT. However, valuable product properties are often hidden and thus difficult to integrate into a DT. In this work, a Bayesian inverse approach based on surrogate models is applied to infer hidden composite laminate ply angles from strain measurements. The approach is able to find the true values even for ill-posed problems and shows good results up to 6 plies.<br
Keywords: digital twin; inverse problem; simulation-based design; data-driven design; structural analysis

Evaluation of Active Shoulder Exoskeleton Support to Deduce Application-Oriented Optimization Potentials for Overhead Work - Sänger, Johannes; Yao, Zhejun; Schubert, Tim; Wolf, Alexander; Molz, Carla; Miehling, Jörg; Wartzack, Sandro; Gwosch, Thomas; Matthiesen, Sven; Weidner, Robert (Applied Sciences, 2022)
Repetitive overhead work with a heavy load increases the risk for work-related shoulder disorders. Occupational exoskeletons supporting arm elevation are potential solutions to reduce that risk by lowering the physical strains on the shoulder. Many studies have reported a reduction in shoulder stress in various overhead tasks by using such exoskeletons. However, the support demand can vary in each phase of motion as well as in each individual task. This paper presents a laboratory study with five participants to evaluate the influence of the support level of an active shoulder exoskeleton in different motion phases (e.g., arm lifting, screw-in, and arm lowering of two overhead tasks) to identify the potential optimization of support at each phase. Results show that the support level of the exoskeleton should be adapted to the motion phase of the two chosen tasks. A higher support force is desired for the screw phase compared to the arm lifting and lowering phases, and the support level needs to be reduced immediately for arm lowering after the screw phase. The time for switching the support levels can be recognized by the electric current of the screwdrive
Keywords: human–machine interaction; biomechanical analysis; sEMG; interaction forces; user experience; power tool; exoskeleton

Evaluation of DLC, MoS2, and Ti3C2Tx thin films for triboelectric nanogenerators - Tremmel, Stephan; Luo, Xiongxin; Rothammer, Benedict; Seynstahl, Armin; Wang, Bo; Rosenkranz, Andreas; Marian, Max; Zhu, Laipan (Nano Energy, 2022)
Due to their cost-effective fabrication, easy integration, and low frequency working range, triboelectric nanogenerators (TENGs) demonstrate tremendous potential in green energy harvesting to power smart devices and the internet of things (IoT). However, there is an urgent need to synergistically maximize their output and improve their durability to ensure a long-lasting high performance. This study aims at elucidating the performance of protective thin films deposited on the wear-prone PTFE surface of TENGs including doped and undoped, single- and multi-layer hydrogenated DLC films, MoS2 coatings fabricated by physical vapor deposition and multi-layer Ti3C2Tx (MXene) films. The deposited coatings are characterized by electron microscopy, and Raman spectroscopy. Their triboelectric performance is analyzed for TENGs operating in contact separation and freestanding sliding modes. We verified that MXenes outperformed the other films in contact separation mode due to the good electron gain ability of functional oxygen and fluorine groups. In sliding mode, the undoped a-C:H coating performed on a comparable level to the uncoated reference and superior to the tungsten-doped DLC and MoS2 films. The film withstood long-term tests without notable signs of wear; merely the output slowly decreased with time due to graphitization and thus potential material transfer to the mating body.<br
Keywords: Triboelectric nanogenerators; Energy harvesting; Amorphous carbon; 2D materials; Molybdenum disulfide; MXenes

Evaluation of geometric tolerances and generation of variational part representatives for tolerance analysis - Schleich, Benjamin; Wartzack, Sandro (International Journal of Advanced Manufacturing Technology, 2015)
Managing geometric part deviations to control their effects on the product function and quality is an important task in the design of physical artefacts. Consequently, computer-aided tolerancing tools are widely applied in industrial practice to evaluate the effects of geometric part deviations on assembly and functional requirements. However, most established models and approaches for the representation of geometric part deviations, geometric tolerances, and geometric requirements in such tools lack of a realistic consideration of form deviations and are often not conform to international standards for the geometric product specification and verification. With the aim to provide a further step towards a computer-aided tolerancing theory employing variational part representatives in discrete geometry, approaches for the generation of such representatives, which conform to pre-defined tolerance specifications, are presented. These approaches ground on algorithms for the evaluation of geometric tolerances from point clouds and are essential for the tolerance analysis employing point based models. We highlight the usefulness of the presented methods for the tolerance analysis in a typical case study.
Keywords: Tolerance design; Computer-aided tolerancing; Geometric tolerances; Variational model; Inspection

Evaluation of the effects of geometrical deviations on the fatigue life and vibrations of cylindrical roller bearings - Dahiwal, Rahul; Aschenbrenner, Alexander; Schleich, Benjamin; Wiesker, Sebastian; Kiekbusch, Timo; Tremmel, Stephan; Wartzack, Sandro; Sauer, Bernd (Bearing World Journal, 2018)
Due to uncertainties in manufacturing processes all components suffer from geometric deviations and imperfections, even high-precision components like roller bearings. In general, tolerances define the allowable deviations of components and ensure their manufacturability, mountability and operational behavior. Nevertheless, geometric deviations can still unpredictably influence the operational behavior of components. Indeed, studies have shown that deviations together with the operating clearance can significantly affect the dynamic behavior and thus the fatigue life of roller bearings. In this contribution, two simulation methods are employed in order to consider and study the effect of geometric deviations like roundness or dimensional deviations of bearings and their adjacent components (shaft and housing) on a cylindrical roller bearing’s vibrational behavior and fatigue life. First, a statistical simulation model is introduced allowing an easy way to screen the operational clearance and fatigue life of a large number of cylindrical roller bearings. Afterward, a multibody dynamic model is used to gather detailed information about the load distribution on each rolling element and the inner ring displacement during operation. These methods allow a user of roller bearings a better understanding of the correlation between geometric deviations and a roller bearing’s vibrational behavior as well as fatigue life. The methods should also aid a user to optimize the geometric definition and tolerancing of their components. After a detailed description of the methods, their application is demonstrated for a use case.
Keywords: Cylindrical Roller Bearing; Geometric Definition and Tolerancing; Statistical Variation Simulation; Dynamic simulation method

Evaluation of the surface fatigue behavior of amorphous carbon coatings through cyclic nanoindentation - Weikert, Tim; Wartzack, Sandro; Baloglu, Maximilian Volkan; Willner, Kai; Gabel, Stefan; Merle, Benoit; Pineda, Fabiola; Walczak, Magdalena; Marian, Max; Rosenkranz, Andreas; Tremmel, Stephan (Surface & Coatings Technology, 2021)
Diamond-like carbon (DLC) coatings, frequently used to reduce wear and friction in machine components as well as on forming tools, are often subjected to cyclic loading. Doping of DLC coatings with metals or metal carbides as well as the usage of multilayer architectures represent promising approaches to enhance toughness, which is beneficial for the coatings’ behavior under cyclic loading. In this study, we utilized cyclic nanoindentation to characterize the tribologically induced surface fatigue behavior of single-layer tungsten-doped (a-C:H:W) and multilayer silicon oxide containing (a-C:H:Si:O/a-C:H)25 amorphous carbon coatings under cyclic loading. Columnar growth was observed for both coatings by focused ion beam microscopy and scanning electron microscopy, while the multilayer architecture of the (a-C:H:Si:O/a-C:H)25 coating was verified by the silicon content using glow-discharge optical emission spectroscopy. In cyclic nanoindentation of the (a-C:H:Si:O/a-C:H)25 multilayer coating, stepwise small changes in indentation depth were observed over several indentation cycles. The surface fatigue process of the single-layer a-C:H:W covered a smaller number of indentation cycles and was characterized by an early steep increase of the static displacement signal. Microscopical analyses hint at grain deformation, sliding at columnar boundaries, and grain detachment as underlying fatigue mechanisms of the a-C:H:W coating, while the (a-C:H:Si:O/a-C:H)25 multilayer coating showed transgranular crack propagation and gradual fracturing. In case of the (a-C:H:Si:O/a-C:H)25 multilayer coating, superior indentation hardness (HIT) and indentation modulus (EIT) as well as a higher HIT3/EIT2 ratio suggest a higher resistance to plastic deformation. A high HIT3/EIT2 ratio, being an indicator for hindered crack initiation, combined with the capability of stress relaxation in soft layers contributed to the favorable surface fatigue behavior of the (a-C:H:Si:O/a-C:H)25 multilayer coating observed in this cyclic nanoindentation studies.
Keywords: Diamond-like carbon; Cyclic nanoindentation; Surface fatigue; Multilayer architecture

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 (24th International Conference on Wear of Materials, 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 future.<br
Keywords: Bio-tribology; Joint-prostheses; Carbon-based coatings; PVD coatings; Wear testing