3D Body Twin: Improving Human Gait Visualizations Using Personalized Avatars - Zieger, Daniel; Güthlein, Florian; Henningson, Jann-Ole; Jakob, Verena; Gaßner, Heiko; Shanbhag, Julian; Fleischmann, Sophie; Miehling, Jörg; Wartzack, Sandro; Eskofier, Björn; Winkler, Jürgen; Egger, Bernhard; et al. (ShapeMI 2024, 2024)
We propose an interactive visualization and reconstruction system for gait pattern analysis that creates a more realistic visualization of the patient than contemporary stick figure-like representations. It supports thorough gait pattern analysis, and enables unbiased inter- and intra-patient comparisons as well as longitudinal studies. Our system takes as input 3D motion capture data, but can be further constrained using readily available metadata or layman-accessible measurements. A statistical shape model is then fitted to the motion capture and personal metadata. The result is an immediate and interactive visualization of an animated 3D twin. Our system handles different marker setups and can thus be applied to already existing data. We further show that we can infer realistic body models with only a few of markers. A survey with medical experts confirms the clinical applicability of our method. <br

3. Summer School "Toleranzmanagement" und 28. Symposium "Design for X" - Wartzack, Sandro; Schleich, Benjamin (WiGeP News, 2018)
Erfolgreiche Veranstaltungen im Doppelpack: bereits zum dritten Mal trafen sich an der FAU Erlangen- Nürnberg zahlreiche Vertreter aus Lehre, Forschung und Industrie zur Summer School "Toleranzmanagement" sowie über 50 Teilnehmer aus Industrie und Forschung zum 28. Symposium "Design for X"<br

Abschlussbericht OptNeTol: Durchgängige, OPTimierungsbasierte NEnnmaß- und TOLeranzvergabe - Roth, Martin; Götz, Stefan; Wartzack, Sandro (2025)

A business model canvas for idecide - how to design a new decision making app - Luft, Thomas; Lamé, Guillaume; Ponn, Josef; Le Cardinal, Julie; Wartzack, Sandro (DS 84: Proceedings of the DESIGN 2016 14th International Design Conference, 2016)
As products become increasingly complex, product developers have to make decisions effectively and efficiently. Therefore, the long term goal of the SIG DM is to develop an iDecide App. This app should support developers in complex decision making situations during the development process. The aim of this paper is to describe possible business models for an iDecide App with the Business Model Canvas. Some business models and one industrial case study for an iDecide App are described. This should initiate an in-depth discussion on a detailed business model for an iDecide App.
Keywords: decision making; computer-aided decision making process; business model canvas; app; innovation process

A Case Study on Established and New Approaches for Optimized Laminate Design - Völkl, Harald; Franz, Michael; Wartzack, Sandro (ECCM18 - 18th European Conference on Composite Materials, 2018)
Optimized laminate design, although crucial for high-quality lightweight parts, still remains a challenge for engineers. The high number of mutually dependent parameters requires expert skills – and really good designs can only be obtained when load paths are considered appropriately, which is frequently missed out on when simply replacing isotropic material by quasi-isotropic laminate. Therefore, both commercial software solutions and approaches from research have been put forward to support engineers at finding adequate layups. In this paper, using a bike rocker arm demonstrator, a lightweight benchmark under displacement constraint is conducted with the goal of reducing mass using three approaches: OptiStruct (Altair), mfkCODE (from research) and a combination of a specific topology optimization algorithm for transversely isotropic materials and mfkCODE. The resulting conceptual designs are discussed both quantitatively and qualitatively.
Keywords: Laminate Design; Carbon Fiber Reinforced Plastics; Topology Optimization; Lightweight Design; Benchmark

Accelerating sampling-based tolerance–cost optimization by adaptive surrogate models - Roth, Martin; Freitag, Stephan; Franz, Michael; Götz, Stefan; Wartzack, Sandro (Engineering Optimization, 2024)
High numbers of function evaluations are inevitable to guarantee the reliability and optimality of sampling-based tolerance–cost optimization. Despite using different countermeasures to increase its efficiency, unreasonably long computation times and unreliable results currently hinder its profitable application. Motivated to overcome this shortcoming, this article presents a novel strategy harmonizing metaheuristic optimization and surrogate modelling. It is based on the idea of adaptive surrogate model-based optimization substituting the tolerance analysis subroutine with a surrogate model, which is iteratively re-modelled with intermediate optimization results to improve its accuracy continuously in potential optima regions. On the one hand, a directed intensification of promising solutions and, on the other hand, an accelerated exploration of the search space is achieved. Optimization studies prove its positive effect on overall efficiency, where a case study with multiple nonlinear assembly response functions and geometrical tolerances serves as a use cas
Keywords: Tolerance–cost optimization; Tolerance allocation; Sampling-based tolerance analysis; Surrogate modelling; Metaheuristic optimization

Accuracy of conventional FE-Models in Bulk-Forming of Micropins from Sheet Metal - Kraus, Martin; Hufnagel, Thomas; Merklein, Marion (Journal of Micro and Nano-Manufacturing, 2019)
LFT Import::2019-07-29 (2357)

Accuracy of Conventional Finite Element Models in Bulk-Forming of Micropins from Sheet Metal - Kraus, Martin; Hufnagel, Thomas; Merklein, Marion (Journal of Micro and Nano-Manufacturing, 2019)
The ongoing miniaturization trend in combination with increasing production and functional volume leads to a rising demand for metallic microparts. Bulk forming of microparts from sheet metal provides the potential for mass production of those components by an extensive simplification of the handling. The advantage of a high production rate contrasts with the disadvantage of a low utilization of material. In this context, it is necessary to investigate suitable measures to increase the material utilization. To save cost intensive trial and error tests, numerical analysis could be an appropriate method for a basic process investigation. In this work, a validation with experimental results in the macro- and microscale was used to investigate the eligibility of the finite element method (FEM) for a basic process analysis. For a high transferability, the finite element (FE) models were validated for various tribological conditions and material states. The results reveal that there is a high agreement of the experimental and numerical results in the macroscale. In microscale, conventional FEM shows inaccuracies due to the negligence of size effects in the discretization of the process. This fact limits the application of conventional FE-programs. Furthermore, the results show that lubricated and dry formed blanks lead to the same friction force and process result in the microscale. In addition, the basic formability of the prestrengthened pins in further forming stages was experimentally demonstrated.
CRIS-Team Scopus Importer:2019-05-02
Keywords: bulk microforming; friction; Microforming; micropart; size effects; validation

A classification system for secondary design features for the use within sheet-bulk metal forming - Breitsprecher, Thilo; Wartzack, Sandro (Proceedings of the 19th International Conference on Engineering Design, 2013)
Estimating the potential of new emerging manufacturing technologies for the area of engineering design is crucial for the establishment of these processes in the industry sector. An example for such a new technology is sheet-bulk metal forming (SBMF): New parts can be designed due to the higher design freedom for design engineers and the possibility to integrate more functions by using more functional elements per part. Furthermore it is of high interest if this emerging technology can be used to substitute established manufacturing processes and produce parts with a higher functional density with less process steps and more robust processes. In this paper a new classification system is presented that enables the design engineer to classify parts with primary and especially secondary design features. On the one hand the classification system can be used to identify parts for which the established manufacturing process may be substituted by SBMF. On the other hand potential for new innovative solutions can be revealed.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.aclass
Keywords: Design for x; Feature classification; Information management; New product development; Sheet-bulk metal forming

A Comparative Study on Tolerance Analysis Approaches - Schleich, Benjamin; Anwer, Nabil; Zhu, Z.; Qiao, L.; Mathieu, Luc; Wartzack, Sandro (Proceedings of the International Symposium on Robust Design - ISoRD14, 2014)
Robust product designs are characterized by their insensitivity to disturbances and noise, such as geometric part deviations, which are inevitably observed on every manufactured workpiece. These observed deviations are covered by the axioms of manufacturing imprecision and measurement uncertainty, which convey the concepts of variability and uncertainty as fundamental aspects of robust design. In order to ensure the product function though the presence of these geometric part deviations without building physical artefacts, tolerance simulations are employed in the context of computer-aided tolerancing. Motivated by the shortcomings of existing tools, the concept of Skin Model Shapes has been developed as a novel paradigm for the computer-aided tolerance analysis. This paper presents a comparative study on the standard procedure for the tolerance analysis employing proprietary CAT tools and the tolerance simulation based on Skin Model Shapes. For this purpose, two exemplary study cases are highlighted. Based on the comparisons, general remarks on the use of CAT tools in the context of tolerance analysis and robust design are derived.
Keywords: Computer-Aided Tolerancing; Skin Model; Tolerance Simulation

A Comprehensive Framework for Skin Model Simulation - Schleich, Benjamin; Walter, Michael; Wartzack, Sandro; Anwer, Nabil; Mathieu, Luc (ASME 2012 11th Biennial Conference on Engineering Systems Design and Analysis, Volume 3: Advanced Composite Materials and Processing; Robotics; Information Management and PLM; Design Engineering, 2012)
The need for geometrical variations management is an important issue in design, manufacturing and all other phases of product development. Two main axioms cover geometrical variations, namely the axiom of manufacturing imprecision and the axiom of measurement uncertainty. Therefore, this paper reviews common models for the description of non-ideal geometry (shape with geometric deviations) and shows how the random field theory can be applied to create more realistic skin models (a model which comprises these geometric deviations). Furthermore, methods to estimate and to express the underlying random field from a sample population are shown. These can be used to create and simulate random shapes considering systematic and random deviations observed through measurement or gathered from manufacturing process simulations. The proposed approach incorporates given information from manufacturing process simulations or prototypes. Based on these information, skin model samples are created which can represent the "realistic" part in assembly simulations or other geometrical analyses. This can help to identify the optimal tolerance sets within every stage of the product development process. The efficiency of the introduced approaches is shown in a case study.
UnivIS-Import:2015-04-16:Pub.2012.tech.FT.FT-KLMEFK.acompr
Keywords: Geometric deviations; GPS; Random fields; Skin model simulation

A computational design approach for composite structures at the early embodiment design stage - Klein, Daniel; Malezki, Waldemar; Wartzack, Sandro (NAFEMS World Congress 2015, 21. - 24. Juni, San Diego, USA, NAFEMS World Congress, 2015)
The design of composite structures is a big challenge because a lot of different and mutually dependent parameters like the fiber orientation, the stacking sequence or the layer thicknesses have to be defined. Additionally, even small deviations of these parameters from the ideal can significantly reduce the mechanical properties of the composite part which makes the design of composite parts particularly challenging. Therefore, it is essential to use novel simulation tools and computational methods as soon as possible in the design process. However, many existing software tools are based on a sequence of complex optimization algorithms or are highly restricted, and therefore, not suitable for the early embodiment design of composite parts. Within the intended paper a novel simulation based design approach will be presented which offers a high freedom in design and is based on simple engineering considerations. The design approach can be divided into four different steps: Step 1: Modified Multi-Layer CAIO Method Step 2: Cluster-algorithm Step 3: Defining the stacking sequence Step 4: Compute layer thicknesses In the first step of the design approach the so called Modified Multi-Layer CAIO method is used to compute the ideal fiber orientations and stresses for each load case in an iterative process. As input for this method a FE model for each load case with an arbitrary number of layers and fiber orientation is created and each model is solved separately. For each model the mean stress directions are computed and the elemental fiber orientations in the FE models are oriented in direction of the maximum mean stresses. These modified models are solved again and the process is repeated as long as there is a significant change in the mean stresses. Based on the results of the Modified Multi-Layer CAIO, the number of layers for each finite element as well as the needed fiber orientations can be computed. However, since every element can have a different fiber orientation and number of layers, the computed laminate structure is not manufacturable. For this reason, a cluster algorithm is needed (step 2) to find areas with equal fiber orientation and, therefore, areas where patches could be placed. The basic principle of the cluster algorithm is to choose a first layer of an arbitrary starting element and compare the fiber orientations of this layer to all layers in the neighboring elements. If the comparison of the fiber orientations is positive the neighboring layer is added to the first cluster. For this grown cluster again all the neighboring elements are checked and the comparison process repeats until no new layer can be added to the existing cluster. In this case a new starting element is chosen and the procedure starts again to form a new cluster.  In the end, the clusters are highlighted and a possible patch structure is shown which helps product developers to define a first laminate. However, the ideal stacking sequence as well as the thickness of each layer is still unknown at this stage. Therefore, steps three and four have to follow. In step three the stacking sequence is defined with the help of the stresses which were computed in step 1. The fiber orientations of the patches are compared to the mean stresses in each of the arbitrary layers and a value for the overlapping is computed in each position. The stacking sequence with the highest overall overlapping value is chosen. In the last step (step 4), a FE model is created with the computed stacking sequence and the thicknesses are defined with a simple genetic algorithm.
UnivIS-Import:2015-10-26:Pub.2015.tech.FT.FT-KLMEFK.acompu
Keywords: Composites; Leichtbau; Simulation

A concept and prototype for a new app to support collaborative and multi-criteria decision making in product development - Luft, Thomas; Rupprecht, Simon; Wartzack, Sandro (DS 87-1 Proceedings of the 21st International Conference on Engineering Design (ICED17), Vol. 1: Resource-Sensitive Design, Design Research Applications and Case Studies, 2017)
As products become increasingly complex, product developers have to make decisions effectively and efficiently. Therefore, the long term goal of the authors is the development of a new app to support collaborative and multi-criteria decision making in product development. For this, the basic requirements of such a new app are presented. Based on this, the methodological concept and procedure are briefly explained. Afterwards, a first prototype of the app with the core functionalities and the user interface is presented. Finally, this prototype is applied and evaluated by an example. In the future, the authors aim to improve the concept and to integrate further functionalities by implementing the presented concept as a real smartphone app.
Keywords: Decision making; Evaluation; Collaborative design; Decision-making app; Design management

A concept for a novel hybrid augmented reality computer workstation for virtual product development - Harlan, Jakob; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the 33rd Symposium Design for X (DFX2022), 2022)
Extended reality user interfaces for engineering design often suffer from gaps in the user’s workflow. Usually, the user must at least put on hardware, but often also data preparation is needed. This research aims to close these gaps by proposing a setup fusing desktop and immersive user experience into a hybrid augmented reality computer workstation. Here the user can decide for each operation what modality is best suited, using the strengths of both interfaces while avoiding their drawbacks. In this paper, a concept for such a hybrid computer workstation is developed using the morphological matrix method. Different solutions for the main features, holographic stereo display, spatial interaction, and the software architecture, are discussed and a reasoned combination is proposed as a feasible concept.<br
Keywords: CAD; Augmented Reality; Product Design; Morphological Matrix; Computer workstation

A concept for FE plausibility checks in structural mechanics - Sprügel, Tobias; Hallmann, Martin; Wartzack, Sandro (Summary of Proceedings, 2015)
The finite element method is, alongside with CAD, one of the most efficient tools for optimizing the quality of engineering tasks (Klein 2010). Furthermore, the currently available FE software is getting more and more user friendly. However, especially less experienced users - such as designers - perform more and more FE simulations but do not have the knowledge of experienced computation engineers. Often these users do not have a complete overview of the performance of currently used simulation and calculation tools for securing product and also manufacturing process characteristics. However it is highly essential to optimize the quality and minimize the costs of a technical design as early as possible during the product development process. Therefore, these users need to be assisted when performing simulation tasks. This can be achieved by an integrated plausibility check in the postprocessing of the FE software. When an existing FE result data set is checked for plausibility further steps towards a better assistance for part time users can be taken. Such as an error assistant for implausible results or a context-sensitive result visualization to help the user to understand the simulated results. The presented approach in this paper is part of the Bavarian Research Cooperation FORPRO² for efficient product and process development by knowledge based simulation. The aim of the Research Cooperation is to increase efficiency of virtual product and process development through the creation of an expert knowledge based simulation framework for property optimization and quality improvement of new products. The expected result 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. Within the Research Cooperation an FEA-assistance system with an integrated plausibility check is developed. In this paper an approach for plausibility checks applicable for different standard components with mathematical meta-models is presented. At first the terms plausibility, verification and validation are distinguished. Then different meta-models and their requirements and possibilities for evaluating the quality are shown. The paper closes with an exemplary application – a piston pin of a combustion engine, for which a plausibility check with different mathematical meta-models is demonstrated.
UnivIS-Import:2015-10-26:Pub.2015.tech.FT.FT-KLMEFK.aconce
Keywords: plausibility checks; FEM; structural mechanics; meta-models; RSM; ANN

A Concept for Physiological User Description in the Context of Dual User Integration - Schröppel, Tina; Diepold, Theresia; Miehling, Jörg; Wartzack, Sandro (Proceedings of the 22nd International Conference on Engineering Design (ICED19), 2019)
In order to ensure the user's acceptance towards a product, the user has to be captured with all his facets and requirements. In this context, many user-centred design methods only focus on single aspects such as subjective expectation or ergonomic product design. Correlations and connections or a common consideration of several user parameters are often neglected, even if this can provide useful information for improving the design of products. Dual user integration tries to close this gap to a certain extent and considers the user's subjective expectation in combination with their physiological capacities. An integral part of this approach is a target-oriented evaluation of the user. Currently available methods of physiological and subjective evaluation of the user are only partially applicable for dual user integration. Especially physiological measurement techniques are time-consuming and expensive. For this reason, this contribution presents a new concept for capturing and describing the physiological capacity of the user via semantic differentials. Thereby, motor functions, cognition and perception are considere
Keywords: User centred design; Design methods; Integrated product development; Dual user integration; Physiological user description

A concept for process-oriented interdisciplinary tolerance management considering production-specific deviations - Heling, Björn; Oberleiter, Thomas; Rohrmoser, Andreas; Kiener, Christoph; Schleich, Benjamin; Hagenah, Hinnerk; Merklein, Marion; Willner, Kai; Wartzack, Sandro (Proceedings of the 22nd International Conference on Engineering Design (ICED19), 2019)

A Concept for the Consideration of Dimensional and Geometrical Deviations in the Evaluation of the Internal Clearance of Roller Bearings - Aschenbrenner, Alexander; Wartzack, Sandro (Procedia CIRP, 2016)
Internal clearance is a functional key characteristic of bearings. The bearing clearance can be evaluated using rigid body movements of the inner ring. Due to the deviations of dimension and roundness the contact areas between the bearing components cannot be predicted. Hence contact detection is necessary. For this purpose the herein presented concept is based on a raytrace algorithm. The concept can be used for the simulation of the bearing clearance for deviated bearing components. This enables the evaluation of the influence of dimensional and form deviations on the bearing clearanc
Keywords: tolerance simulation; bearing clearance; dimensional deviation; deviation of roundness; contact detection

A Concept Towards Automated Reconstruction of Topology Optimized Structures Using Medial Axis Skeletons - Mayer, Johannes; Wartzack, Sandro (Proceedings of the Munich Symposium on Lightweight Design 2020, 2021)
Through continuous topology optimization the design within modern product development of structural loaded components can be enhanced by using maximized lightweight potential. At the same time the product development pro-cess is accelerated due to a reduced number of design cycles. Because topology optimization yields an optimized material distribution, the designer is not re-quired anymore to iteratively work out the principal geometric shape. How-ever, optimized material distribution itself neither follows design rules, nor does it pro-vide parametric relations within parts. Instead, a redesign has to be done in order to fulfill manufacturing requirements and to obtain a parametric CAD-model. This usually takes a lot of effort in time and expert knowledge. For the reason of a consistent development approach under assistance of com-puter aided methods, a concept is presented, that is demanded to solve the task of redesigning topology optimization results in parametric CAD-models in a semi-automated manner. To achieve this, medial axis skeletons are used for analyzing the geometric data of optimization results. In a second step, the skeletons are used for rebuilding parametric CAD-models. They are taken as references for common CAD-functionality whereby a parametric and history based modeling structure are generated.<br
Keywords: Topology Optimization; Medial Axis Skeleton; CAD

A CONCEPTUAL MODEL COMBINATION FOR THE UNIFICATION OF DESIGN AND TOLERANCING IN ROBUST DESIGN - Grauberger, Patric; Götz, Stefan; Schleich, Benjamin; Gwosch, Thomas; Matthiesen, Sven; Wartzack, Sandro (Proceedings of the Design Society: DESIGN Conference, 2020)
In design engineering, the early consideration of tolerance chains contributes to robust design. For this, a link of design and tolerancing domains is essential. This paper presents a combination of the graph-based tolerancing approach and the Contact and Channel approach to link these domains. The combined approach is applied at a coinage machine. Here it provides detailed insights into state-dependent relations of embodiment and functions, which can improve robustness evaluation of the concept. This approach shows a possibility to bridge the gap between design and tolerancing domains.<br
Keywords: Engineering design; Modelling; Tolerance representation and management; Robust design

A contact model to simulate human–artifact interaction based on force optimization: implementation and application to the analysis of a training machine - Krüger, Daniel; Wartzack, Sandro (Computer Methods in Biomechanics and Biomedical Engineering, 2017)
Musculoskeletal multibody models are increasingly used to analyze and optimize physical interactions between humans and technical artifacts. Since interaction is conveyed by contact between the human body and the artifact, a computationally robust modeling approach for frictional contact forces is a crucial aspect. In this contribution, we propose a parametric contact model and formulate an associated force optimization problem to simultaneously estimate unknown muscle and contact forces in an inverse dynamic manner from a prescribed motion trajectory. Unlike existing work, we consider both the static and the kinetic regime of Coulomb’s friction law. The approach is applied to the analysis of a leg extension training machine with the objective to reduce the stress on the tibiofemoral joint. The uncertainty of the simulation results due to a tunable parameter of the contact model is of particular interest.
Keywords: musculoskeletal simulation; contact modeling; optimization; device design

A Co-Simulation Model Integrating a Musculoskeletal Human Model with Exoskeleton and Power Tool Model - Molz, Carla; Scherb, David; Löffelmann, Christopher; Sänger, Johannes; Yao, Zhejun; Lindenmann, Andreas; Matthiesen, Sven; Weidner, Robert; Wartzack, Sandro; Miehling, Jörg (Applied Sciences, 2024)
Working at and above head height with a power tool represents a common activity in craft and assembly applications. To assist and protect the user from overload and injuries in these situations, the development and use of application-specific support systems, such as exoskeletons and power tools, have greatly increased in recent years. Thus, the integration of aspects of the user-centered product development of support systems in the early phases of product development process has high potentials. A common approach to integrate the user early in the product development process is the use of musculoskeletal human models, which allow the evaluation of effects on the human body. This could also be applicable in the mentioned use case to enable the evaluation of the interactions for the user. Therefore, a co-simulation model for virtual modelling and simulating human–machine interactions is presented. The co-simulation model is made up of a musculoskeletal human model and the models of the technical systems (exoskeleton and power tool). By applying the co-simulation model, the impact of technical systems on the human body can be taken into account to derive design alternatives for the technical system due to the requirements of the user. The paper describes the design of the co-simulation model and particularly, the interaction of the submodels. The evaluation of the co-simulation model is carried out with the help of a subject study for the selected use case working at and above head height. The results show plausible results for the muscle loads considering the support by an exoskeleton. Furthermore, the comparison of simulated results to measured muscle activations via surface electromyography shows a good agreement. Thus, the co-simulation model passes the test for functionality and seems to be applicable for the derivation of design alternatives of technical systems regarding the user needs. In future, the co-simulation model will be further validated with a higher number of subjects and to implement design alterations in the technical systems.<br
Keywords: human–machine interaction; biomechanics; support systems; exoskeleton; product development; user-centered design; musculoskeletal human model

Acquisition of design-relevant knowledge within the development of sheet-bulk metal forming - Röhner, Sebastian; Breitsprecher, Thilo; Wartzack, Sandro (Proceedings of the 18th International Conference on Engineering Design 2011 (ICED11), 2011)
The increasing requirements on technical products represent a growing challenge for the manufacturing engineering. This challenge will be met by the development of a new manufacturing technology called sheet-bulk metal forming. For the early consideration of the full potential of sheetbulk metal forming in a design process, a design engineer has to know the process limitations as soon as possible. Hence, the objective has to be to acquire design-relevant knowledge already in the early phases of process development and to maintain this knowledge simultaneously to the further development of the process. These are the declared aims of the self-learning engineering assistance system that will carry out the acquisition and maintenance of knowledge owing to its self-learning aspect. In this article, within an evaluation of knowledge acquisition methodologies, data mining was identified as a possibility for the realization of the self-learning aptitude. The potential of data mining was shown by its application on simulation data to acquire design-relevant knowledge. Copyright © 2002-2012 The Design Society. All rights reserved.
UnivIS-Import:2015-04-16:Pub.2011.tech.FT.FT-KLMEFK.acquis
Keywords: Data Mining; Knowledge Acquisition; Sheet-Bulk Metal Forming

Acquisition of heuristic knowledge for the prediction of the frictional behavior of surface structures created by self-excited tool vibrations - Breitsprecher, Thilo; Hense, R.; Hauer, Franz; Wartzack, Sandro; Biermann, Dirk; Willner, Kai (Key Engineering Materials, 2012)
The selective control of the frictional behavior (tailored friction) in metal forming processes is of high importance with regard to technical and economic aspects. This applies especially for the sheet-bulk-metal forming process. Milling with intentionally invoked regenerative tool vibrations can be applied in order to generate structured surfaces with tailored friction properties on the forming tool. These structures affect the formation of lubrication pockets during the forming process which determine the local frictional properties exceedingly. The full potential of this emerging technology can, however, only be revealed if the heuristic and design-relevant knowledge is acquired and provided to the tool-designer already in the early phases of process development. One thing the tool-designer has to specify is the local frictional behavior on the tool surface. But, however, he does not know which milling parameters lead to the necessary surface structures because in most cases he has no expert knowledge in milling, tribology and forming tools. In this paper data mining is used to determine the frictional behavior based on these parameters. The potential of this method in the described context is revealed by the application on data derived from simulation results, both from milling simulations and contact simulations. The latter are performed by using a Halfspace model for rough surface contact. Both approaches for these simulations, the data mining process and the results are explained to the reader.© (2012) Trans Tech Publications.
UnivIS-Import:2015-03-09:Pub.2012.tech.FT.FT-KLMEFK.acquis
Keywords: Data mining; Halfspace model; Milling with vibrations; Self-learning system

Active Vibration Control of Excited Structures by means of Shape Adaption - Nowak, Alexander; Willner, Kai; Campanile, Lucio Flavio; Hasse, Alexander (International Conference on Adaptive Structures and Technologies, 2017)

Adapting FE-Meshes to real, 3D surface detected geometry data to improve FE-simulation results - Katona, Sebastian; Sprügel, Tobias; Koch, Michael; Wartzack, Sandro (Summary of Proceedings, 2015)
Today’s product development process is picking up the pace. To avoid performing complex and expensive testing including all iterations of the product development with a real prototype, various FE-simulations (finite element) for the functional validation of the desired characteristics are made. The discretization of a developed component and the use of the simulation conditions, like taking different non-linearities (i.e. material behavior, contact situations, large deflections etc.) into account, is a tremendous effort and is necessary to get precise and significant results. In general, every constructed component shows differences to its ideal geometry of the designed CAD-model (Computer Aided Design), i.e. due to deformations in the production process. Depending on the manufacturing process, random deviations and the component size, these differences can vary. In cutting processes the value is relatively small, but using forming (i.e. deep-drawing or bending) and casting techniques (i.e. die casting or injection molding) process-related effects like spring back and shrinkage or warpage occur and can trigger bigger deformations. Despite knowing the effects of deformations, due to the production process mentioned above, the product developer always uses the non-deformed design model of a CAD-system for the FEsimulation of a component. It seems rather doubtful that further refinement of simulation methods makes sense, if the real manufactured geometry of the component is not considered for in the simulation. For an efficient exploit of the potential of simulation methods, an approach has been developed which offers a geometry model for simulation based on the existing CAD-model but with integrated production deviations as soon as a first prototype is at hand. Thus, a functional validation of the real geometry can easily be performed. The approach in this article is to detect the occurring deformations of a near-series produced prototype with a high-resolution optical measuring instrument and to use that data for simulation purposes. The whole reverse engineering (RE) process including data preparation, complex surface reconstruction and furthermore a complete new simulation preprocessing is omitted due to lack of capacity. Therefore, the detected data (either point cloud or polygonal model) is used directly for the creation of an adapted FE mesh. The presented method describes an opportunity to automatically adapt existing FE-meshes, generated with the non-deformed CAD-model, to the deviated geometry caused by production. Thereby 3d surface scans and relevant algorithms are used. Therefore, the surface nodes are extracted from an ANSYS input file. A measurement of the deviation to the scanned model at each node position (point cloud or polygonal model) takes place by using a comparison point within the software PolyWorks. Afterwards a preload-step is defined, in which the deviation of every surface node is applied as a displacement. The mesh emerging from this preload-step with its new nodes coordinates is the basis for further simulations with real geometry. Herewith, a completely new input file with the new mesh and the identical content of the initial input file based on the ideal CAD-model (considering material definition, forces, boundary conditions etc.) is created. As a result, an FE-model with real geometry is available and can be used directly for a simulation without spending a lot of time on additional preprocessing. The advantage can be seen in the omission of a complex creation of a new model for simulating the real manufactured geometry. Comparative analysis between ideal and real geometry is simple, when using this approach in the product development process.
UnivIS-Import:2015-10-26:Pub.2015.tech.FT.FT-KLMEFK.adapti
Keywords: FEA (finite element analysis); preprocessing; simulation; 3D surface detection; RE (reverse engineering)

Adaption of tribological behavior of a-C:H coatings for application in dry deep drawing - Häfner, Tom; Rothammer, Benedict; Tenner, Jennifer; Krachenfels, Kim; Merklein, Marion; Tremmel, Stephan; Schmidt, Michael; Schmidt, Michael (MATEC Web of Conferences, 2018)
Nowadays the sheet metal forming industry faces challenges regarding efficient usage of resources and sustainability. One strategy to increase the environmental friendliness is to abandon the application of lubricants. The direct contact between tool and workpiece leads to an intensive interaction which increases friction. Especially for deep drawing processes with long sliding distances, this causes distinctive wear. The tool sided application of carbon based coatings is a well-known approach to reduce friction and wear. Former studies have shown a beneficial behavior of hydrogenated amorphous carbon based coatings (a-C:H) to improve the tribological conditions in contact with steel sheets and aluminium alloys under dry conditions. Within this study the coating process and the resulting coating properties will be analyzed. Afterwards mechanical and laser based surface treatment processes prior and after the deposition process will be investigated to reduce the coating roughness. Different roughness values were achieved by varying the surface treatment processes. The laser based finishing enables a reduction of the Spk values by removing single roughness asperities. In order to identify the necessary process parameters for the laser treatment, an analytical model of the material removal was applied. The laser surface treatment achieved similar roughness characteristics compared to mechanical treatment. In this study the tribological behavior of a-C:H coated tools was analyzed under dry conditions within strip drawing tests. The tribological investigations revealed that for dry deep drawing of zinc coated DC04 a broader range of Spk values leads to acceptable tribological conditions whereas for AA5182 a smoother tool surface has to be ensured to prevent adhesion and utilize the full potential of a-C:H coatings.<br
Keywords: Tribology; Surface Modification; Dry Deep Drawing

A data model for linking testbed and field test data - Sauer, Christopher; Schleich, Benjamin; Wartzack, Sandro (32nd Symposium Design for X (DFX2021), 2021)
With the help of data-driven methods such as machine learning, the development of the current product generation can be supported and improved through the early use of data from previous products and product generations. For example, machine learning can be used to predict later product behaviour in field tests from testbed data. This can significantly shorten the development time and save expensive field tests. To implement this data provision for the development processes, uniform data models enable the use of data-driven methods and are of central importance. This paper presents a data model using the example of a testbed for electric vehicle transmissions. Here, potentials for a later data-driven prediction of the product behaviour in the field test for the optimisation of the existing development are shown
Keywords: Graph databases; machine learning; digital engineering

A discrete geometry approach for tolerance analysis of mechanism - Schleich, Benjamin; Wartzack, Sandro (Mechanism and Machine Theory, 2014)
Tolerance analysis aims at predicting the effects of inevitable geometric deviations on the quality and function of mechanical products and is therefore an import tool in the design and dimensioning of mechanism. Since geometric deviations have various sources, different simulation tools and computer-aided engineering applications must be applied to determine them. Most of these tools are based on a surface or volume discretization, which leads to a workpiece representation in discrete geometry. In this contribution, an approach for the tolerance analysis of mechanism employing these discrete geometry representations is proposed. It is based on the processing of non-ideal workpiece representatives and helps to incorporate results from different validation applications. The approach is applied to the tolerance analysis of spur gears by employing a Tooth Contact Analysis algorithm.
Keywords: Tolerance analysis; Tooth Contact Analysis; Discrete geometry

A Fracture mechanically based strength analysis of planet carriers for wind turbines made of high strength cast iron - Broeckmann, Christoph; Keusemann, Santino; Özden, Utku Ahmet; Bartz, Marcel; Krull, Frank; Langenberg, Peter (Tagungsband CWD 2013: 1st Conference for Wind Power Drives,, 2013)

A function-oriented surface reconstruction framework for reverse engineering - Qie, Yifan; Bickel, Sebastian; Wartzack, Sandro; Schleich, Benjamin; Anwer, Nabil (CIRP Annals - Manufacturing Technology, 2021)
Reverse engineering can be considered as the methodological process of analyzing and reconstructing a digital model of a physical asset. It has gained considerable interest with the advent of sophisticated sensors and data processing technologies hence becoming an important enabler for the product digital twin. However, while existing approaches to reverse engineering focus on the mere geometric reconstruction, this paper presents a novel paradigm called function-oriented surface reconstruction, that is capable of reconstructing the underlying part and surface function and thus outperforms existing methods. The applicability of the presented method is demonstrated through a case study of a gearbox.
CRIS-Team Scopus Importer:2021-05-21
Keywords: Data-driven design; Machine learning; Reverse engineering

A Generic Approach to Sensitivity Analysis in Geometric Variations Management - Schleich, Benjamin; Wartzack, Sandro (Proceedings of the 20th International Conference on Engineering Design (ICED 15) Vol 4: Design for X, Design to X, 2015)
Engineering design teams are increasingly required to consider sustainability in the design of products and related manufacturing and assembly processes. In this regard, the economic and ecological sustainability of products as well as their quality and cost is influenced by geometric part deviations, which are inevitably observed on every manufactured artefact. Thus, the management of geometric deviations along the product lifecycle is a key issue for companies to living up to modern innovation requirements. The aim of this paper is to provide an overview of tools for the tolerance analysis in different stages of geometric variations management and to propose a versatile approach for the sensitivity analysis applicable in these different stages. This approach is to support decision making in the geometric variations management during integrated product and process design.
UnivIS-Import:2015-10-26:Pub.2015.tech.FT.FT-KLMEFK.agener
Keywords: Robust Design; Tolerance Representation And Management; Decision Making

A haptic based Hybrid Mock-Up for mechanical products supporting human-centered design - Krüger, Daniel; Stockinger, Andreas; Wartzack, Sandro (Proceedings of the 18th International Conference on Engineering Design (ICED 11) Vol. 10, 2011)
The overall goal of the design process is to create products of good usability. A human-centered design process is characterized by a continuous involvement of the prospective user of the product. This also comprises user-based concept assessments and design optimizations. For this purpose in many cases it is necessary that the user is given the possibility to perceive the product emotionally. Thus the flexibility of digital mock-ups well established in digital engineering can't be used. Instead, physical prototypes are often indispensible. In this paper a Hybrid Mock-Up approach is presented that allows a physical interaction with virtual prototypes. The behavior of the product is simulated digitally whereas elements of the human-machine interface are emulated using a generic haptic device. The benefit of the approach is that for the user a realistic product perception is achieved without having to dispense with the advantages digital engineering offers: saving of costs and time due to a reduction of physical prototypes. The approach is illustrated in a case study of a crank driven car jack.
UnivIS-Import:2015-04-16:Pub.2011.tech.FT.FT-KLMEFK.ahapti
Keywords: Computer haptics; Design space exploration; Human-centered design; Hybrid mock-up

A Hierarchical Approach for the Verification and Validation of Tolerance Analysis Models - Schächtl, Paul; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the ASME 2022 International Mechanical Engineering Congress and Exposition (IMECE2022), 2023)
Established tolerance analysis methods are capable of predicting the effects of geometrical part variations on the quality of products and hence virtually assuring their functionality. However, assumptions and simplifications are often made, which can lead to decisive uncertainties. To omit a significant effect of these uncertainties on the overall model and on the obtained results, both a virtual assessment of the model as well as an experimental validation are necessary. The current state of the art still lacks suitable methods and metrics to reliably evaluate the results of tolerance analyses. In addition, an approach is needed to investigate and evaluate the effects of uncertainties within the analysis model on the overall model. The aim of this contribution is therefore to derive statements about the suitability and significance of methods and metrics of verification and validation for evaluating simulation models and their feasibility in the context of tolerance analysis. First, general methods and metrics for the evaluation of simulation results are presented. Subsequently, the most promising ones are customized in an unifying approach. The statistical tolerance analysis of a 3-D-printed non-assembly mechanism in motion serves as an explanatory example for highlighting the procedure and the current challenges and constraints. Finally, the findings are critically discussed and as a result, statements about the further need for action are presented.<br
Keywords: Verification & Validation; Tolerance Analysis

A holistic decision making process for awarding development projects to external service providers - Bausewein, Natascha; Luft, Thomas; Thater, Gerald; Wartzack, Sandro (11. Gemeinsames Kolloquium Konstruktionstechnik 2013: Standortvorteil Methodik, 2013)
Particular challenges faced by the automotive industry are the increasing product variety and complexity caused by customer requirements in terms of individualization. The resulting large number of development projects can often not be realized in particular by small and medium enterprises due to staff shortages. In case of resource bottlenecks companies have the option to award projects to external service providers. The goal of the present paper is to define a holistic decision making process for awarding development projects because of staff shortages. For this purpose an appropriate and detailed process will be developed that standardizes the outsourcing procedures and provides methodological support for practical use. As a result, critical factors will be considered and consequently the success rate of awarding projects will be increased. Finally, the suitability of the proposed approach is validated in an industrial case study.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.aholis
Keywords: development service; awarding development projects; outsourcing; decision making; evaluation methods; methodologies for small and medium enterprises

AI4PD—Towards a Standardized Interconnection of Artificial Intelligence Methods with Product Development Processes - Gerschütz, Benjamin; Götz, Stefan; Wartzack, Sandro (Applied Sciences, 2023)
The transformation of virtual product development to Digital Engineering (DE) requires the successful integration of Digital Engineering or data-driven methods into existing product development processes. Those methods allow for the analysis and usage of existing data. However, missing knowledge about these methods, as well as their performance or limitations, is a major burden for their application, especially in small and medium-sized enterprises. In order to close this gap, this paper proposes the AI4PD ontology, linking product development processes (PD) and Digital Engineering methods (AI). This knowledge representation gives companies an overview of the available methods to support them in selecting a suitable solution for their problems. The representation of AI4PD is performed in Protégé using the W3C standard OWL syntax. The opportunities of AI4PD are shown by a use case of identifying a DE-Method for predicting manufacturing possibilities based on test data and CAD files. Furthermore, after possible problems in existing product development processes are identified, AI4PD covers the necessary knowledge for a successful method of identification and integration to transform virtual product development to Digital Engineerin
Keywords: ontology; digital engineering; artificial intelligence; product development; formalisation; knowledge reuse; knowledge representation

A knee simulator pilot study: Performance of amorphous carbon coated articulating surfaces for total knee replacement - Rothammer, Benedict; Neusser, Kevin; Bartz, Marcel; Wartzack, Sandro; Kistler, Manuel (65. Tribologie-Fachtagung. Reibung, Schmierung und Verschleiß. Forschung und praktische Anwendungen., 2024)
Experimental in vitro testing of the implants was performed in a knee simulator according to ISO 14243-1. The wear mass of the tibial inlay was determined gravimetrically with an analytical balance. By coating both articulation partners, a reduction in the wear mass of 57% compared to CoCr/CPE and 62% compared to Ti64/CPE could be achieved.<br

A knowledge-based engineering workbench for automated tolerance specification - Sauer, Christopher; Heling, Björn; Schmutzler, Simon; Schleich, Benjamin (ASME 2019 International Mechanical Engineering Congress and Exposition, 2019)
Designers often lack important information about achievable manufacturing tolerances. Moreover tolerances are not considered from the beginning of product development. This often leads to inaccurately specified parts. Furthermore the full potential of the manufacturing departements is not used. This contribution tackles those areas by presenting a knowledge-based engineering workbench for automated tolerance specification, which has also been implemented using a commercial CAD system. This tool allows the designer to assign part tolerances that take into account the achievable accuracies for a specific manufacturing process, while at the same time allowing for specific part properties. The novelty of the presented approach can be found in the knowledge-based support of the product developers in tolerance specification by employing an engineering workbench. Moreover preprocessing for variation simulation and analysis is supported. It is possible to automate parts of the tolerance specification process, using the presented approach.<br
Keywords: engineering workbench; computer aided tolerancing

A Literature Review on the Development and Creation of Digital Twins, Cyber-Physical Systems, and Product-Service Systems - Fett, Michel; Wilking, Fabian; Götz, Stefan; Kirchner, Eckhard; Wartzack, Sandro (Sensors, 2023)
Digital Twins offer vast potential, yet many companies, particularly small and medium-sized enterprises, hesitate to implement them. This hesitation stems partly from the challenges posed by the interdisciplinary nature of creating Digital Twins. To address these challenges, this paper explores systematic approaches for the development and creation of Digital Twins, drawing on relevant methods and approaches presented in the literature. Conducting a systematic literature review, we delve into the development of Digital Twins while also considering analogous concepts, such as Cyber-Physical Systems and Product-Service Systems. The compiled literature is categorised into three main sections: holistic approaches, architecture, and models. Each category encompasses various subcategories, all of which are detailed in this paper. Through this comprehensive review, we discuss the findings and identify research gaps, shedding light on the current state of knowledge in the field of Digital Twin development. This paper aims to provide valuable insights for practitioners and researchers alike, guiding them in navigating the complexities associated with the implementation of Digital Twins.<br
Keywords: Digital Twin; Cyber-Physical System; development; review; methods

A Machine Learning-Based Approach for Quick Evaluation of Live Simulations in Embodiment Design - Sauer, Christopher; Gerschütz, Benjamin; Bernsdorf, Jörg; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the Design Society, 2022)
Supporting product developers in early design phases with Live-Simulation can enhance the quality of early product designs. Live-Simulation can also facilitate a democratization of simulation and puts away pressure from simulation experts. In this paper, a machine learning based quick evaluation tool is proposed to support product developers in interpreting Live-Simulation results. The proposed tool enables a quick evaluation of the Live-Simulation results and enables product developers to further enhance their simulations. The tool is shown within a use case in bike rocker switch design.<br
Keywords: data-driven design; simulation-based design; structural analysis; machine learning; live-simulation

A Method for Analyzing the Influence of Process and Design Parameters on the Build Time of Additively Manufactured Components - Hallmann, Martin; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the 22nd International Conference on Engineering Design (ICED19), 2019)
When using additive manufacturing processes, the choice of the numerous settings for the process and design parameters significantly influences the build and production time. To reduce the required build time, it is useful to adapt the parameters with the greatest influence. However, since the contribution of the individual parameters is not readily apparent, a sensible choice of process and design parameters can become a challenging task. Thus, the following article presents a method, that enables the product developer to determine the main contributors to the required build time of additively manufactured products. By using this sensitivity analysis method, the contributors of the individual parameters can be analyzed for a given parametrized CAD model with the help of an analysis-based build time estimation approach. The novelty of the contribution can be found in providing a method that allows studying both design and process parameters simultaneously, taking the machine to be used into account. The exemplary application of the presented method to a sample part manufactured by Fused Deposition Modeling demonstrates its benefits and applicabilit
Keywords: Additive Manufacturing; 3D printing; Design for Additive Manufacturing (DfAM); Sensitivity analysis; Analysis-based build time estimation

A Method for the Tolerance Analysis of Bearing Seats for Cylindrical Roller Bearings in respect to the Operating Clearance and the Fatigue Life - Aschenbrenner, Alexander; Wartzack, Sandro (DS 87-4 Proceedings of the 21st International Conference on Engineering Design (ICED 17), Vol 4: Design Methods and Tools, 2017)
Roller bearings are used in a vast variety of mechanical applications and are often highly stressed machine elements. Therefore the fatigue life of roller bearings can determine the reliability and service life of these mechanical systems. The fatigue life of a roller bearing is greatly affected by its operating clearance and the design of the adjacent components (namely shaft and housing). Especially the geometric dimensioning and tolerancing of the bearing seats can have great influence on the operating clearance and therefore the fatigue life of a roller bearing. In this article a method for the statistical tolerance analysis of the operating clearance of cylindrical roller bearings is presented. The method uses a discrete geometry representation coupled with contact detection algorithms for the determination of the operating clearance. The results are thereafter coupled with the calculation of the fatigue life. Statistical analysis of the results assists an engineering designer when choosing a robust design for the bearing seats.
Keywords: Tolerance representation and management; Robust design; Uncertainty; Cylindrical roller bearing

A methodical approach to model and map interconnected decision making situations and their consequences - Luft, Thomas; Schneider, Samuel; 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)
As products become more and more complex and have to be developed in less time, decision makers are facing the need to achieve good decisions efficiently. While some of the decision making processes are easy to undergo and their respective consequences can be identified with precision, other decision situations are characterized by complex steps and by consequences which are hard to predict. Therefore, the objective of this paper is to identify, analyze and evaluate conflicting decision making situations whose consequences are difficult to predict. The goal is to elaborate on a methodology in order to categorize and structure decision making situations and their respective consequences. This methodology is intended to support decision makers in evaluating decision making situations with regard to their interconnectivity and potential consequences. Future steps are the application of the overall methodology in a case study and its improvement due to the lessons learned.
UnivIS-Import:2015-10-26:Pub.2015.tech.FT.FT-KLMEFK.ametho
Keywords: Decision making; Decision making process; Decision consequences; Design methods; Process modelling

A methodology for the application of virtual evaluation methods within the design process of cold forged steel pinions - Rohrmoser, Andreas; Heling, Björn; Schleich, Benjamin; Kiener, Christoph; Hagenah, Hinnerk; Wartzack, Sandro; Merklein, Marion (Proceedings of the 22nd International Conference on Engineering Design (ICED19), 2019)

A model-based approach for early robustness evaluation – Combination of Contact and Channel Approach with tolerance graphs in SysML - Horber, Dennis; Li, Jiahang; Grauberger, Patric; Schleich, Benjamin; Matthiesen, Sven; Wartzack, Sandro (Proceedings of the 33rd Symposium Design for X (DFX2022), 2022)
Considering variations is essential for the development of robust products, but the applicability of existing robust design approaches in early stages is challenging due to the lack of product information and high levels of abstraction. To overcome this, a combined model is presented, which enables a holistic robustness evaluation in a linked approach. This approach uses the contact and channel approach to identify the relations between embodiment and functions as well as the robustness evaluation based on tolerance graphs. The combined model is implemented with the Systems Modeling Language (SysML) and applied to a coining machine use case. An initial assessment of the model combination and a proposal for a methodically supported workflow for the holistic robustness evaluation is give
Keywords: Robust Design; Variation Management; Contact and Channel Approach; SysML; Model-based Development

A Model-Based Approach for Integrated Variation Management - Horber, Dennis; Götz, Stefan; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the ASME 2022 International Mechanical Engineering Congress and Exposition (IMECE2022), 2023)
Variation management is a responsible task for product developers, which have to balance the ever-increasing quality demands and cost pressures, while considering the product design as well as the manufacturing and assembly process. These aspects have a direct impact on its subsequent success in the market. Therefore, a large number of different activities of variation management are necessary. In this area, a wide variety of mostly document-centered methods support product developers, which have individual interfaces. Thus, it is currently not possible to map the entire variation management process in a single model. Especially with regard to the increasing availability of large amounts of data, the potential of an integrated variation management cannot be exploited efficiently. For this reason, this paper presents a novel model-based approach for the development of a combined system and tolerancing model. This model contains the processes and activities of integrated variation management and links them with further system models and the corresponding data. The presented approach is a superordinate model for variation management as well as its processes and provides the modeling of individual views of different stakeholders. In addition, process- and program-specific solutions can be integrated into the model, which enables a cross-linking of the data beyond their interfaces. In this paper, the approach is realized using the systems modeling language (SysML
Keywords: integrated variation management; model-based systems engineering; process modelling; change effects

A modified approach for simulating complex compound structures within early design steps - Gruber, Georg; Klein, Daniel; Wartzack, Sandro (8th European LS-DYNA Users Conference, 2011)
UnivIS-Import:2015-04-16:Pub.2011.tech.FT.FT-KLMEFK.amodif_7

A modified scratch test for the mechanical characterization of scratch resistance and adhesion of thin hard coatings on soft substrates - Sander, Thomas; Tremmel, Stephan; Wartzack, Sandro (Surface & Coatings Technology, 2011)
The scratch resistance of coatings and the adhesion between coating and substrate are usually determined in model experiments performed with sharp diamond indenters. These common methods as described for example in EN 1071-3 often fail for the combination of hard coatings on soft substrates due to very small critical loads or no detectable failure modes at all. Hence in the industry a lot of highly subjective and provisional test methods are used. On the one hand, quantitative comparability is difficult with common methods since defects already occur at very small loads for ductile and relative soft substrate materials like plastics. On the other hand, wear of the indenter in contact with hard coatings like pure diamond coatings requires its cost-intensive replacement.In this article a macroscopic tribological-mechanical test method is suggested which uses balls of hardened steel as indenters. A wide scope can be applied for both soft and hard coatings and different substrate materials. By variation of the ball-diameter, the normal contact force and the sliding speed different levels of stress and wear can be induced to analyze the tribological and mechanical behavior between body and counterpart as well as the interface of coating and substrate. To determine scratch resistance close to reality as usual scratch conditions on consumer products are better represented by a small ball than a sharp diamond indenter. Another benefit of the presented test method is the cost saving acquisition of the balls for indentation in very high quality as they are standard parts in the ball bearing industry. For every test on very hard coatings a new ball can be used with the possibility to detect the wear both on the base object and the counterpart. The occurring failure modes of coating and substrate also can be compared with comparatively easy numerical models to verify the results. Additionally to the test concept, first results of different coatings will be presented in this paper and compared with the results of common scratch tests.
UnivIS-Import:2015-03-09:Pub.2011.tech.FT.FT-KLMEFK.amodif_0
Keywords: Adhesion; Characterization; Critical load; Scratch resistance; Scratch test; Soft substrates

Amorphe Kohlenstoffschichten für die Blechmassivumformung - Wartzack, Sandro; Hetzner, Harald; Tremmel, Stephan (Zeitschrift für wirtschaftlichen Fabrikbetrieb, 2012)
UnivIS-Import:2015-03-09:Pub.2012.tech.FT.FT-KLMEFK.amorph_6

Amorphe Kohlenstoffschichten für Werkzeuge der Blechmassivumformung - Weikert, Tim; Tremmel, Stephan (Aktuelle Entwicklungen im Bereich der Umformtechnik, 2020)
Keywords: Tribologie; amorphe Kohlenstoffschichten; lokal angepasste Reibungszustände; Verschleiß

Amorphous Carbon Coatings for Locally Adjusted Tribological Properties in Sheet Bulk Metal Forming - Hetzner, Harald; Tremmel, Stephan; Wartzack, Sandro (Key Engineering Materials, 2012)
In sheet bulk metal forming, locally adapted friction properties of the contact tool/workpiece are an appropriate means for the targeted enhancement of the material flow, enabling an improved form filling and lowered forming forces. However, the implementation of desirable friction conditions is not trivial. And further, friction is inseparably linked to wear and damage of the contacting surfaces. This calls for a methodological approach in order to consider tribology as a whole already in the early phases of process layout, so that tribological measures which allow fulfilling the requirements concerning local friction and wear properties of the tool surfaces, can already be selected during the conceptual design of the forming tools. Thin tribological coatings are an effective way of improving the friction and wear properties of functional surfaces. Metalmodified amorphous carbon coatings, which are still rather new to the field of metal forming, allow tackling friction and wear simultaneously. Unlike many other types of amorphous carbon, they have the mechanical toughness to be used in sheet bulk metal forming, and at the same time their friction properties can be varied over wide ranges by proper choice of the deposition parameters. Based on concrete research results, the mechanical, structural and special tribological properties of tungstenmodified hydrogenated amorphous carbon coatings (a-C:H:W) are presented and discussed against the background of the tribological requirements of a typical sheet bulk metal forming process.© (2012) Trans Tech Publications.
UnivIS-Import:2015-03-09:Pub.2012.tech.FT.FT-KLMEFK.amorph
Keywords: a-C:H:W; Amorphous carbon coatings; DLC; Forming tool tribology; Sheet bulk metal forming

Amorphous Carbon Coatings for Sheet-Bulk Metal Forming Tools - Weikert, Tim; Tremmel, Stephan (Sheet Bulk Metal Forming. Research Results of the TCRC73, 2020)
Sheet-bulk metal forming processes are commonly characterized by temporally and locally varying stress conditions, likely to affect material flow during forming and therefore the geometrical accuracy of formed parts. Local modifications of friction conditions can contribute to control the flow of material and simultaneously to reduce process forces and tool wear. This chapter discusses the systematical development and evaluation of amorphous carbon coatings aiming to adapt tribological conditions and to increase wear resistance of coated forming tools. Considering requirements and boundary conditions of forming processes, especially tungsten-modified amorphous carbon coatings demonstrated their beneficial tribological-mechanical behavior in high loaded sliding contacts due to low adhesion to steel. Coating development based on design of experiments revealed wide ranges of adjustable frictional behavior and mechanical properties contributing to local tribological conditions by the application of masking techniques. The coatings proved their operational performance in application-oriented forming processes, ranging from friction tests to simulated and experimental forming operations. Multilayer strategies increased the coatings’ toughness and their resistance to wear and fatigue. These benefits, along with an additional experimentally verified sensory function for wear condition monitoring, may provide an individual and improved service life of amorphous carbon coated forming tool

Amorphous carbon coatings for total knee arthroplasty – a knee simulator evaluation - Neusser, Kevin; Marian, Max; Bartz, Marcel; Wartzack, Sandro; Rothammer, Benedict (6th YOUNG TRIBOLOGICAL RESEARCHER SYMPOSIUM, 2023)
The purpose of endoprosthetic joint replacement is to regain the functionality and allow patients to live a more mobile and pain-free life. Aseptic loosening of total knee arthroplasty (TKA) is a major cause of premature failure, with wear particles removed from the implant materials being largely responsible. Therefore, great efforts are being made to reduce the wear of polymer inlays by surface modifications. This study concentrates on the evaluation of the effectiveness of wear-reducing amorphous carbon coating systems on hard-on-soft pairings (metal-on-polymer). The biotribological behavior of the uncoated and coated TKA is investigated in a knee simulator according to ISO 14243. The articulation is lubricated with diluted bovine calf serum (BCS) at 37 °C mimicking in vivo boundary conditions and motion parameters. The wear is quantified by gravimetry after a total of 3.5 million cycles and the gravimetric wear of the polymeric tibial inlays are calculated in intervals of 500,000 cycles. This testing reveals the applicability of amorphous carbon (also known as diamond-like carbon (DLC)) coatings to the considered materials used for biomedical applications. The results represent an important milestone in demonstrating the potential of DLC coated contact partners for wear reduction in human joints, thus enabling more focused research and understanding in the development of biotribologically effective coating system

Amorphous carbon coatings for total knee arthroplasty – A knee simulator evaluation - Neusser, Kevin; Marian, Max; Bartz, Marcel; Wartzack, Sandro; Rothammer, Benedict (64. Tribologie-Fachtagung. Reibung, Schmierung und Verschleiß. Forschung und praktische Anwendungen., 2023)
The purpose of endoprosthetic joint replacement is to regain the functionality and allow patients to live a more mobile and pain-free life. Aseptic loosening of total knee arthroplasty (TKA) is a major cause of premature failure, with wear particles removed from the implant materials being largely responsible. Therefore, great efforts are being made to reduce the wear of polymer inlays by surface modifications. This study concentrates on the evaluation of the effectiveness of wear-reducing amorphous carbon coating systems on hard-on-soft pairings (metal-on-polymer). The biotribological behavior of the uncoated and coated TKA is investigated in a knee simulator according to ISO 14243. The articulation is lubricated with diluted bovine calf serum (BCS) at 37 °C mimicking in vivo boundary conditions and motion parameters. The wear is quantified by gravimetry after a total of 3.5 million cycles and the gravimetric wear of the polymeric tibial inlays are calculated in intervals of 500,000 cycles. This testing reveals the applicability of amorphous carbon (also known as diamond-like carbon (DLC)) coatings to the considered materials used for biomedical applications. The results represent an important milestone in demonstrating the potential of DLC coated contact partners for wear reduction in human joints, thus enabling more focused research and understanding in the development of biotribologically effective coating systems. <

Amorphous Carbon Coatings for Total Knee Arthroplasty – a Knee Simulator Evaluation - Rothammer, Benedict; Neusser, Kevin; Bartz, Marcel; Wartzack, Sandro (24, 2024)

Amorphous Carbon Coatings for Total Knee Replacements—Part I: Deposition, Cytocompatibility, Chemical and Mechanical Properties - Rothammer, Benedict; Neusser, Kevin; Marian, Max; Bartz, Marcel; Krauß, Sebastian; Böhm, Thomas; Thiele, Simon; Merle, Benoit; Detsch, Rainer; Wartzack, Sandro (Polymers, 2021)
Diamond-like carbon (DLC) coatings have the potential to reduce implant wear and thus to contribute to avoiding premature failure and to increasing service life of total knee replacements (TKAs). This two-part study addresses the development of such coatings for ultrahigh molecular weight polyethylene (UHMWPE) tibial inlays as well as cobalt-chromium-molybdenum (CoCr) and titanium (Ti64) alloy femoral components. While a detailed characterization of the tribological behavior is the subject of part II, part I focusses on the deposition of pure (a-C:H) and tungsten-doped hydrogen-containing amorphous carbon coatings (a-C:H:W) and the detailed characterization of their chemical, cytological, mechanical and adhesion behavior. The coatings are fabricated by physical vapor deposition (PVD) and display typical DLC morphology and composition – as verified by focused ion beam scanning electron microscopy and Raman spectroscopy. Their roughness is higher than that of the plain substrates. Initial screening with contact angle and surface tension as well as in vitro testing by indirect and direct application indicate favorable cytocompatibility. The DLC coatings feature 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 sufficient for the use in TKAs.<br
Keywords: DLC coating; Biomedical applications; Biotribology; UHMWPE; CoCr; Ti64; Total knee arthroplasty; Cytocompatibility; Hardness; Adhesion

Amorphous Carbon Coatings for Total Knee Replacements—Part II: Tribological Behavior - Rothammer, Benedict; Marian, Max; Neusser, Kevin; Bartz, Marcel; Böhm, Thomas; Krauß, Sebastian; Schroeder, Stefan; Uhler, Maximilian; Thiele, Simon; Merle, Benoit; Kretzer, J. Philippe; Wartzack, Sandro (Polymers, 2021)
Diamond-like carbon coatings may decrease implant wear, therefore, they are helping to reduce aseptic loosening and increase service life of total knee arthroplasties (TKAs). This two-part study addresses the development of such coatings for ultrahigh molecular weight polyethylene (UHMWPE) tibial inlays as well as cobalt-chromium-molybdenum (CoCr) and titanium (Ti64) alloy femoral components. While the deposition of a pure (a-C:H) and tungsten-doped hydrogen-containing amorphous carbon coating (a-C:H:W) as well as the detailed characterization of mechanical and adhesion properties were the subject of Part I, the tribological behavior is studied in Part II. Pin-on-disk tests are performed under artificial synovial fluid lubrication. Numerical elastohydrodynamic lubrication modeling is used to show the representability of contact conditions for TKAs and to assess the influence of coatings on lubrication conditions. The wear behavior is characterized by means of light and laser scanning microscopy, Raman spectroscopy, scanning electron microscopy and particle analyses. Although the coating leads to an increase in friction due to the considerably higher roughness, especially the UHMWPE wear is significantly reduced up to a factor of 49% (CoCr) and 77% (Ti64). Thereby, the coating shows continuous wear and no sudden failure or spallation of larger wear particles. This demonstrated the great potential of amorphous carbon coatings for knee replacements.
Keywords: DLC coating; Biomedical applications; Biotribology; UHMWPE; CoCr; Ti64; Total knee arthroplasty; Pin-on-disk; Friction; Wear

A Musculoskeletal Human Model-Based Approach for Evaluating Support Concepts of Exoskeletons for Selected Use Cases - Molz, Carla; Yao, Zhejun; Sänger, Johannes; Gwosch, Thomas; Weidner, Robert; Matthiesen, Sven; Wartzack, Sandro; Miehling, Jörg (Proceedings of the Design Society, 2022)
This paper presents an approach for evaluating exoskeleton support concepts through biomechanical analyses on a musculoskeletal human model. By simplifying the support forces of an exoskeleton as external forces, different support concepts can be biomechanically evaluated for the respective use case without concrete design specifications of the exoskeleton. This enables an estimation of the resulting relief and strain on the human body in the early stages of exoskeleton development. To present the approach, the use case of working at and above head height with a power tool is chosen.
Keywords: user-centred design; design optimisation; supportive technologies; musculoskeletal human model; exoskeleton

An adapted Method for Design Process Capturing to meet the challenges of digital product development - Gerschütz, Benjamin; Spießl, Bettina Vanessa Martina; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the International Conference on Engineering Design (ICED21), 2021)
n our modern, interconnected and globalized world, design is in motion, to adapt to new situations. But successful Design in Motion must be based on Processes in Motion. For a target-oriented adaptation of the processes to the new, challenging conditions, the as-is procedures must be captured and analysed. For this analysis, established capturing procedures from production or administration cannot be used due to some special features of design processes and workflows, which will be discussed in this contribution. To compensate for the weaknesses of existing methods, we propose an adapted method for holistic design process capturing. With the procedure, we want to enable an economic process analysis, which is crucial for small and medium-size companies in particular. To give an insight into the practical application of the method, we exemplarily analyse the process of a shaft construction and FEM-evaluation by two different employees. Based on this analysis and to verify the relevance of the presented approach, an evaluation with respect to the requirements is done. In our modern, interconnected and globalized world, design is in motion, to adapt to new situations. But successful Design in Motion must be based on Processes in Motion. For a target-oriented adaptation of the processes to the new, challenging conditions, the as-is procedures must be captured and analysed. For this analysis, established capturing procedures from production or administration cannot be used due to some special features of design processes and workflows, which will be discussed in this contribution. To compensate for the weaknesses of existing methods, we propose an adapted method for holistic design process capturing. With the procedure, we want to enable an economic process analysis, which is crucial for small and medium-size companies in particular. To give an insight into the practical application of the method, we exemplarily analyse the process of a shaft construction and FEM-evaluation by two different employees. Based on this analysis and to verify the relevance of the presented approach, an evaluation with respect to the requirements is don
Keywords: Process modelling; Organisation of product development; Digital/Digitised engineering value chanins

An advanced procedure model for property-based product development - Luft, Thomas; Krehmer, Hartmut; Wartzack, Sandro (DS 75-8: Proceedings of the 19th International Conference on Engineering Design (ICED13), 2013)
Increasing functionality, increasing individualization as well as the enormous complexity of modern products lead to steadily increasing challenges in the domain of product development. This causes a necessity of a novel approach for a purposeful guidance to lead developers through the process of product development. Therefore the objective of this work is to present an advanced procedure model for property-based product development which is showing effects of characteristics specifications based on a structured mapping of product properties. Due to its structure and the integration of a multitude of individual approaches that are developed within this paper, the presented procedure model provides product developers with a detailed guidance to the process of product development. Moreover, developers are supported not only in the field of preventative avoidance of unnecessary design iterations but also in in dealing with unavoidable iterations. By continuously monitoring the productâs degree of maturity information about the achievement of the required properties and about necessary changes can be deduced.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.anadva
Keywords: Design methodology; property-property-based product development; design process; process modeling; design management

Analyse anlagenspezifischer Fertigungseinflüsse auf die Genauigkeit FDM-gedruckter Bauteile - Hallmann, Martin; Kunz, David; Schleich, Benjamin; Wartzack, Sandro (Design for X. Beiträge zum 29. DfX-Symposium, 2018)
Since the first successful integrations of additive manufacturing processes into industrial production, the achievable component qualities, such as geometric accuracy and surface quality, have improved significantly. Hence, such processes are often used for the manufacturing of directly usable components. Nevertheless, the deviations caused by the generative production principles are inevitably and strongly dependent on the respective machine. To address these aspects in the tolerance-driven design of additively manufactured components, a procedure for the acquisition of machine-specific component deviations is presented and applied to a revolute joint as an exampl
Keywords: Fused Deposition Modeling; Geometric Accuracy; Influences of production; Design of Experiment

Analyse der Betriebseigenschaften von losen Schmierringen und Ableitung von Gestaltungs- und Auslegungsrichtlinien - Müller, Matthias; Tremmel, Stephan; Weschta, Martin; Stangl, Thomas; Wartzack, Sandro (Wälzlagerkolloquium, 2015)

Analyse und Bewertung von Bohrdaten beim hydraulischen Hammerbohren im Projekt Geostar - Bartz, Marcel; Wittig, Volker; Maeggi, Kurt (Conference Proceedings: Der Geothermiekongress 2013, 2013)

Analysing the Tribological Behaviour of DLC-Coated Dry-Running Deep Groove Ball Bearings with Regard to the Ball Material - Kröner, Julia; Kursawe, Serge; Musayev, Yashar; Tremmel, Stephan (Applied Mechanics and Materials, 2016)
In many applications conventional lubricants which are based on mineral oils cannot be used because it is physically impossible or forbidden by regulations. Operating machine elements, such as rolling element bearings, under dry running conditions is highly demanding in regard to the materials that are being used. Applying thin films to steel substrates was identified as an approach to achieve wear resistant and low friction surfaces at reasonable cost. Furthermore, a substitution of mineral oil based lubricants by coatings is an achievement in terms of sustainability, environmental friendliness and conserving resource
Keywords: Ceramics Balls; Conserving Resources; Deep Groove Ball Bearings; DLC Coatings; Dry-Running; Friction Reduction; Steel Balls

Analysis and optimization-based synthesis of compliant mechanisms - Hasse, Alexander; Campanile, Lucio Flavio (Advances in Science and Technology (Volume 58), 2008)
Compliant mechanisms fulfil a desired force and displacement characteristic. The development of such structures having a defined kinematical motion and subjected to several constraints, like deformability, stiffness and activation force is highly challenging. The present work deals with a methodology for analysing compliant mechanisms considering geometrically nonlinear deformations. By assembling pre-calculated nonlinear beam elements a new beam truss approach is introduced. The accuracy and quality of the mechanical model are verified by selected examples and compared to existing methods. © 2008 Trans Tech Publications, Switzerlan
Keywords: Beam truss; Compliant mechanisms; Deformability; Displacement characteristics; Existing methods; Geometrically nonlinear; Large deflection; Mechanical models; Non-linear beams; Selected examples

Analysis of hybrid structures: easy and efficient - Witzgall, Christian; Kellermeyer, Markus; Wartzack, Sandro (Adhesion Adhesives & Sealants, 2016)

Analysis of the effects of manufacturing-caused deviations and varying operation parameters on operation-depending deviations of systems in motion - Walter, Michael; Wartzack, Sandro (Proceedings of the 12th CIRP Conference on Computer Aided Tolerancing, 2012)
UnivIS-Import:2015-04-16:Pub.2012.tech.FT.FT-KLMEFK.analys

Analysis of tool-sided surface modifications for dry deep drawing of deep drawing steel and aluminum alloys in a model process - Steiner, Jennifer; Häfner, Tom; Zhao, Rong; Andreas, Kolja; Schmidt, Michael; Tremmel, Stephan; Merklein, Marion (Dry Metal Forming Open Access Journal, 2017)
The concept of sustainability motivates the development of energy-saving and low-polluting production processes. A sheet metal forming process without usage of lubricants is considered as one of these green production technologies. Forming processes without the need for traditional lubricants save process steps and additional costs to remove the remaining lubrication from the workpiece after forming. In order to realize such a dry forming process and to adjust the material flow effectively, tool surfaces were modified by amorphous carbon coatings and different surface finishing processes for roughness adjustment. To verify the general feasibility of the lubricant-free metal forming process, deep drawing of rectangular cups with and without lubrication with conventional forming tools was investigated. The dry deep drawing process was modelled numerically to analyze process parameters and identify critical contact conditions. By strip drawing tests, the tribological behavior of ta-C and a-C:H coated tools with different surface treatments was investigated. The deposition process and resulting properties of a-C:H coatings were further analyzed to improve their tribological performance. The effects of the process parameters – deposition temperature and bias voltage in the deposition chamber – were investigated using the one-factor-at-a-time method. The strip drawing tests revealed a high influence of the surface roughness of coated tools on the tribological behavior. Therefore, laser based smoothing was further investigated in this study. Laser radiation at 355 nm wavelength was applied as an effective and minimum heat-generating technique to remove the roughness asperities on ta-C coatings which are built during its growth. Finally, ta-C and a-C:H coatings were applied on tool surfaces and tested in a drawing process of strip profiles. As reference the same forming process with a conventional forming tool was carried out.<br
Keywords: Dry Deep Drawing; Tribology; Carbon Based Coatings; Laser Based Modification

Analysis of tribological behavior of surface modifications for a dry deep drawing process - Henneberg, Johannes; Rothammer, Benedict; Zhao, Rong; Vorndran, Martin; Tenner, Jennifer; Krachenfels, Kim; Häfner, Tom; Tremmel, Stephan; Schmidt, Michael; Merklein, Marion (Dry Metal Forming Open Access Journal, 2019)
The global trend towards more environment-friendly and sustainable production motivates the development of efficient manufacturing processes. Forming technology has great potential regarding that due to its high material efficiency. Research is necessary to improve the sustainability of established forming processes such as deep drawing. One possibility to improve the environmental friendliness of deep drawing is the realization of lubricant-free processes. This avoids the usage of harmful lubricants. Additionally, it has the potential to shorten process chains by eliminating cleaning steps. However, dry deep drawing is associated with challenges. Due to the lack of a lubricant between tool and workpiece, friction and wear increase. An approach to overcome these challenges is the usage of modified tool surfaces. In this context, the aim of this research is to investigate dry deep drawing operations under application-oriented conditions. Firstly, the cause-effect relationships between the properties and tribological performance for a-C:H and ta-C coating systems as well as laserbased micro-textures are investigated in strip drawing tests using the workpiece materials DC04 and AA5182. Therefore, different amorphous carbon coating approaches for DC04 and AA5182 are evaluated. Beside of coatings, diverse laser micro-texturings are investigated and applied on forming tools. Key parameters are identified, which result in low friction and adhesion. Based on these findings, the different modifications are evaluated. Promising modifications are selected and applied in a novel test rig under application-oriented conditions to analyze their durability. The test rig enables the time- and material-efficient forming of a great number of parts. In this regard, in addition to the occurring process forces, the tool and component topographies are determined at periodic intervals in order to derive the cause-effect relationships between friction, wear and component quality as well as to demonstrate the feasibility of dry deep drawing operations under application-oriented forming conditions.<br
Keywords: Dry Deep Drawing; Tribology; Carbon Based Coatings; Laser Based Modification

Analyzing the degradation of pre-damaged PV-modules - Buerhop, Claudia; Winkler, Thilo; Wirsching, Sven; Pickel, Tobias; Bemm, Andreas; Camus, Christian; Hauch, Jens; Brabec, Christoph (Proc. SPIE 10370, Reliability of Photovoltaic Cells, Modules, Components, and Systems X, 2017)
Cracked PV-modules are frequently detected in PV-systems. The impact of cracked cells on the energy yield and module performance under real operating conditions is not yet understood but of great relevance. Standard tests cannot reveal the relevant information conclusively. Therefore, we conducted a twofold analysis. 1) field exposure (global analysis on string level as well as detailed analysis on module level), and 2) load testing in the lab. Here, we present comparative electroluminescence (EL-) images recorded in an outdoor test stand and during load testing. Additionally, infrared (IR-) images as well as power data obtained from loaded and operating (field) conditions are discusse
Keywords: pre-cracked modules; field tests; loading tests; power measurements; IR-imaging; performance loss

Analyzing the effect of prestressing forces on selective compliant mechanisms: A case study - Mauser, Kristian; Friese, Jan; Hasse, Alexander (Proceedings of the ASME Design Engineering Technical Conference, 2019)
Once it is designed, the stiffness of a compliant mechanism is not intended to be changed in order to adapt to special operation conditions. Nevertheless, various operation tasks e.g. mechanical grippers, would benefit from such a feature. The effect of axial compression forces, however, is well known to reduce the transverse stiffness of beam-like structures. This paper deals with the effect of prestressing forces on compliant mechanisms. For this purpose, a mathematical description for a modal analysis of compliant mechanisms – based on the author’s former publications – is presented first. Building on this and using a compliant mechanism with one desired translational motion as example, the effect of prestressing forces on the desired deformation and its related stiffness value is analyzed using conventional methods which are based on the Bernoulli-Euler beam equation. However, these methods do not usually consider the undesirable deformations of a mechanism. The modal analysis mentioned above is therefore used in order to examine the effect of prestressing forces on both the desired and undesired deformations. In this analysis, two different compliant mechanisms in several load cases are examined.
CRIS-Team Scopus Importer:2019-12-24
Keywords: Compliant Mechanisms; Prestressing Forces; Selective Compliance; Variable Stiffness

An analytical exact, locking free element formulation for thin-walled composite Timoshenko beams - Jäger, Michael; Albertsen, Jacqueline; Wartzack, Sandro (Computer Methods in Applied Mechanics and Engineering, 2025)
Spatial truss structures represent a robust, cost-effective, and efficient lightweight design, especially when isotropic materials are substituted with lightweight materials such as composites. During early design phases, truss structures are often subject to optimisations. In order to achieve this in an efficient manner, it is essential to employ a precise yet cost-effective computational model. The most common methodology for the analysis of spatial truss structures employs hinged joints in conjunction with struts that are only subject to tension or compression. However, this approach does not account for the bending and coupling effects inherent to struts manufactured from composite materials. In particular, when employing asymmetric laminates, these effects can no longer be ignored. In order to incorporate these effects, it is common practice to use Finite Element Analysis tools. Particularly for large spatial truss structures comprising struts with slender and thin-walled cross-sections, a large number of solid or shell elements is required, which results in time-consuming simulations. This contribution presents a fully analytical thin-walled composite beam element, applicable to an arbitrarily shaped, closed cross-section. The beam model incorporates two distinct composite material models, namely the Classical Laminate Plate Theory and the First Order Shear Deformation Theory. Moreover, it is capable of simulating asymmetric laminates and modelling the coupling effects within these laminates. Utilising the exact third-order solution of a composite Timoshenko-Ehrenfest beam enables the locking-free representation of an individual strut with a single beam element. In comparison to the conventional shell / solid Finite Element Analysis, this approach results in a substantial reduction in the number of degrees of freedom, by a factor of several orders of magnitude. As a result, the required computational time is significantly reduced. In the case of a single strut, the computational time is reduced by a factor between 160 and 430. For an exemplary truss structure comprising 64 struts, a reduction in computational time of approximately 100 000 times is reached. The numerical comparisons presented in this contribution demonstrate that the model is highly accurate, particularly for tubular and elliptical cross-sections including symmetric and asymmetric laminate
Keywords: Lightweight design; Spatial truss structures; Structural optimisation; Thin-walled composite beams; Timoshenko beam

An Approach for Cross-Domain Optimization for Automated Adaptation Design of Mechatronic Systems - Behringer, Marc; Götz, Stefan; Wartzack, Sandro (DS 133: Proceedings of the 35th Symposium Design for X (DFX2024), 2024)
The product development of mechatronic systems remains complicated as interdisciplinary system interrelations and divergent requirements from the involved engineering domains must be taken into account. Thus, the inherent complexity and interdependencies of mechatronic systems usually require an iterative procedure to generate an optimized product even for small design adaptations. Therefore, the proposed approach aims to automate subprocesses in the adaptation design of mechatronic systems from the problem identification to the optimized product. It involves a cross-domain optimization by utilizing the knowledge from previous product development cycles and optimization histories. The approach is demonstrated using an electronic window regulator as an exampl
Keywords: Adaptation Design; Mechatronic Systems; Knowledge-Based Engineering; Optimization; Systems Engineering

An approach for determining the influence of manufacturing process parameters on product quality characteristics - Heling, Björn; Schleich, Benjamin; Wartzack, Sandro (Procedia CIRP, 2020)
Scattering manufacturing process parameters affect the quality of manufactured products, because the product properties deviate from the nominal design. If the desired quality requirements are not met, individual part tolerances can be adjusted in such a way that the required reject rates are achieved. In this context, different methods can be used to determine the individual contributors and to quantify the influence of the individual part tolerances on the quality of the manufactured product. In all existing approaches, however, only geometric tolerances are considered but not the varying manufacturing process parameters that are responsible for the geometrical part deviations. To overcome this, in this article, a novel approach is presented that allows determining the influence of manufacturing process parameters on quality characteristics for systems in motion. The novel approach is also highlighted in a case study of an X-ray shutter. <br
Keywords: Tolerance Synthesis; Interdisciplinary process-oriented Tolerance Management; Sensitivity Analysis

An approach for semi-automatic redesign of mechatronic products by multidisciplinary optimisation - Walter, Leonie; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the Design Society: International Conference on Engineering Design, 2021)
Mechatronic products are widely spread today, but their development still is a challenge. In addition, with the trend of individualisation, not only one solution must be designed but multiple configurations are needed to fulfil customer-specific requirements. To reduce cost and development time, usually existing products are adapted for this purpose. Even though a lot of knowledge is already available through the previous product version, because of multiple disciplines that must be considered in mechatronic systems, even redesign processes are complex. To support the adaption of mechatronic products to changed requirements, an approach to systematically reuse the knowledge available from previous product versions is proposed in this contribution. Through multidisciplinary behaviour optimisation, the solution space is reduced to build an adapted product meeting the new requirements. The approach is explained in detail and illustrated with the example of an electric window regulator and the results are discussed thoroughl
Keywords: Mechatronics; Optimisation; Product modelling / models; Redesign

An Approach of a Knowledge-based Process to Integrate Real Geometry Models in Product Simulations - Katona, Sebastian; Koch, Michael; Wartzack, Sandro (Procedia CIRP, 2016)
Simulation driven product development is state of the art to insure that the desired characteristics in use behave as requested without performing a time-consuming testing using expensive prototypes. To achieve the aim of realistic and confidential results within this product simulations, a tremendous afford (i.e. when taking different non-linearities into account, like material behavior, contact situations, large deflections etc.) is necessary. Conflicting to this, the ideal CAD-model is always used for the analysis, despite knowing the effect, that every manufactured component shows differences to its ideal geometry. Within this paper an approach of a knowledge-based process to integrate real geometry data into product simulations is given. Furthermore, different methods for preparation of the simulation models are represented.
Keywords: Computer aided design (CAD); deformation; finite element method (FEM); geometry; knowledge-based system; process; simulation; strucural analysis

An Approach to the Sensitivity Analysis in Variation Simulations considering Form Deviations - Schleich, Benjamin; Wartzack, Sandro (Procedia CIRP, Volume 75, 2018)
In tolerance and variation simulations, sensitivity analyses are used to assess the influences of tolerance specifications and geometrical deviations on the assembly key characteristics and to support product and process developers in deriving more suitable tolerancing decisions and in optimizing manufacturing and assembly processes. However, established methods to the sensitivity analysis in the context of variation simulations disregard important statistical dependencies, which occur when considering form deviations. To overcome these shortcomings, an approach to the density-based sensitivity analysis in variation simulations considering form deviations based on Skin Model Shapes is presented. The method is highlighted and discussed employing a typical tolerance analysis case stud
Keywords: Sensitivity Analysis; Tolerance Analysis; Skin Model Shapes

An Approach to Transfer Biological Solutions Based on the Interaction of Mechanisms to Technical Products - Bartz, Marcel; Uttich, E.; Wanieck, K.; Bender, B.; Wartzack, Sandro (Proceedings of the Design Society, 2022)
Biological solutions are often used for developing technically innovative products in a biomimetic process. However, biological solutions do not always make it into a successful technical product, e.g. due to a lack of knowledge on the mechanisms of action. A new approach is presented for transferring biological solutions based on complex mechanisms of action. It is based on mathematical optimization methods and applied to the lightweight design of the musculoskeletal system. Finally, first technical implementations in the field of robotics, among others, will be presented.
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Keywords: biologically inspired design; biomimicry (biomimetics); lightweight design; topological optimisation

An efficient bionic topology optimization method for transversely isotropic materials - Völkl, Harald; Klein, Daniel; Franz, Michael; Wartzack, Sandro (Composite Structures, 2018)
Optimization specifically for fiber reinforced plastics (FRP) is becoming more and more important for creating high-quality composite structures. Yet, in spite of the increasing use of topology optimization (TO) within product development, specific TO methods for transversely isotropic materials like FRP are scarce in research and even more scarce in practical application. This is amongst other reasons caused by the challenge of simultaneous optimization of mutually dependent material distribution and fiber orientations, which poses an obstacle to established gradient-based optimization routines in terms of iterations (run time) and gradient formulation. Thus, based on bionic methods, an efficient, empirical optimization method is proposed to enable fast and FRP-suitable geometry propositions. Case studies show efficiency and effectiveness: the new approach offers very fast convergence; plus perceptible stiffness gains compared to established topology optimization for isotropic material
Keywords: Structural optimization Fiber-reinforced plastics Finite element analysis Bionics

An Empirical Investigation of the Impact of an Axially Oscillating Shaft on Friction and Lubrication in Cylindrical Roller Bearings - Meinel, Andreas; Tremmel, Stephan (Bearing World Journal, 2019)
Rolling element bearings experience dynamic axial thrust and oscillating shaft movements of various frequencies and amplitudes in a multitude of applications, especially in heavy-duty machinery. These operating conditions can cause significant friction losses which entails higher operating temperatures and lower lubricant operating viscosities. Dynamic axial shaft movements increase shearing between rollers and raceways excessively which impairs the mechanical stability of the lubricant. In consequence, this results in accelerated lubricant degradation and may cause insufficient lubrication or even premature bearing failure. In order to choose a suitable lubricant for such a bearing application that experiences axial shaft movements or to be able to adequately schedule lubricant maintenance intervals, the occurring shear- or friction forces between rollers and raceways due to the axial oscillations are of particular interest. Therefore, in an experimental study, an oil-lubricated cylindrical roller bearing NU210 has been subjected to dynamic axial shaft movements of various frequencies and amplitudes. Two specifically designed bearing test rigs are introduced within the scope of this paper and the experimental procedure is presented. The results obtained which include measurements of axial friction forces between rollers and raceways, steady-state operating temperatures, bearing friction losses as well as cage slippage are discussed in detail and an axial friction coefficient is derived from the results. Concluding, a short assessment is given, to what extend axial shaft movements might exhibit a critical impact on lubricant performance, friction and wea
Keywords: cylindrical roller bearings; oscillations; bearing friction; lubrication

A neurorobotic platform for locomotor prosthetic development in rats and mice - von Zitzewitz, Joachim; Asboth, Leonie; Fumeaux, Nicolas; Hasse, Alexander; Baud, Laetitia; Vallery, Heike; Courtine, Grégoire (Journal of Neural Engineering, 2016)
Objectives. We aimed to develop a robotic interface capable of providing finely-tuned, multidirectional trunk assistance adjusted in real-time during unconstrained locomotion in rats and mice. Approach. We interfaced a large-scale robotic structure actuated in four degrees of freedom to exchangeable attachment modules exhibiting selective compliance along distinct directions. This combination allowed high-precision force and torque control in multiple directions over a large workspace. We next designed a neurorobotic platform wherein real-time kinematics and physiological signals directly adjust robotic actuation and prosthetic actions. We tested the performance of this platform in both rats and mice with spinal cord injury. Main Results. Kinematic analyses showed that the robotic interface did not impede locomotor movements of lightweight mice that walked freely along paths with changing directions and height profiles. Personalized trunk assistance instantly enabled coordinated locomotion in mice and rats with severe hindlimb motor deficits. Closed-loop control of robotic actuation based on ongoing movement features enabled real-time control of electromyographic activity in antigravity muscles during locomotion. Significance. This neurorobotic platform will support the study of the mechanisms underlying the therapeutic effects of locomotor prosthetics and rehabilitation using high-resolution genetic tools in rodent models.
Keywords: robotics; spinal cord injury; neuroprosthetics; locomotion; balance

A new approach to first tolerance evaluations in the conceptual design stage based on tolerance graphs - Götz, Stefan; Schleich, Benjamin; Wartzack, Sandro (Procedia CIRP, Volume 75, 2018)
Tolerancing is commonly performed in late design stages, in which the product geometry is fully defined. However, this often leads to high manufacturing costs or expensive design changes. Therefore, motivated by the idea of frontloading, a new approach for first tolerance evaluations in conceptual design stages is developed, which enables a first tolerance specification and analysis based on the few geometry data available. Together with semantic information of the interface notations of adjacent parts, graphs including relevant geometry elements and tolerance information are generated. These graphs support designers with a first assessment of tolerance situations before the geometry is finally defined.<br
Keywords: Robust Design; Tolerance Graph; Early Design Stage

A New Design Method for Generating Surrogate Kinematic Truss Orthoses to support Pathological Gait Patterns in Human Model Simulations - Steck, Patrick; Scherb, David; Mayer, Johannes; Jäger, Michael; Miehling, Jörg; Völkl, Harald; Wartzack, Sandro (Proceedings of the Design Society, 2023)
With increasing life expectancy, the risk of diseases of the central nervous system, such as cancer,strokes, etc., also increases. Strokes often result in injury to the sciatic nerve, which is responsible forcontrolling the calf muscles (plantar and dorsal flexors). A so-called ankle joint orthosis (AFO) helps tosupport the pathological gait and to avoid foot drop during gait. Passive orthoses are of particularimportance for research, as they do not require additional incoming energy from outside to the orthoticsystem. However, current passive orthoses are often not personalized. On the one hand, because theyusually have only a temporary muscle-building function and, on the other hand, because the individualdesign process is computationally time consuming and thus expensive. This paper presents a possibilityto pre-dimension and pre-design passive orthoses fast and cost-efficiently by reducing the complexityof the model based on volume-optimized truss elements. Therefor a traditional high calculation intensivedesign procedure is compared with the complexity reduced model to show its effectiviness and thesimilarity of the results. Witl incoming energy from outside to the orthoticsystem. However, current passive orthoses are often not personalized. On the one hand, because theyusually have only a temporary muscle-building function and, on the other hand, because the individualdesign process is computationally time consuming and thus expensive. This paper presents a possibilityto pre-dimension and pre-design passive orthoses fast and cost-efficiently by reducing the complexityof the model based on volume-optimized truss elements. Therefor a traditional high calculation intensivedesign procedure is compared with the complexity reduced model to show its effectiviness and thesimilarity of the results. <br
Keywords: Orthoses; User centred design; Lightweight design; Truss optimization; Design methods

A new design process for anatomically enhanced osteosynthesis plates - Tkany, Luisa; Hofstätter, Bernhard; Petersik, Andreas; Miehling, Jörg; Wartzack, Sandro; Sesselmann, Stefan (Journal of Orthopaedic Research, 2019)

A new "knowledge-based engineering" guideline - Luft, Thomas; Roth, Daniel; Binz, Hansgeorg; Wartzack, Sandro (DS 87-6 Proceedings of the 21st International Conference on Engineering Design (ICED17), Vol. 6: Design Information and Knowledge, 2017)
It is necessary to enable product developers to use specific engineering knowledge in an efficient and fast way during the product development process. However, existing procedures supporting the development of products are not strictly convenient to meet this challenge. This is the reason why already in the 1980 various research approaches in the area of knowledge-based engineering (KBE) have been developed. Nevertheless, there is still no uniform and universally applicable description for the industrial environment, with which a KBE application can be implemented and operated. Therefore, the aim is empowering designers to use design-related knowledge in CAD-systems as a central engineering workbench. The main research question in this paper is: How to formulate a universally applicable procedure to conduct KBE-projects with all relevant roles as well as necessary instructions and recommendations regarding specific KBE-methods and -tools? By answering this question, this contribution offers insights in general adapted definitions and perspectives, a procedure for the implementation of KBE-projects, a classification of knowledge-based engineering and a first exemplary solution.
Keywords: Computer Aided Design (CAD); Computational design methods; Design informatics; Knowledge management; Product modelling

A New Method For Passive Ankle Foot Orthosis Design – Integration Of Musculoskeletal And Finite Element Simulation - Scherb, David; Steck, Patrick; Völkl, Harald; Wartzack, Sandro; Miehling, Jörg (Proceedings of the Design Society, 2023)
Motor disorders are diseases affecting the muscle function of the human body. A frequently occurring motor disorder affects the lower leg muscles resulting in a pathological gait called foot drop. Patients have a higher risk of stumbling and falling. The most common treatment is the use of a passive ankle-foot-orthosis (AFO). However, the compensation of foot drop is only limited due to the non possible support of all rotational directions of the ankle joint. Therefore, a newly developed concept for a passive AFO is currently in work. To ensure a best possible treatment of the patient, the provided support by the AFO and required support by the patient have to be in accordance. Thus, in this contribution a method is presented that integrates model order reduced finite element analysis for computing the provided support of the AFO and musculoskeletal human models for representing the patients' gait behaviour. With the method, the design of the force generating structures of the AFO can be realized regarding the patients' requirements. The presented method is further evaluated with a specific use case. The main focus lies here in the principal functionality of the method and the provision of valid results.<br
Keywords: User centred design; Design methods; Product modelling / models; Orthosis; Musculoskeletal human model

A New Projection Based Method for the Classification of Mechanical Components Using Convolutional Neural Networks - Bickel, Sebastian; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the Design Society, 2022)
Digital engineering is increasingly established in the industrial routine. Especially the application of machine learning on geometry data is a growing research issue. Driven by this, the paper presents a new method for the classification of mechanical components, which utilizes the projection of points onto a spherical detector surfaces to transfer the geometries into matrices. These matrices are then classified using deep learning networks. Different types of projection are examined, as are several deep learning models. Finally, a benchmark dataset is used to demonstrate the competitiveness.
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Keywords: artificial intelligence (AI); data mining; data-driven design; deep learning; part classification

A New Slicer-Based Method to Generate Infill Inspired by Sandwich-Patterns for Reduced Material Consumption - Steck, Patrick; Schuler, Dominik; Witzgall, Christian; Wartzack, Sandro (Materials, 2024)
This work presents a novel infill method for additive manufacturing, specifically designed to optimize material use and enhance stiffness in fused filament fabrication (FFF) parts through a geometry-aware, corrugated design inspired by sandwich structures. Unlike standard infill patterns, which typically employ uniform, space-filling grids that often disregard load-specific requirements, this method generates a cavity inside the component to be printed and fill the space between inner and outer contours with continuous, adaptable extrusion paths. This design enables consistent support and improved load distribution, making it particularly effective for parts under bending stresses, as it enhances structural resilience without requiring additional material. Simulations performed on a 10 cm3 test part using this method showed potential reductions in material consumption by up to 77% and a decrease in print time by 78%, while maintaining stiffness comparable to parts using conventional 100% grid infill. Additionally, simulations demonstrated that the new corrugated infill pattern provides near-isotropic stiffness, addressing the anisotropic limitations often seen in traditional infill designs that are sensitive to load orientation. This geometry-aware infill strategy thus contributes to balanced stiffness across complex geometries, enhancing reliability under mechanical loads. By integrating directly with slicer software, this approach simplifies advanced stiffness optimization without the necessity of finite element analysis-based topology optimizatio
Keywords: infill pattern; additive manufacturing; lightweight design; load-corresponded design; function-integrated design; sustainable material consumption

An Experimental Study of the Effects of Dynamic Shaft Movements on Friction in Cylindrical Roller Bearings - Meinel, Andreas; Tremmel, Stephan (Bearing World, 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 and heavy-duty machinery like cranes, paper- and weaving machines, harvesters, crushers or milling plants. These operating conditions often cause significant friction losses that entail higher operating temperatures and lower lubricant operating viscosities. Dynamic axial shaft movements excessively increase shearing between rollers and raceways which impairs the mechanical stability of the lubricant. In consequence, this may result in insufficient lubrication or even premature bearing failure. In order to choose a suitable lubricant for such a bearing application that experiences axial shaft movements or to be able to adequately enhance the mechanical stability of the lubricant in this regard, the occurring shear- or friction forces between rollers and raceways are of particular interest. Therefore, in an experimental study, a cylindrical roller bearing has been subjected to dynamic axial shaft movements of various frequencies and amplitudes, utilizing a specifically designed test rig. Within the scope of this presentation, this test rig is briefly introduced and the experimental set-up is presented. The results obtained, which include measurements of axial friction forces between rollers and raceways, operating temperatures of inner and outer ring, test bearing friction moments, as well as cage slippage, are discussed in detail. Concluding, a short assessment is given, to what extend axial shaft movements might exhibit a critical impact on lubricant perfor
Keywords: cylindrical roller bearings; oscillations; bearing friction

An Experimental Study regarding Maintainability of a Rolling Bearing Arrangement Equipped with a Ring Lubricator for Oil Supply - Müller, Matthias; Tremmel, Stephan (Bearing World Journal, 2017)
Lubrication plays a decisive role in performance and operating costs of rolling bearings. Oil lubrication, which initially may be more expensive than grease lubrication, can provide longer maintenance intervals and reduce total cost of ownership, especially in case of unfavourable operating conditions. In this context, oil lubrication including a simple designed ring lubricator for oil supply, might be an economic choice for industrial operators. This paper comprises results of oil analyses obtained within a 6 000-hour long-term test featuring an oil lubricated rolling bearing arrangement equipped with a ring lubricator for oil supply. Periodically taken oil samples show changes in oil condition during the period of operation and reveal impacts on the oil caused by the ring lubricator. Crucial design criteria of a ring lubricator influencing operating characteristics of the ring and thermal behaviour of the rolling bearing are presented and evaluated regarding effects on service life of oil. Based on the data provided by the oil analyses accompanied by a final optical inspection, attainable service life of the oil is specified and compared to the relubrication interval of a grease lubricated bearing running under identical conditions. The central objectives of the presented study are to prove and quantify the benefits of using a ring lubricator in rolling bearing arrangements concerning maintainability compared to a grease lubricated rolling bearing and to identify crucial design characteristics of the ring lubricator influencing service life of the oi
Keywords: rolling element bearing; lubrication; ring lubricator; maintainability; oil analysis; oil life

Anforderungen an die Wissensakquisitionskomponente eines selbstlernenden Assistenzsystems - Röhner, Sebastian; Breitsprecher, Thilo; Wartzack, Sandro (8. Gemeinsames Kolloquium Konstruktionstechnik, 2010)
UnivIS-Import:2015-04-16:Pub.2010.tech.FT.FT-KLMEFK.anford

Anforderungen an technische Oberflächen und die Herausforderungen für den Produktentwickler - Sander, Thomas; Wartzack, Sandro (Beiträge zum 22. DfX-Symposium, 2011)
UnivIS-Import:2015-04-16:Pub.2011.tech.FT.FT-KLMEFK.anford

An indicator-based process monitoring cockpit for controlling and enhancing product development processes - an industrial case study - Luft, Thomas; Smoll, Simon; Wartzack, Sandro (Smart Product Engineering - Proceedings of the 23rd CIRP Design Conference, 2013)
The need for shorter development times, lower costs, and higher quality requires improving the performance of the product development process (PDP) continuously. Therefore the evaluation and monitoring of the product development performance is of great interest for companies wishing to increase their competitiveness. However, there are very few approaches for the performance measurement of the PDP. For this purpose, a process monitoring cockpit with the overall goal to enhance the PDP regarding time, costs, quality is presented. This approach for measuring and continuously improving the current state of a company’s PDP has been validated in an industrial case study.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.anindi
Keywords: product development process; evaluation methodology; knowledge management; decision making; continuous improvement; industrial case study

An optimized material representation for crashworthy lightweight structures within early design steps - Gruber, Georg; Wartzack, Sandro (Proceedings of the 16th International Conference on Industrial Engineering - Theory, Applications and Practice, 2011)
UnivIS-Import:2015-04-16:Pub.2011.tech.FT.FT-KLMEFK.anopti

A novel approach for the evaluation of composite suitability of lightweight structures at early design stages - Klein, Daniel; Witzgall, Christian; Wartzack, Sandro (International Design Conference - DESIGN, 2014)
UnivIS-Import:2015-04-16:Pub.2014.tech.FT.FT-KLMEFK.anovel

A novel approach to incorporating previous fatigue damage into a failure model for short-fibre reinforced plastics - Witzgall, Christian; Giolda, Jessica; Wartzack, Sandro (International Journal of Impact Engineering, 2022)
This paper describes how previous material damage due to cyclic loading can influence the failure properties of short-fibre reinforced thermoplastics under crash conditions. To enable these effects to be incorporated into numerical crash simulations, we present a mathematical failure model that takes fatigue damage into account. We perform an experimental study on the thermoplastic PBT GF30: We initially characterize the material under cyclic loading conditions. Subsequently, the behaviour of pre-damaged material specimens in highly dynamic loading experiments is compared to that of virgin specimens to determine the loss of strength due to fatigue damage. Based on the aforementioned experimental results, we develop, calibrate and implement an analytical model for use in the commercial software LS-DYNA.<br
Keywords: Short-fibre reinforced plastics; Crash simulation; Fatigue damage; Failure model

A Novel Approach to Simulating Realistic Exoskeleton Behavior in Response to Human Motion - Yao, Zhejun; Seyed Milad Mir, Latifi; Molz, Carla; Scherb, David; Löffelmann, Christopher; Sänger, Johannes; Miehling, Jörg; Wartzack, Sandro; Lindenmann, Andreas; Matthiesen, Sven; Weidner, Robert (Robotics, 2024)
Simulation models are a valuable tool for exoskeleton development, especially for system optimization and evaluation. It allows an assessment of the performance and effectiveness of exoskeletons even at an early stage of their development without physical realization. Due to the closed physical interaction between the exoskeleton and the user, accurate modeling of the human–exoskeleton interaction in defined scenarios is essential for exoskeleton simulations. This paper presents a novel approach to simulate exoskeleton motion in response to human motion and the interaction forces at the physical interfaces between the human and the exoskeleton. Our approach uses a multibody model of a shoulder exoskeleton in MATLAB R2021b and imports human motion via virtual markers from a digital human model to simulate human–exoskeleton interaction. To validate the human-motion-based approach, simulated exoskeleton motion and interaction forces are compared with experimental data from a previous lab study. The results demonstrate the feasibility of our approach to simulate human–exoskeleton interaction based on human motion. In addition, the approach is used to optimize the support profile of an exoskeleton, indicating its potential to assist exoskeleton development prior to physical prototyping.<br
Keywords: exoskeleton model; exoskeleton simulation; human–exoskeleton interaction; evaluation; optimization; human motion

A Novel Shape Retrieval Method for 3D Mechanical Components Based on Object Projection, Pre-Trained Deep Learning Models and Autoencoder - Bickel, Sebastian; Schleich, Benjamin; Wartzack, Sandro (Computer-Aided Design, 2023)
The reuse of existing design models offers great potential in saving resources and generating an efficient workflow. In order to fully benefit from these advantages, it is necessary to develop methods that are able to retrieve mechanical engineering geometry from a query input. This paper aims to address this problem by presenting a method that focuses on the needs of product development to retrieve similar components by comparing the geometrical similarity of existing parts. Therefore, a method is described, which first converts surface meshes into point clouds, rotates them, and then transforms the results into matrices. These are subsequently passed to a pre-trained Deep Learning network to extract the feature vector. A similarity between different geometries is calculated and evaluated based on this vector. The procedure employs a new type of part alignment, especially developed for mechanical engineering geometries. The method is presented in detail and several parameters affecting the accuracy of the retrieval are discussed. This is followed by a critical comparison with other shape retrieval approaches through a mechanical engineering benchmark data set.
CRIS-Team Scopus Importer:2022-10-14
Keywords: 3D object retrieval; Autoencoder; Deep Learning; Part alignment; Projection method; Shape retrieval

An Overview and Classification of Tolerance Compensation Methods - Aschenbrenner, Alexander; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the 22nd International Conference on Engineering Design (ICED19), 2019)
Technological advances as well as novel manufacturing and design paradigms, such as industry 4.0 and digitalization, offer new opportunities for innovative products. However, they also increase the product complexity and cause new challenges in the production process. Therefore, agile production approaches are crucial. Tolerance compensation provides more flexibility in the production process, as demands on dimensional accuracy of the components are reduced. As a result, tolerance compensation also offers the possibility of reducing production costs without compromising product quality. Nevertheless, tolerance compensation is often considered a reactive intervention to reduce the number of out-of-spec parts a posteriori instead of including it in the early stages of Geometrical Variations Management. The contribution tackles this issue by characterizing and categorizing different methods of tolerance compensation as well as providing design guidelines for the application of tolerance compensation methods. This enables design engineers to select a suitable tolerance compensation method for different application
Keywords: Tolerance Compensation; Robust Design; Tolerance representation and management; Uncertainty

Ansatz zur CAD-integrierten Rückführung von Konstruktionsgeometrie aus Formoptimierungsergebnissen - Stangl, Thomas; Wartzack, Sandro (Design for X. Beiträge zum 24. DfX-Symposium, 2013)
Today, the short product lifecycle is a main challenge to the product developer. This requires a high level of product maturity even in the virtual design stage. The consequence is a reduced time-to-market. Hence, the application of non-parametric shape optimization, especially the low setup-costs, robustness and high flexibility, is successfully established as a common standard. The common method for redesign of the adapted shape (triangulated surface data) in productive use is redesign by means of a CAD-system and visual interpretation. This procedure is susceptible to errors. Consequently, an efficient procedure is still lacking for seamless redesign of shape optimization results in a CAD System. This paper focuses on the development of a solution by presenting an approach and the basic structure of the associated design assistance system. By means of this application, it is possible for the product developer to integrate the complex shape changes of the optimization process in the original CAD model – even without any reverse engineering knowledge. The feature structure of the original model remains intact – and thus the intention and the knowledge of the product developer.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.ansatz
Keywords: Formoptimierung; CAD; Rückführung

Ansatz zur crashsicheren Auslegung von Leichtbaukonstruktionen unter besonderer Berücksichtigung der Fügestellen - Klein, Daniel; Wartzack, Sandro; Lindner, Christian (Design for X. Beiträge zum 23. DfX-Symposium, 2012)
UnivIS-Import:2015-04-16:Pub.2012.tech.FT.FT-KLMEFK.ansatz

Ansatz zur Ermittlung von Toleranz-Kosten-Kurven in der Serienproduktion - Brückner, Kai; Storch, Markus; Hallmann, Martin; Heling, Björn; Schleich, Benjamin; Wartzack, Sandro (Konstruktion, 2019)
Die Vergabe von Toleranzen dient der Erfüllung festgelegter Qualitätskriterien, beeinflusst jedoch zugleich wesentlich die Fertigungskosten. Um diesen Konflikt effizient zu lösen, hat sich die Methode der Toleranz-Kosten-Optimierung etabliert. Voraussetzung für eine realitätsnahe Toleranzfestlegung ist die Verfügbarkeit eines geeigneten Kostenmodells. Obgleich aus Literatur und Praxis zahlreiche Ansätze bekannt sind, eignen sich diese nur bedingt für die Serienfertigung. Um diese Lücke zu schließen, wird im Folgenden ein neuer Ansatz zur Ermittlung von Kostenkurven, welche unter anderem prozessfähigkeitsabhängige Messkosten als auch mehrere Prozessparameter berücksichtigt, vorgestellt. Das Beispiel eines Hochdruckeinspritzventils zeigt exemplarisch dessen Anwendung im industriellen Umfeld.</

Anwendung der Leichtbauprinzipien des Muskel-Skelett-Systems auf einen Gelenkarmroboter - Bartz, Marcel; Remus, Robin; Bender, Beate (Konstruktion, 2018)
Der bioinspirierte Strukturleichtbau nimmt in den letzten Jahren einen hohen Stellenwert in der Technik ein. Viele umgesetzte Prinzipien stammen dabei aus dem Muskel-Skelett-System des Menschen, wo ein Leichtbau durch das Zusammenwirken mehrerer Effekte erreicht wird, die dafür sorgen Biegebeanspruchungen zu minimieren. In diesem Artikel wird das Leichtbaupotential für die Technik am Beispiel der Auslegung eines Gelenkarmroboters untersucht. Dabei wird die klassische Auslegung durch ein bioinspiriertes iteratives Verfahren ergänzt, durch Kopplung von Mehrkörpersimulation und Strukturoptimierung. Die Vor- und Nachteile werden anhand eines Vergleichs des berechneten Konstruktionsgewichts und der dynamischen Eigenschaften eines klassisch ausgelegten Roboters diskutier

ApOL-Application Oriented Workload Model for Digital Human Models for the Development of Human-Machine Systems - Sänger, Johannes; Wirth, Lukas; Yao, Zhejun; Scherb, David; Miehling, Jörg; Wartzack, Sandro; Weidner, Robert; Lindenmann, Andreas; Matthiesen, Sven (MDPI Machines, 2023)
Since musculoskeletal disorders are one of the most common work-related diseases for assemblers and machine operators, it is crucial to find new ways to alleviate the physical load on workers. Support systems such as exoskeletons or handheld power tools are promising technology to reduce the physical load on the humans. The development of such systems requires consideration of the interactions between human and technical systems. The physical relief effect of the exoskeleton can be demonstrated in experimental studies or by simulation with the digital human model (DHM). For the digital development of these support systems, an application-oriented representation of the workload is necessary. To facilitate digital development, an application-oriented workload model (ApOL model) of an overhead working task is presented. The ApOL model determines the load (forces, torques) onto the DHM during an overhead screw-in task using a cordless screwdriver, based on experimental data. The ApOL model is verified by comparing the simulated results to the calculated values from a mathematical model, using experimental data from three participants. The comparison demonstrates successful verification, with a maximum relative mean-absolute-error (rMAE) of the relevant load components at 11.4%. The presented ApOL model can be utilized to assess the impact of cordless screwdriver design on the human workload and facilitate a strain-based design approach for support systems e.g., exoskeletons.<br
Keywords: user-centered design; digital human model; virtual sensor; exoskeleton; cordless screwdriver

A posture prediction method for ergonomic assessment of user-product interactions while grasping using musculoskeletal human models - Hartmann, Carla; Wolf, Alexander; Miehling, Jörg; Wartzack, Sandro (Proceedings of the 31st Symposium Design for X (DFX2020), 2020)
Using digital human models (DHMs) as the virtual representation of the human body enables the integration of ergonomic assessments in the product design process. Especially the use of DHMs in the early phases of product design can be decisive for competitive factors such as ergonomics or usability. Therefore, we present a method for automatic posture generation for grasping tasks using a musculoskeletal human model. This method enables ergonomic analyses without ergonomic knowledge of the product designer or subject tests. We implemented the presented method for a cylinder grasping scenario using the open source software OpenSim. Subsequently, we evaluated the implementation by means of a parameter stud
Keywords: Posture prediction; musculoskeletal simulation; digital human model

Application and validation of the matrix-based product description in a case study by using the software Loomeo - Luft, Thomas; Ewringmann, Niklas; Wartzack, Sandro (Proceedings of the 24th CIRP Design Conference 2014, Milano, Italy, 2014)
The main task of product developers is to meet the ever increasing demands on quality, cost and functionality of technical products by setting the appropriate characteristics in order to realize the product properties desired by the customer. The overall objective of the authors is to develop a suitable procedure model for property-based product development, which guides the developers purposefully through the development process. An essential part of this procedure model is the matrix-based product description, which is in the focus of this paper. The matrix-based product description is basically a so-called multi domain matrix. By using this matrix-based product description, dependencies between requirements, behaviors of the product and the product's properties and characteristics can be mapped and analyzed systematically during the product development process. Thereby, for example, the effects of characteristic changes on product properties become visible and traceable and also differential requirements are set into relationship with properties and characteristics of the product. However, it has been shown that the manual filling of the matrix-based product description is very time-consuming. Hence, a computer-aided support is indispensable. For this reason, the software Loomeo is used in this paper to investigate its potential for IT support for the matrixbased product description. The interaction of dependencies between characteristics, properties and the resulting behavior is demonstrated in this paper through the matrix-based product description using the example of a front wheel suspension of a car. Thus, the strengths and weaknesses as well as opportunities and risks of Loomeo regarding the suitability of the IT-based matrix-based product description can be determined. The findings from both the application as well as from the evaluation of the software are the basis for the improvement and extension of the matrixbased product description.
UnivIS-Import:2015-04-16:Pub.2014.tech.FT.FT-KLMEFK.applic
Keywords: case study; complexity management; design methodology; design structure matrix; Design synthesis and optimisation; Matrix-based product description; product-oriented process management

Application, evaluation and future research potential of the matrix and graph based product model - Luft, Thomas; Wartzack, Sandro (DS 84: Proceedings of the DESIGN 2016 14th International Design Conference, 2016)
The increasing individualization due to customer-specific requirements as well as the enormous complexity of modern products leads to steadily increasing challenges. To meet these challenges, the overall objective of the authors is to develop a computer aided matrix- and graphbased product modelling tool for the product-oriented process management. The aim of this paper is to give a short description of this methodological and conceptual approach and to apply and to evaluate it in order to show future research potential.
Keywords: design synthesis and optimisation; design methodology; product-oriented process management; matrix based product model; design structure matrix (DSM)

Application of reinforcement learning for the optimization of clinch joint characteristics - Zirngibl, Christoph; Dworschak, Fabian; Schleich, Benjamin; Wartzack, Sandro (Production Engineering, 2021)
Due to increasing challenges in the area of lightweight design, the demand for time- and cost-effective joining technologies is steadily rising. For this, cold-forming processes provide a fast and environmentally friendly alternative to common joining methods, such as welding. However, to ensure a sufficient applicability in combination with a high reliability of the joint connection, not only the selection of a best-fitting process, but also the suitable dimensioning of the individual joint is crucial. Therefore, few studies already investigated the systematic analysis of clinched joints usually focusing on the optimization of particular tool geometries against shear and tensile loading. This mainly involved the application of a meta-model assisted genetic algorithm to define a solution space including Pareto optima with all efficient allocations. However, if the investigation of new process configurations (e. g. changing materials) is necessary, the earlier generated meta-models often reach their limits which can lead to a significantly loss of estimation quality. Thus, it is mainly required to repeat the time-consuming and resource-intensive data sampling process in combination with the following identification of best-fitting meta-modeling algorithms. As a solution to this problem, the combination of Deep and Reinforcement Learning provides high potentials for the determination of optimal solutions without taking labeled input data into consideration. Therefore, the training of an Agent aims not only to predict quality-relevant joint characteristics, but also at learning a policy of how to obtain them. As a result, the parameters of the deep neural networks are adapted to represent the effects of varying tool configurations on the target variables. This provides the definition of a novel approach to analyze and optimize clinch joint characteristics for certain use-case scenarios.
CRIS-Team WoS Importer:2022-01-07

Approach and application to transfer heterogeneous simulation data from finite element analysis to neural networks - Sprügel, Tobias; Bickel, Sebastian; Schleich, Benjamin; Wartzack, Sandro (Journal of Computational Design and Engineering, 2021)
The simulation of product behavior is a vital part of current virtual product development. It can be expected that soon there will be more product simulations due to the availability of easy-to-use finite element analysis software and computational power. Consequently, the amount of accessible new simulation data adds up to the already existing amount. However, even when using easy-to-use finite element software tools, errors can occur during the setup of finite element simulations, and users should be warned about certain mistakes by automatic algorithms. To use the vast amount of available finite element simulations for a data-driven finite element support tool, in this paper, a methodology will be presented to transform different finite element simulations to unified matrices. The procedure is based on the projection of nodes onto a detector sphere, which is converted into a matrix in the next step. The generated matrices represent the simulation and can be described as the DNA of a finite element simulation. They can be used as an input for any machine learning model, such as convolutional neural networks. The essential steps of preprocessing the data and an application with a large dataset are part of this contribution. The trained network can then be used for an automatic plausibility check for new simulations, based on the previous simulation data from the past. This can result in a tool for automatic plausibility checks and can be the backbone for a feedback system for less experienced user
Keywords: plausibility check; finite element simulation; spherical detector surface; deep neural network; convolutional neural network; simulation DNA

Approaches for the assembly simulation of skin model shapes - Schleich, Benjamin; Wartzack, Sandro (Computer-Aided Design, 2015)
Even though they are weakly noticed, geometric part deviations accompany our everyday life. These geometric deviations affect the assemblability and functional compliance of products, since small part variations accumulate through large-scale assemblies and lead to malfunction as well as decreased product reliability and safety. However, the consideration of part deviations in the virtual modelling of mechanical assemblies is an ongoing challenge in computer-aided tolerancing research. This is because the resulting assembly configurations for variant parts are far more complicated than for nominal assemblies. In this contribution, two approaches for the relative positioning of point based models are highlighted and adapted to the assembly simulation of Skin Model Shapes, which are specific workpiece representatives considering geometric deviations. The first approach employs constrained registration techniques to determine the position of variant parts in an assembly considering multiple assembly steps simultaneously, whereas the second utilizes the difference surface to solve the positioning problem sequentially. The application of these approaches to computer-aided tolerancing is demonstrated, though their applicability reaches various fields of industrial geometry.
Keywords: Computer-aided tolerancing; Skin model shapes; Relative positioning; Registration; Assembly simulation; Industrial geometry

Approach for the Automated Analysis of Geometrical Clinch Joint Characteristics - Zirngibl, Christoph; Schleich, Benjamin (Key Engineering Materials, 2021)
Due to their cost-efficiency and environmental friendliness, the demand of mechanical joining processes is constantly rising. However, the dimensioning and design of joints and suitable processes are mainly based on expert knowledge and few experimental data. Therefore, the performance of numerical and experimental studies enables the generation of optimized joining geometries. Nevertheless, the manual evaluation of the results of such studies is often highly time-consuming. As a novel solution, image segmentation and machine learning algorithms provide methods to automate the analysis process. Motivated by this, the paper presents an approach for the automated analysis of geometrical characteristics using clinching as an example.<br
Keywords: Clinch Joints; Geometrical Analysis; Image Segmentation

Approach for the automated and data-based design of mechnical joints. - Zirngibl, Christoph; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the Design Society, 2021)
As a result of the increasing challenges in the field of lightweight constructions, the demand for efficient joining technologies is continuously rising. For this purpose, cold forming processes offer an environmental friendly and fast alternative to established joining methods (e.g. welding). However, to ensure a high reliability, not only the selection of an appropriate procedure, but also the dimensioning of the individual joint is essential. While product designers can rely on a wide range of design principles for thermal processes, the dimensioning and evaluation of mechanical joining processes is mainly based on expert knowledge and a few experimental tests. Although few studies already investigated the numerical analysis of mechanical joints, an approach for the sustainable and consistent optimization of the strength and reliability of joining connections for varying use-cases is not available yet. Motivated by this lack, this paper presents an approach for the automated transfer of information within the process chain and the data-based analysis of mechanical joints by using clinching as an example. Therefore, the CRISP-DM reference model is used for the systematic data mining.<br

Approach for the Reliable and Virtual Design of Mechanical Joints in an Uncertain Environment - Einwag, Jonathan-Markus; Götz, Stefan; Wartzack, Sandro (DS 133: Proceedings of the 35th Symposium Design for X (DFX2024), 2024)
The demand for lightweight assemblies necessitates appropiate joining processes, such as cold forming processes enabling multi-material joints. The absence of universally applicable approaches for the design of mechanical joints makes their initial design iterative and time-consuming. Machine learning based approaches already partly solve this problem, but the impact of uncertainties, is usually neglected. Thus, this contribution proposes the concept of a novel computer-aided approach, supporting the initial design of clinch joints, taking into account uncertainties and varying conditions utilizing numerical simulations, data-driven methods and ontologies. This aims for a high-quality joint design demonstrated using an application scenario where a hat profile and a sheet are joined.<br
Keywords: Mechanical Joining; Clinching; Machine Learning; Finite Element Method; Uncertainties

Approaching an ergonomic future: An affordance-based interaction concept for digital human models - Wolf, Alexander; Krüger, Daniel; Miehling, Jörg; Wartzack, Sandro (Procedia CIRP Volume 84, 2019)
Digital human models offer great potential for the evaluation of physical human factors throughout all phases of product development. Unfortunately, digital human models lack a generic user-product interaction model to use them as universal and truly predictive CAE tools. In this contribution, we propose a concept for a generic and integrated interaction model based on the concept of affordances, the technology of CAD features and posture- and movement-prediction methods. Furthermore, we propose an affordance taxonomy, which shall enable a universal methodical description of interactions occurring during product us
Keywords: user-centered design; user-product interaction; digital human models; affordances; CAD features; human factors

A quality measure for comparing different feature deviations to perform sensitivity analysis in tolerancing - Ziegler, Philipp; Wartzack, Sandro (7th International Conference on Sensitivity Analysis of Model Output 2013, 2013)
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.aquali

A Quantitative Comparison of Tolerance Analysis Approaches for Rigid Mechanical Assemblies - Schleich, Benjamin; Wartzack, Sandro (Procedia CIRP, Volume 43, 2016)
Tolerance analysis is a key tool to predict the consequences of geometric variations on product quality. During the last decades, various approaches for the computer-aided tolerance analysis have been proposed, where each of them has specific advantages and disadvantages. In this contribution, three tolerance analysis approaches, namely tolerance stacks, vector loops, and the tolerance analysis based on the Small Displacement Torsor are quantitatively compared with the tolerance analysis based on Skin Model Shapes considering a typical case study. The novelty of the contribution lies in the profound assessment of these approaches and their results.
Keywords: Tolerance Analysis; Variation Simulation; Skin Model Shapes

A rapid CAE-based design method for modular hybrid truss structures - Walbrun, Simon; Witzgall, Christian; Wartzack, Sandro (Design Science, 2019)
The development of hybrid trusses made of carbon-fiber-reinforced plastic struts and aluminum knots is currently not standardized, and there is no overall method for the design, although it has been proven that mass reduction is feasible. This paper introduces a new method for computer-aided engineering based design of hybrid trusses using carbon-fiber-reinforced plastic struts and metal nodes based on a modular system. The method includes all design steps from topology optimization to computer-aided design model generation and offers support to the engineer. The method is discussed in theory. A case study is done with a beam-shaped truss. It shows that if the bisection optimization method is combined with further constraints, it is suitable for selecting the optimum struts from a modular system for the truss. The developed approach is a suitable method for designing hybrid trusses. The basis of the method has been developed and will be further detailed and extended.
CRIS-Team WoS Importer:2019-12-17

Architecture and realization of a selflearning engineering assistance system for the use within sheetbulk metal forming - Breitsprecher, Thilo; Wartzack, Sandro (Proceedings of the 9th Norddesign, 2012)
UnivIS-Import:2015-04-16:Pub.2012.tech.FT.FT-KLMEFK.archit

Architecture and realization of a self-learning engineering assistance system for the use within sheet-bulk metal forming - Breitsprecher, Thilo; Wartzack, Sandro (NordDesign 2012 - Proceedings of the 9th NordDesign Conference, 2012)
Substantial efforts have been taken in the past to integrate manufacturing related and design-relevant knowledge into the product development process. A common approach is to provide this knowledge to the designer by implementing a knowledge-based system (KBS), an expert system or, as it is referred to in this submission, an engineering assistance system. Keeping the knowledge base of this KBS up to date is a central issue and the necessary knowledge acquisition the bottleneck within the development and maintenance process of a KBS. This applies especially for KBS applications were the knowledge can be considered as dynamic, that is the design- and engineering-relevant knowledge changes within short periods of time. In this paper the emerging manufacturing technology sheet-bulk metal forming (SBMF) is taken as the background for the development and application of an engineering assistance system. To overcome the bottleneck of knowledge acquisition the architecture of the presented assistance system is equipped with a self-learning component, based on knowledge discovery in databases applications.
CRIS-Team Scopus Importer:2020-04-28
Keywords: Engineering assistance system; Knowledge discovery in databases

A Review of Requirements and Approaches for Realistic Visual Perception in Virtual Reality - Gerschütz, Benjamin; Fechter, Marius; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the 22nd International Conference on Engineering Design (ICED19), 2019)
The amount of new virtual reality input and output devices being developed is enormous. Those peripherals offer novel opportunities and possibilities in the industrial context, especially in the product development process. Nevertheless, virtual reality has to face several problems, counteracting reliable use of the technology, especially in ergonomic and aesthetic assessments. In particular, the discrepancies in perception between the real world and virtual reality are of great importance. Therefore, we discuss these most important issues of current virtual reality technology and highlight approaches to solve them. First, we illustrate the use cases of VR in the product development process. In addition, we show which hardware is currently available for professional use and which issues exist with regard to visual perception and interaction. Derived from the depiction of a perfect virtual reality, we define the requirements to address visual perception and interaction. Subsequently we discuss approaches to solve the issues regarding visual perception and evaluate their suitability to enhance the use of virtual reality technology in engineering design.
Keywords: Virtual reality; Visualisation; Visual perception; Eye tracking; Conceptual design

A robust design research landscape - review on the importance of design research for achieving product robustness - Eifler, Tobias; Schleich, Benjamin (Proceedings of the Design Society: International Conference on Engineering Design, 2021)
The strive for design principles, qualitative and quantitative design tools, and product development methodologies that enable and support the design of robust products, that is products which are insensitive to noise and variation, is an ongoing challenge for both practitioners and academics. This paper reviews and classifies recent research efforts dedicated to robust design originating from the design society and carves out important challenges and potentials for future research. The main novelty of the paper can be found in the structured analysis and classification of recent robust design efforts as well as in the systematic elaboration of future research challenges, which seeks to stimulate a discussion on future tasks and challenges in robust design researc
Keywords: Robust design; Tolerance representation and management; Product structuring; Taguchi; Quality

A Semantic Annotation Pipeline towards the Generation of Knowledge Graphs in Tribology - Kügler, Patricia; Marian, Max; Dorsch, Rene; Schleich, Benjamin; Wartzack, Sandro (Lubricants, 2022)
Within the domain of tribology, enterprises and research institutions are constantly working on new concepts, materials, lubricants, or surface technologies for a wide range of applications. This is also reflected in the continuously growing number of publications, which in turn serve as guidance and benchmark for researchers and developers. However, those are almost impossible to keep up with due to their vast quantity and the associated complexity and diversity. Due to the lack of suited data and knowledge bases, knowledge acquisition and aggregation is still a manual process involving the time-consuming review of literature. Therefore, semantic annotation and natural language processing (NLP) techniques can decrease this manual effort by providing a semi-automatic support in knowledge acquisition. The generation of knowledge graphs from textual sources promises improved reuse and retrieval of information acquired from scientific literature in a structured way. Motivated by this, the contribution introduces a novel semantic annotation pipeline for generating knowledge graphs and streamline knowledge acquisition in the domain of tribology. The pipeline is built on BERT, a state-of-the-art language model and involves classic NLP tasks like information extraction, named entity recognition and question answering.<br
Keywords: tribology; tribo-testing; tribo-informatics; machine learning; artificial intelligence; semantic annotation; knowledge graph; natural language processing; tribAIn; BERT

A semantic web approach for structuring data-driven methods in the product development process - Gerschütz, Benjamin; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the 32nd Symposium Design for X (DFX2021), 2021)
For the successful integration of data-driven methods in existing processes, it is first necessary to know these methods and their fields of application, potentials, and individual limits. This requires an easily accessible knowledge base. Depending on possible use cases and available data, this knowledge base should suggest methods that can lead to an optimization of the overall product development process. To prevent the knowledge base from being a rigid catalogue, it is essential to link it to the existing methods of the product development process. This contribution presents an approach based on the semantic web application Semantic MediaWiki, that ensures a connected representation of method knowledge and at the same time enables a link with use cases in the product development proces
Keywords: digital engineering; data-driven-method; design-process; semantic-web

A sensorimotor enhanced neuromusculoskeletal model for simulating postural control of upright standing - Shanbhag, Julian; Fleischmann, Sophie; Wechsler, Iris; Gaßner, Heiko; Winkler, Jürgen; Eskofier, Björn; Koelewijn, Anne; Wartzack, Sandro; Miehling, Jörg (Frontiers in Neuroscience, 2024)
The human's upright standing is a complex control process that is not yet fully understood. Postural control models can provide insights into the body's internal control processes of balance behavior. Using physiologically plausible models can also help explaining pathophysiological motion behavior. In this paper, we introduce a neuromusculoskeletal postural control model using sensor feedback consisting of somatosensory, vestibular and visual information. The sagittal plane model was restricted to effectively six degrees of freedom and consisted of nine muscles per leg. Physiologically plausible neural delays were considered for balance control. We applied forward dynamic simulations and a single shooting approach to generate healthy reactive balance behavior during quiet and perturbed upright standing. Control parameters were optimized to minimize muscle effort. We showed that our model is capable of fulfilling the applied tasks successfully. We observed joint angles and ranges of motion in physiologically plausible ranges and comparable to experimental data. This model represents the starting point for subsequent simulations of pathophysiological postural control behavior.<br
Keywords: postural control; standing; simulation; forward dynamics; neuromusculoskeletal modeling; neural control; motor control; biomechanics

A simple and effective solution of the elastica problem - Campanile, Lucio Flavio; Hasse, Alexander (Proceedings of the Institution of Mechanical Engineers Part C-Journal of Mechanical Engineering Science, 2008)
The bending behaviour of thin stripes and leaf springs, in the presence of large deflections, is ruled by the so-called Bernoulli-Euler equation. The standard solution approach of this problem ('elastica') is represented by the non-linear finite-element analysis. In some special cases, closed-form solutions are available, which involve elliptic integrals and functions. In this article, an alternative method is presented based on the discretization of the deformed beam into circular-arc segments. The method is fast and simple to implement, and therefore suits well for the design and optimization of compliant kinematics. © IMechE 2008.
Keywords: Compliant mechanisms; Elastica; Finite deflections; Non-linear bending

A simplified approach towards integrating biomechanical simulations into engineering environments - Krüger, Daniel; Miehling, Jörg; Wartzack, Sandro (Proceedings of NordDesign 2012, the 9th NordDesign conference, 2012)
In human-centered design biomechanical simulations can be used to predict the characteristics of the interaction between the user and the product in order to optimize the design with respect to ergonomics. However since biomechanical modelling has its origin in medical applications the simulation procedure is not familiar to product designers yet. In this paper an approach towards the integration of an arbitrary biomechanical simulation system into the CAD/CAE engineering environment is proposed. The objective is to enable the analysis of user-product interaction in early design phases based on virtual prototypes. A major focus of this work is the fast acquisition of human body measures and motion sequences using an inexpensive depth imaging device originally designed for entertainment applications
UnivIS-Import:2015-04-16:Pub.2012.tech.FT.FT-KLMEFK.asimpl
Keywords: biomechanics; simulation; human-centred design; ergonomics

A simplified simulation method for adhesively bonded hybrid structures - Witzgall, Christian; Wartzack, Sandro (International Conference on Impact Loading of Structures and Materials, 2016)

A Simulation-Based Approach for the Automated Design of Fatigue Resistant Continuous Fibre-Reinforced Components - Gadinger, Marc; Bode, Christoph; Deutschmann, Torben; Krause, Dieter; Wartzack, Sandro (Proceedings of the 35th Symposium Design for X (DFX2024), 2024)
Fibre-reinforced plastics are increasingly being used in important structural components. Here they are often subjected to cyclic loading, which leads to a deterioration in material properties. However current design methods hardly take this fatigue behavior into account. Instead, they rely on conservative safety factors, resulting in over-dimensioned components. In order to realise the full lightweight potential, we propose an innovative method that enables a targeted design for a defined service life. It integrates knowledge from experimental fatigue testing and uses modified mathematical failure criteria to predict the degree of fatigue throughout the part. This allows us to adaptively reinforce fatigue critical areas, resulting in lightweight and fatigue resistant structure
Keywords: fatigue behavior; fibre-reinforced plastics; lightweight design; optimization

A Simulation-Based Design Approach For Endless-Fiber Reinforced Composite Structures - Klein, Daniel; Völkl, Harald; Wartzack, Sandro (Proceedings of the Seminar "Simulation of Composites - Ready for Industry 4.0", 2016)
The design of endless-fiber reinforced composites is a highly challenging task since the mechanical properties are highly anisotropic and several mutually dependent parameters have to be defined. Therefore product developers have to be supported through design approaches and methods to exploit the whole lightweight potential of this unique material. However, many existing design approaches and methods are restricted to simple geometries and load cases, cause high modelling and computation times or lead to an unstructured design process. For this reason a new design approach is introduced consisting of four consecutive steps. The advantages of this new approach are the resulting structured design process, the low modeling and computational effort and the applicability to arbitrary load cases. The single steps of the design approach as well as its possible results will be demonstrated with the help of the front wing connection of a race car.
Keywords: Leichtbau; Simulation; Konstruktion; Faserverbundwerkstoffe

A Software Tool for the Graph-Based Visualization of Complex Relations Between Product Properties and Characteristics - Luft, Thomas; Schuh, Patricia; Wartzack, Sandro (Research into Design for Communities, Volume 1 Proceedings of ICoRD 2017, 2017)
As products have to meet many different and contradictory requirements, product developers are facing major challenges. The fundamental prerequisite for developing successful products is to understand how desired product properties can be realized by setting appropriate product characteristics. The objective of this paper is to develop a software tool that supports product developers by visualizing the complex network of relations between properties and characteristics. This gives developers a better understanding of the many different relations in product models and can thus make more efficient and more targeted decisions.
Keywords: Design management; Design evaluation; Decision making; Product visualization; Complexity management

Assessment of the Suitability of Selected Linear Actuators for the Implementation of the Load-Adaptive Biological Principle of Redundant Motion Generation - Bartz, Marcel; Jüttner, Michael; Halmos, Fabian; Uhlich, Elias; Klein, Max; Drumm, Patricia; Dreßler, Erkan; Martin, Sina; Walter, Jonas; Franke, Jörg; Wartzack, Sandro (Biomimetics, 2024)
The load-adaptive behavior of the muscles in the human musculoskeletal system offers great potential for minimizing resource and energy requirements in many technical systems, especially in drive technology and robotics. However, the lack of knowledge about suitable technical linear actuators that can reproduce the load-adaptive behavior of biological muscles in technology is a major reason for the lack of successful implementation of this biological principle. In this paper, therefore, the different types of linear actuators are investigated. The focus is particularly on artificial muscles and rope pulls. The study is based on literature, on the one hand, and on two physical demonstrators in the form of articulated robots, on the other hand. The studies show that ropes are currently the best way to imitate the load-adaptive behavior of the biological model in technology. This is especially illustrated in the context of this paper by the discussion of different advantages and disadvantages of the technical linear actuators, where ropes, among other things, have a good mechanical and control behavior, which is very advantageous for use in an adaptive system. Finally, the next steps for future research are outlined to conclude how ropes can be used as linear actuators to transfer load-adaptive lightweight design into technical applications.<br
Keywords: load-adaptive systems; musculoskeletal lightweight design; lightweight design robotics; linear actuators; redundant motion generation; tension chording; cable-driven robotics; rope pulls; artificial muscles

Assistance system for automated and knowledge-based setup and evaluation of design-accompanying Finite Element Analyses - Kestel, Philipp; Sprügel, Tobias; Wartzack, Sandro (Automotive Simulation World Congress, 2016)
Due to growing demands for high functional integration, lightweight-design as well as shorter innovation cycles computer-based simulation techniques, such as FEA (Finite Element Analyses), has become an essential part in automotive development. However, an efficient use of FEA requires early application in the development process. Furthermore, extensive specialist knowledge is a crucial prerequisite to perform reliable simulations. Due to time constraints, design accompanying FEA are performed too rarely by experienced simulation engineers or, if they are applied by non-expert simulation users, are not sufficiently accurate. Thus, a knowledge-based FEA assistance system is presented, to provide the necessary expert knowledge as a function of decisive factors such as the phase in the development process, applied manufacturing processes and analyzed components. The assistance system automates the setup, interpretation and plausibility check of early applied simulations on the basis of the existing CAD (Computer Aided Design) working environment of design engineers, exemplarily implemented for steel construction and die-cast aluminum gear box housings.

Assistenzsystem zur Nutzbarmachung von Systemmodellen für Digitale Zwillinge - Wilking, Fabian (2024)
Angetrieben von den Möglichkeiten der Zustandsüberwachung und neuen Geschäftsmodellen sind Digitale Zwillinge in den letzten Jahren zu einem beliebten Thema in Forschung und industrieller Anwendung geworden. Diese neue Technologie geht jedoch mit einer zunehmenden Komplexität einher, die insbesondere kleine und mittelständische Unternehmen vor große Herausforderungen stellt. Mit dem Model-Based Systems Engineering (MBSE) wurde ein Ansatz geschaffen, um komplexe Systeme beherrschbar zu machen. Die Einführung von MBSE in ein Unternehmen ist allerdings mit erheblichem Aufwand verbunden. Daher suchen Unternehmen nach Kompensationen für diesen Aufwand. Ein Beispiel dafür ist die Wieder- und Weiterverwendung von Modellen, die essenzieller Bestandteil von Digitalen Zwillingen sind. In dieser Arbeit wird ein Ansatz zur Nutzbarmachung von Systemmodellen als Kernmodelle des MBSE im Kontext von Digitalen Zwillingen vorgestellt. Es wird ein Klassifizierungssystem zur Kennzeichnung von Systemmodellen hinsichtlich ihres angestrebten Anwendungsfalls, ihrer Klasse und Einsatz im Lebenszyklus präsentiert, sowie mögliche Szenarien zur Nutzung dieser Systemmodelle für einen Digitalen Zwilling. Daraus wird ein Modellierungsvorgehen abgeleitet, um die Systemmodelle für den Digitalen Zwilling unter Berücksichtigung der Vielfalt unterschiedlicher Klassen und Anwendungsszenarien nutzbar zu machen. Darüber hinaus wird ein Assistenzsystem als Werkzeug vorgestellt, um eine Nutzbarmachung des Systemmodells zu

Assistenzsystem zur Unterstützung der datengetriebenen Produktentwicklung - Küstner, Christof (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2020)
Der digitale Wandel stellt neben der Globalisierung heutzutage eine große Herausforderung für Unternehmen dar. Die Ingenieure sind in diesem Wandel mit neuen Anforderungen an die technischen Produkte und stetig steigender Produktkomplexität konfrontiert. Trotz der vielseitigen Methoden und Werkzeuge, die den Ingenieuren zur Verfügung stehen, können häufig die Einflüsse auf abweichende Produkteigenschaften nicht benannt werden, wodurch die virtuelle Eigenschaftsabsicherung in der Produktentwicklung verhindert oder zumindest erschwert wird. In den vergangenen Jahren haben Methoden aus dem Bereich des maschinellen Lernens ihren Weg in die Produktentwicklung gefunden. Die maschinellen Lernmethoden ermöglichen die Identifikation von Zusammenhängen und Tendenzen in großen Datensätzen. Allerdings fehlt den Produktentwicklern zum einen die Methodenkompetenz zur Entwicklung und Durchführung von Analysen mittels maschineller Lernmethoden. Zum anderen ist Wissen zur vorangestellten Datenaufbereitung und zur Kontextualisierung der identifizierten Muster notwendig. In der vorliegenden Arbeit wird ein Konzept für ein wissensbasiertes Assistenzsystem zur Unterstützung der datengetriebenen Produktentwicklung und dessen Umsetzung vorgestellt. Mithilfe von maschinellen Lernmethoden und deren Integration in bestehende Produktentwicklungsprozesse wird das Potential der datengetriebenen Analysen im Kontext der Eigenschaftsabsicherung offengelegt.<br
Keywords: Datengetriebene Produktentwicklung; Wissensbasiertes Assistenzsystem; Eigenschaftsabsicherung; Produktlebenszyklus; Produktgenerationen; Data-Mining; Machine Learning; produktbeschreibende Daten; Wissen; Assoziationsanalyse

A statistical method to identify main contributing tolerances in assemblability studies based on convex hull techniques - Ziegler, Philipp; Wartzack, Sandro (Proceedings of the 13th CIRP Conference on Computer Aided Tolerancing, 2014)
UnivIS-Import:2015-04-16:Pub.2014.tech.FT.FT-KLMEFK.astati

A survey on the industry’s perception of digital twins – a follow-up to the digital twin workshop at the DESIGN Conference 2022 - Fett, Michel; Zwickler, Julius; Wilking, Fabian; Götz, Stefan; Schweigert-Recksiek, Sebastian; Hicks, Ben; Nespoli, Oscar; Wärmefjord, Kristina; Wartzack, Sandro; Kirchner, Eckhard (Proceedings of the Design Society, 2024)
Digital Twins are perceived differently between and within industry and academia regarding applications and potentials. For this reason, a round table was formed based on the Digital Twin Workshop of the Design Conference 2022. One of the results of this round table is this contribution, which deals with a survey within the industry. The survey captured the understanding of the different roles in the creation and use of Digital Twins, the requirements and hurdles as well as the perception of methodological support. In addition, factors that influence the perception were identified.
CRIS-Team Scopus Importer:2024-05-31
Keywords: design workshop; digital twin; industry 4.0; survey

A SYSTEMATIC COLLECTION OF NATURAL INTERACTIONS FOR IMMERSIVE MODELING FROM BUILDING BLOCKS - Harlan, Jakob; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the International Conference on Engineering Design (ICED21), 2021)
The increased availability of affordable virtual reality hardware in the last years boosted research and development of such systems for many fields of application. While extended reality systems are well established for visualization of product data, immersive authoring tools that can create and modify that data are yet to see widespread productive use. Making use of building blocks, we see the possibility that such tools allow quick expression of spatial concepts, even for non-expert users. Optical hand-tracking technology allows the implementation of this immersive modeling using natural user interfaces. Here the users manipulated the virtual objects with their bare hands. In this work, we present a systematic collection of natural interactions suited for immersive building-block-based modeling systems. The interactions are conceptually described and categorized by the task they fulfi
Keywords: Virtual reality; Conceptual design; Computer Aided Design (CAD)

A systematic literature analysis of influencing factors affecting the balance between usability and emotional product design - van Remmen, Judith Sophie; Wartzack, Sandro; Miehling, Jörg (Journal of Engineering Design, 2025)
In today's competitive market, successful product development hinges on understanding user needs and experiences. With the proliferation of expanding technologies like the Internet of Things, developers can gather vast amounts of data about user interactions. To leverage this wealth of information effectively, a user-centred approach to product development is imperative. This paper explores the convergence of usability and emotional design in product development, examining their interplay and impact on user experience. Through a review of existing literature, it investigates influential factors shaping the prioritisation of usability and emotional design elements. Key questions addressed include identifying these influential factors, assessing their impact on usability and emotional design, and elucidating their interrelationships. By shedding light on these dynamics, this systematic review aims to inform product developers and designers, facilitating the creation of products that resonate with users on both usableand emotional level
Keywords: User-centred design; product design; usability; emotional product design; review

A system for human-in-the-loop simulation of industrial collaborative robot applications - Metzner, Maximilian; Utsch, Daniel; Walter, Matthias; Hofstetter, Christian; Ramer, Christina; Blank, Andreas; Franke, Jörg (IEEE International Conference on Automation Science and Engineering, 2020)
As full automation is often not achievable in flexible production, collaborative robot systems offer potential for an increase in productivity for manual systems. These systems however pose great challenges concerning planning and engineering. We define main requirements for industrial human robot collaboration simulation. It is found that current simulation systems in research and industry cannot sufficiently support the digital planning of such systems. We introduce a framework for a human-in-the-loop system capable of simulation and virtual commissioning of industrial collaborative robot systems. For this, we implement a combined virtual reality, motion capturing and object tracking architecture into an industry standard robot simulation software. We validate our system on real use cases from power electronics production implementing real safety controllers and evaluate the fulfillment of the defined requirements.
Created from Fastlane, Scopus look-up

A transdisciplinary approach to model user-product interaction: how the collaboration between human sciences and engineering design could improve product development for physically impaired people - Krüger, Daniel; Miehling, Jörg; Wartzack, Sandro (International Workshop on the Future of Transdisciplinary Design, 2013)
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.atrans

Ausarbeitungsleitfaden für Nutzerstudien zur Evaluation von XR-Interfaces in der Produktentwicklung - Harlan, Jakob; Schleich, Benjamin; Wartzack, Sandro (Entwerfen Entwickeln Erleben in Produktentwicklung und Design 2021, 2021)
Technologien der erweiterten Realität (extended reality, XR) finden im gesamten Produktentwicklungsprozess Anwendung. Insbesondere Systeme zur aktiven Erzeugung und Veränderung digitaler Produktdaten bieten noch viel Potential. Die Erforschung und Entwicklung dieser immersiven Interfaces beruht maßgeblich auf der Evaluation durch Nutzerstudien, denn nur so kann die Einsatztauglichkeit der Mensch-Maschine-Schnittstellen seriös beurteilt und verglichen werden. Bei der Konzeptionierung und Durchführung dieser Nutzerstudien gibt es viel zu beachten. In dieser Arbeit wird ein Leitfaden für das Design von Evaluationen von XR Interfaces für die Produktentwicklung präsentiert. Zu Beginn müssen die Fragestellungen festgelegt werden, welche die Studie beantworten soll. Ausgehend von die- sen müssen die zu testenden Versuchsbedingungen, die gestellten Aufgaben, die aufgenommen Metriken, die gewählten Probanden und der geplante Ablauf festgelegt werden. Zusätzlich zu der allgemeinen Darlegung wird das Vorgehen anhand eines Fallbeispiels an- gewandt. Die Gestaltung einer Nutzerstudie zur Evaluation der Usability und Eignung eines neuartigen Virtual Reality Interfaces zur natürlichen Gestaltung von Vorentwürfen wird vorgestellt.<br
Keywords: Virtuelle Realität; Erweiterte Realität; Nutzerstudie; Produktentwicklung; Mensch-Maschine-Schnittstelle

Ausgewählte Einflussgrößen auf die erzielbaren Verzahnungstoleranzen beim Kaltfließpressen. - Rohrmoser, Andreas; Heling, Björn; Schleich, Benjamin; Hagenah, Hinnerk; Merklein, Marion (Summer School Toleranzmanagement - Beiträge zur 4. Summer School - September 2020, 2020)

Auslegung eines CFK-Schubfelds über einen simulationsbasierten Ansatz - Völkl, Harald; Schemat, Markus; Weigert, Andreas; Wartzack, Sandro (ATZ - Automobiltechnische Zeitschrift, 2020)
Der Auslegungsprozess von CFK-Strukturen läuft häufig wenig strukturiert ab, ist geprägt von zahlreichen Iterationen und damit zeitaufwändig. Ein neu entwickelter, simulationsbasierter Ansatz kann durch sein strukturiertes Vorgehen helfen, die Auslegung effizienter zu gestalten. In einem Gemeinschaftsprojekt der BMW Group und dem Lehrstuhl für Konstruktionstechnik der Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) wurde der neue Ansatz anhand eines Schubfeldes erprob

Auslegungsgrundlage für die axiale Belastbarkeit von mittels Spannhülsen auf glatten Wellen befestigten Wälzlagern - Tremmel, Stephan; Winkler, Andreas (Konstruktion, 2017)
Adapter sleeves serve for mounting rolling element bearings with tapered bores on cylindrical shafts by forming an interference fit. This article presents detailed rules for calculating the permissible axial load capacity of such a fit. The calculation approach is based on the strength of materials and provides analytical equations. Parameter studies by means of finite element calculations confirm the results of the analytical formula
Keywords: Wälzlager; Rolling Element Bearing; Spannhülse; Spannhülsen; adapter sleeve; adapter sleeves; axiale Belastbarkeit; axial load capacity; Festigkeitslehre

Auslegung und Gestaltung additiv gefertigter Bauteile - Wartzack, Sandro; Wittmann, Stefan; Stuppy, Julia; Tremmel, Stephan (Additive Fertigung, 2009)
UnivIS-Import:2015-04-16:Pub.2009.tech.FT.FT-KLMEFK.ausleg

Auslegung von amorphen Kohlenstoffschichten für Knie-Totalendoprothesen - Wartzack, Sandro; Rothammer, Benedict; Marian, Max; Wolf, Alexander; Miehling, Jörg; Tremmel, Stephan (WiGeP News, 2019)

Auslegung von CFK-Strukturen – ein neuer Ansatz - Klein, Daniel; Kieser, Christoph; Wartzack, Sandro (Lightweight Design, 2016)
Die Auslegung von CFK-Strukturen ist ein oft unstrukturierter Prozess, der von zahlreichen Iterationen geprägt ist und ein hohes Maß an Erfahrung erfordert. Im Rahmen der Entwicklung einer Frontflügelanbindung in CFK-Sandwich-Bauweise wurde deshalb der neuentwickelte Ansatz mfkCODE angewendet, der eine strukturierte Auslegung beanspruchungsgerechter CFK-Bauteile erlaubt.
Keywords: Leichtbau; Faserverbundwerkstoffe; Simulation

Auslegung von Traversen für Hochleistungsbestückautomaten aus zellularen metallischen Werkstoffen - Puri, Werner; Schmidt, Winfried; Meerkamm, Harald; Schweiger, Willy; Singer, Robert; Heinrich, Frank (VDI-Berichte, 2001)
UnivIS-Import:2015-04-20:Pub.2001.tech.FT.FT-KLMEFK.ausleg

Auswirkungen von laserstrukturierten Substratoberflächen auf die tribologischen Eigenschaften beschichteter Gleitpaarungen - Seitz, Alexander; Tremmel, Stephan; Meerkamm, Harald (Tribologie und Schmierungstechnik, 2006)
UnivIS-Import:2015-03-09:Pub.2006.tech.FT.FT-KLMEFK.auswir_3

Auswirkungen von passungsbedingten Deformationen auf das Radialspiel von Wälzlagerungen - Aschenbrenner, Alexander; Heling, Björn; Wartzack, Sandro (Summer School Toleranzmanagement - Beiträge zur 2. Summer School - September 2015, 2015)
Keywords: Statistische Toleranzanalyse; Toleranz; Wälzlager; Radialspiel

Auswirkung von laserstrukturierten Substratoberflächen auf die tribologischen Eigenschaften beschichteter Gleitpaarungen - Seitz, Alexander; Meerkamm, Harald; Tremmel, Stephan (47. Tribologie-Fachtagung. Reibung, Schmierung und Verschleiß, 2005)
UnivIS-Import:2015-04-16:Pub.2005.tech.FT.FT-KLMEFK.auswir

Auswirkung von Oberflächenmodifikationen auf die Lebensdauer hoch belasteter Gleitführungen in modernen Diesel-Einspritzsystemen - Seitz, Alexander; Meerkamm, Harald; Tremmel, Stephan (Gleit- und Wälzlagerungen. Gestaltung, Berechnung, Einsatz., 2006)
UnivIS-Import:2015-04-16:Pub.2006.tech.FT.FT-KLMEFK.auswir

Automated point-based tolerance analysis model creation for sheet metal parts - Litwa, Frank; Gottwald, M; Bohn, M; Klinger, J; Walter, Michael; Wartzack, Sandro; Vielhaber, M (Proceedings of the 13th CIRP Conference on Computer Aided Tolerancing, 2014)
UnivIS-Import:2015-04-16:Pub.2014.tech.FT.FT-KLMEFK.automa

Automatic derivation of use case diagrams from interrelated natural language requirements - Schleifer, Simon; Lungu, Adriana; Kruse, Benjamin; van Putten, Sebastiaan; Götz, Stefan; Wartzack, Sandro (DESIGN 2024, 2024)
Keywords: requirements management; model-based systems engineering (MBSE); artificial intelligence (AI); natural language processing (NLP); use case diagrams

Automotive Premium Quality Improvement by High-End-Visualization - Striegel, Serena; Schleich, Benjamin; Zielinski, Daniel; Wartzack, Sandro (ASME 2017 International Mechanical Engineering Congress and Exposition, Volume 2: Advanced Manufacturing, 2017)
Volatile markets, tough customer expectations, and short product life cycles are just some of the challenges the automotive industry has to deal with. In this context, important quality features are expressed as key product characteristics (KPC). The process of defining and reviewing such KPCs concerns each department of an automobile company. This paper presents a method for an intersubjective problem understanding of inter-divisional working groups and a common product KPC’s definition. The scientific contribution lies in the field of quality assessment for the premium-segment automotive industry, while the novelty can be found in providing the opportunity to take quality decisions based on variation simulations and on high-end-visualizations. The proposed method aims to realize and implement a higher premium quality standard and, at the same time, to reduce the number of physical prototypes, to shorten development times and to facilitate an intersubjective problem understanding. In relation to the developed method, an industrial application and its results are presented.
Keywords: Visualisation

A variational simulation framework for the analysis of load distribution and radial displacement of cylindrical roller bearings - Aschenbrenner, Alexander; Schleich, Benjamin; Tremmel, Stephan; Wartzack, Sandro (Mechanism and Machine Theory, 2020)
In many technical systems, rolling bearings are critical machine elements concerning accuracy and lifetime. Their load distribution and radial displacement are directly linked to the accuracy and the fatigue life of rolling bearings. However, load distribution and radial displacement form a complex interdependency. Geometric deviations further influence this mutual connection. Although there are several approaches to determine the load distribution and the radial displacement, most of them are either too simplistic, allowing only the consideration of dimensional deviations, or too sophisticated and therefore unsuitable for a statistical evaluation of geometric deviations. Hence, the main purpose of this contribution is to provide a method for the determination of load distribution and radial displacement of cylindrical roller bearings that allows the consideration of geometric deviations as well as statistical evaluation of these deviations. Moreover, applying the method to a use case shows, whether the consideration of geometric deviations in the determination of load distribution and radial displacement is reasonable. The novelty of the contribution is, therefore, the provision of a statistical variational simulation framework for the analysis of load distribution and radial displacement of rolling bearing
Keywords: Geometric variation simulation; Rolling bearing; Tolerance analysis; Load distribution; Radial deflection; Internal bearing clearance

A visualization methodology for evaluating parts made of short fiber reinforced thermoplastics regarding their lightweight potential - Gruber, Georg; Wartzack, Sandro; Kößler, Johannes (Proceedings of the 19th International Conference on Engineering Design, 2013)
Injection molded, short fiber reinforced thermoplastics are a promising lightweight material. However, the component design is getting complex with this type of material due to the process induced fiber orientation. To achieve substantial progress in lightweight design, the resulting anisotropic material properties have to be taken advantage of effectively. The most important correcting variables influencing the fiber orientation are the part's geometry and the gate design (position and type of gates). The goal of the present paper is introducing a new evaluation method, supporting the product developer at detecting the most appropriate geometry and gate layout. The basic idea behind the new approach is examining the deviations between the load path and the fiber orientation pattern. With the help of new quality criteria it can be rated to which extent load path and fiber orientation are in harmony. The methodology is implemented as a software tool, delivering a mean quality criterion per part as well as a contour plot enabling also the analysis of the local distribution of the focused quality criterion. The potential of the new approach is demonstrated within a brief case study.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.avisua
Keywords: Decision making; Lightweight design; Short fiber reinforced thermoplastics; Simulation; Visualization

Avoidance of unnecessary design iterations by monitoring the product´s degree of maturity - Krehmer, Hartmut; Meerkamm, Harald; Wartzack, Sandro (Proceedings of the 11th International Design Conference DESIGN 2010, 2010)
Increasing requirements as well as product development processes getting more and more complex cause an increased likelihood of unneccessary design iterations. So, developers need a framework to avoid unnecessary and time-consuming detours by assessing effects of each possible change. Aim of this contribution is to identify key factors for the avoidance of unnecessary iterations and to present approaches for coping these challenges. Furthermore a framework for the avoidance of unnecessary iterations based on a continuous monitoring the product's degree of maturity is introduced.
UnivIS-Import:2015-04-16:Pub.2010.tech.FT.FT-KLMEFK.avoida
Keywords: Characteristics; Design iterations; Product's degree of maturity; Properties

Baukastensystem für CFK-Fachwerkstrukturen – Diskrete Optimierung der Strebenquerschnitte - Walbrun, Simon; Wartzack, Sandro (Design for X - Beiträge zum 30. DfX-Symposium, 2019)
Fiber-reinforced plastics have a high potential for lightweight structures due to their high specific strength and stiffness. A modular system enables a reduction of the manufacturing costs for trusses by standardizing the components. The subdivision of the truss struts into groups and the selection of the profiles for the strut groups can be done by optimization with a genetic algorithm and the initial population generation by the bisection method. The proposed method reduces the number of necessary iterations and improves the optimum in comparison to the previous descriptions
Keywords: Genetic algorithms; Initial population; Optimization; Self-adaptive member grouping

Beam-colored Sketch and Image-based 3D Continuous Wireframe Reconstruction with different Materials and Cross-Sections - Denk, Martin; Rother, Klemens; Paetzold, Kristin (Entwerfen Entwickeln Erleben - EEE2021, 2021)
The automated reverse engineering of wireframes is a common task in topology optimization, fast concept design, bionic and point cloud reconstruction. This article deals with the usage of skeleton-based reconstruction of sketches in 2D images. The result leads to a flexible at least C₁ continuous shape description.<br
Keywords: Reverse Engineering; Fast Concept Design; Skeleton

Behavior of Lubricated Bearings in Electric Circuits - Kirchner, Eckhard; Bartz, Marcel; Becker-Dombrowsky, Florian (Lubricants, 2024)

Berechnung beanspruchungsgerechter Faserorientierungen in CFK-Strukturen - Klein, Daniel; Caballero, Steffen; Wartzack, Sandro (ANSYS Conference & 31th CADFEM Users Meeting, 2013)
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.berech
Keywords: Leichtbau; Composites; Simulation

Berechnung beanspruchungsgerechter Patch-Geometrien für die Auslegung von CFK-Strukturen in den frühen Phasen der Produktentwicklung - Klein, Daniel; Scheler, Kaja; Wartzack, Sandro (kunststoffe + SIMULATION 2014, 2014)
Keywords: Leichtbau; Composites

Berechnung und Analyse von Reibmoment- und Temperaturverlauf von Wälzlagern unter Drehzahl- und Lastkollektiven - Stahl, Thomas; Tremmel, Stephan; Wartzack, Sandro; Meerkamm, Harald (VDI-Fachtagung Gleit- und Wälzlagerungen 2011: Gestaltung, Berechnung, Einsatz (VDI-Berichte 2147), 2011)
Der Beitrag beschreibt einen Berechungsalgorithmus zur Ermittlung der Wälzlagerreibung unter Berücksichtigung von Drehzahl- und Lastkollektiven. Hierzu werden die grundlegenden Vorgänge der Wärmedissipation an einer Wälzlagerung und deren Zusammenhänge aufgezeigt, sowie Berechnungsmöglichkeiten der einzelnen Wärmeströme vorgestellt. Dabei wird auch die Einbauumgebung berücksichtigt, da die Wärmedissipation über Gehäuse, Welle, Fundament und weiteren damit in Kontakt stehenden Bauteilen die Temperatur im Lager maßgeblich beeinflusst. Anschließend werden die Ergebnisse dieser Berechnung mit den Messwerten der experimentellen Validierung gegenübergestellt. In diesem Zusammenhang wird gezeigt, wie sich unterschiedliche Kollektivausprägungen und Lagerparameter auf Reibung und Temperatur auswirken. Abschließend wird der „Bearing Friction Calculator“ vorgestellt. Ein Software-Werkzeug, das es dem Konstrukteur erlaubt, bereits in frühen Phasen des Produktentwicklungsprozesses die entstehende Reibung und Temperatur im Wälzlager unter Berücksichtung von Drehzahl- und Lastkollektiven zu ermitteln, um so eine optimierte Auslegung der Wälzlagerung durchführen zu können.
UnivIS-Import:2015-04-16:Pub.2011.tech.FT.FT-KLMEFK.berech
Keywords: Reibungsberechnung; Wärmeübertragung; Reibungsmessung; Kollektivparameter; Wälzlagerauslegung

Berücksichtigung biomechanischer Zusammenhänge in der nutzergruppenspezifischen virtuellen Produktentwicklung - Miehling, Jörg (VDI Verlag, 2018)

Berücksichtigung der Physiologie und Einstellung von Nutzern mittels Integration externer Einflussfaktoren in Affective Engineering Methoden - van Remmen, Judith Sophie; Miehling, Jörg; Wartzack, Sandro (Entwerfen Entwickeln Erleben 2024 Menschen, Technik und Methoden in Produktentwicklung und Design 2024, 2024)
<dl> In der nutzerzentrierten Produktentwicklung wird der Mensch als Summe seiner individuellen physiologischen und psychologischen Ausprägungen verstanden, welche in persönlichen Bedürfnissen an das Produkt resultieren. Diese können auch als affektive Ansprüche definiert werden und sind folglich Anforderungen, die sich aus den individuellen, subjektiven Erwartungen ergeben. Das Affective Engineering (AE) stellt die Verbindung zwischen diesen Anforderungen und dem Produktdesign her und berücksichtigt die affektiven Bedürfnisse der Nutzer sowie deren affektive Zufriedenheit zur Entwicklung erfolgreicher Produkte und stellt somit die User Experience (UX) in den Fokus. Derzeit werden externe Einflussfaktoren wie z. B. das Alter oder die Kultur in bestehenden AE-Methoden nur bedingt berücksichtigt. In diesem Beitrag wird daher anhand einer beispielhaften AE-Methode „ACADE +P“ die Integration externer Einflussfaktoren und dessen Nutzen forciert. </dl>
Keywords: Nutzer-Produkt-Interaktion; User Experience; Affective Engineering

Berücksichtigung der Schmierstoffhydrodynamik in der Käfigführung bei der Wälzlagerdynamiksimulation - Seiler, Katrin; Stadler, Marion; Tremmel, Stephan; Hahn, Bodo; Graf-Goller, Oliver; Wartzack, Sandro (SMK2014 Schweizer Maschinenelemente Kolloquium, 2014)
Bei Wälzlagern die zum Beispiel hohen Zentripetalbeschleunigungen ausgesetzt sind, kann die Reibung an den Käfigkontakten sehr stark zunehmen. Die Schmierstoffhydrodynamik in den Käfigkontakten ist in diesen Fällen in der Wälzlagermehrkörpersimulation zu berücksichtigen. Hierbei reicht es im Fall des Käfig/Außenring-Kontakts nicht aus, ausschließlich den hydrodynamischen Kontakt an den Käfigstirnringen zu berücksichtigen. Um die Käfigführung realistisch darstellen zu können, ist zusätzlich der Kontakt an den Käfigstegen, an denen ebenfalls hydrodynamische Effekte Einfluss haben, abzubilden. Der Beitrag stellt analytische Berechnungsmodelle für die Abbildung der Hydrodynamik an den Stegen im Käfig/Ring-Kontakt vor. Die Modelle beinhalten die Berechnung der Normalkraft, der Schmierstoffdämpfung und der Reibung aufgrund der Schmierstoffscherung. Die Berechnungsmodelle wurden in das Wälzlagermehrkörpersimulationsprogramm CABA3D implementiert und mit dem Gleitlagerberechnungsprogramm COMBROS abgeglichen. Anhand neuer Simulationsergebnisse wird im Beitrag der Einfluss der Hydrodynamik auf das Lagergesamtreibmoment und die Lagerkinematik dargestellt.
Keywords: Wälzlager; MKS; Tribologie; Hydrodynamik

Berücksichtigung von produktionsspezifischen Abweichungen im interdisziplinären Toleranzmanagement - Heling, Björn; Oberleiter, Thomas; Rohrmoser, Andreas; Kiener, Christoph; Schleich, Benjamin; Hagenah, Hinnerk; Merklein, Marion; Willner, Kai; Wartzack, Sandro (Industriekolloquium der Forschergruppe FOR 2271, 2019)
LFT Import::2019-08-05 (2353)

Berücksichtigung von Wechselwirkungen zwischen Abweichungen in der statistischen Toleranzanalyse - Walter, Michael; Sprügel, Tobias; Ziegler, Philipp; Wartzack, Sandro (Konstruktion, 2015)
Die Toleranzanalyse ermöglicht dem Konstrukteur die quantitative Beurteilung der Auswirkungen von Abweichungen auf Funktion und Ästhetik eines Produktes; unter anderem anhand der sogenannten Beitragsleister. Jedoch erlauben bisherige Methoden der Beitragsleister-Analyse lediglich die Berücksichtigung direkter Auswirkungen der Abweichungen; mögliche Wechselwirkungen zwischen Abweichungen und deren Auswirkungen bleiben somit unberücksichtigt. Dieser Beitrag widmet sich dem Einsatz der globalen Sensitivitätsanalyse zur Berechnung der Beitragsleister. Diese ermöglicht die Bestimmung der direkten Effekte der Abweichungen als auch deren indirekte Effekte aufgrund von Wechselwirkungen zwischen Abweichungen.
Keywords: Wechselwirkungen zwischen Abweichungen; Statistische Toleranzanalyse; varianzbasierte Sensitivitätsanalyse; Toleranz-Kosten-Kurven

Berücksichtigung vorausgegangener Ermüdungsschädigung in der Crashsimulation kurzfaserverstärkter Thermoplaste - Witzgall, Christian (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2025)
Bauteile aus kurzfaserverstärkten Thermoplasten werden im Fahrzeugbau zunehmend in Funktionen eingesetzt, bei denen sie sowohl während der normalen Gebrauchsdauer beansprucht als auch ihr Verhalten im Crash von Bedeutung ist. Die durch wiederholte Beanspruchung infolge der Gebrauchslastfälle auftretende Ermüdungsschädigung führt zu einer Verschlechterung der mechanischen Eigenschaften, wird jedoch gegenwärtig in der Crashsimulation nicht berücksichtigt. Hier setzt die vorliegende Arbeit an: sie stellt einen Ansatz vor, der durch geeignete experimentelle Charakterisierungsverfahren die Materialdegradation infolge zyklischer Beanspruchung quantifizieren und ihre Auswirkungen auf crashrelevante Werkstoffeigenschaften modellieren soll. Diese veränderten Werkstoffkennwerte werden der Crashsimulation je nach vorherrschender Schädigung übergeben. Die notwendigen Modelle werden durch Betrachtungen an Zugstäben hergeleitet und in Biegeversuche an Kreuzrippenträgern validiert. Der vorgestellte Ansatz zeigt hierbei eine gute Prognosefähigkeit, deren Diskussion und Ausblick auf weitere Potentiale den Abschluss der Arbeit darstell

Berücksichtigung zyklischer Materialdegradation in der crashsimulation kurzfaserverstärkter Thermoplaste - Witzgall, Christian; Huber, Martin; Wartzack, Sandro (Konstruktion, 2020)
Everything ages – including components made of short-fibre-reinforced plastic, which are frequently used in modern vehicle design. A thousand times repeated mechanical stress from service load cases leads to a degradation of the mechanical properties, which influences the crash behaviour of the structure. However, this effect is currently not taken into account in the assessment of crash safety due to the use of material data obtained from material samples in new condition. The present article therefore presents a method that allows the effects of this material degradation to be taken into account in numerical crash simulation – and thus an assessment of crash safety in various phases of life.

Beschichtete Kunststoffe für funktionsintegrierte Leichtbaulösungen - Sander, Thomas; Tremmel, Stephan; Wartzack, Sandro (Konstruktion, 2014)
UnivIS-Import:2015-03-09:Pub.2014.tech.FT.FT-KLMEFK.beschi

Besonderheiten bei der Auslegung und Gestaltung lasergesinterter Bauteile - Wartzack, Sandro; Drummer, Dietmar; Wittmann, Stefan; Stuppy, Julia; Rietzel, Dominik; Tremmel, Stephan; Kühnlein, Florian (RTejournal - Forum für Rapid Technologie, 2010)
UnivIS-Import:2015-03-09:Pub.2010.tech.FT.FT-KLMEFK.besond

Bestimmung und Berücksichtigung der Einzelpunktmessunsicherheit in virtuellen Toleranzanalysen - Heling, Björn; Müller, Andreas; Schleich, Benjamin; Hausotte, Tino; Wartzack, Sandro (Summer School Toleranzmanagement - Beiträge zur 4. Summer School - September 2020, 2020)

Bewertung und Optimierung der Faserverbundeignung von Leichtbaustrukturen in den frühen Phasen der Produktentwicklung - Klein, Daniel; Witzgall, Christian; Wartzack, Sandro (NAFEMS Online-Magazin, 2014)
Die Auslegung von Produkten aus faserverstärktem Kunststoff (FVK) stellt an Produktentwick-ler besonders hohe Anforderungen, denn nur wenn es gelingt, die Fasern richtig zu belasten, kann das Leichtbaupotential von FVK ausgenutzt werden. Dabei ist es zwingend erforderlich, dass bereits in den frühen Phasen der Produktentwicklung das Bauteildesign kritisch in Bezug auf dessen Eignung für FVK hinterfragt wird. Eignet sich ein Bauteil aufgrund seiner Geometrie oder der Belastungsart nicht, kann dies selbst durch die beste Auslegung und Simulation nicht mehr ausgeglichen werden. In dem folgenden Beitrag wird ein erster Algorithmus vorgestellt, der es erlaubt, basierend auf einfachen FE-Simulationen mit isotropem Materialmodell, die Faserverbundeignung von Leichtbaustrukturen zu berechnen und zu visualisieren. Dazu werden über bewährte Theorien, wie etwa der klassischen Laminattheorie, Kriterien hergeleitet und diskutiert, die zusammen die Bewertung eines Bauteils zulassen. Ziel des Bewertungsalgorithmus ist es, zum einen eine Aussage über die generelle Eignung der Struktur für einen FVK zu geben und zum anderen auch Bereiche anzudeuten, die noch optimiert werden müssen. Am Ende des Beitrags wird gezeigt, dass so Verbesserungspotentiale abgeleitet werden können, die zu einer signifikanten Optimierung der Bauteileigenschaften führen. Es ist an dieser Stelle unbedingt zu erwähnen, dass das Hauptaugenmerk dieses Beitrags auf endlos-kohlefaserverstärktem Kunststoff (CFK) liegt. Weite Teile des Beitrags können aber direkt auf viele unterschiedliche FVK übertragen werden.
UnivIS-Import:2015-10-26:Pub.2014.tech.FT.FT-KLMEFK.bewert

Beyond Predictive Maintenance und Condition Monitoring: Mit smarten Systemen in der Tribologie und Antriebstechnik Reibung und Verschleiß minimieren um die Nachhaltigkeit zu verbessern. - Bartz, Marcel (Eröffnung des Forschungszentrums für das Engineering Smarter Produkt-Service-Systeme (ZESS), 2023)

Biomechanical Digital Human Models: Chances and Challenges to Expand Ergonomic Evaluation - Peters, Markus; Quadrat, Eric; Nolte, Alexander; Wolf, Alexander; Miehling, Jörg; Wartzack, Sandro; Leidholdt, Wolfgang; Bauer, Sebastian; Fritzsche, Lars; Wischniewski, Sascha; et al. (Human Systems Engineering and Design, 2018)
Nowadays, ergonomic evaluation of work can be done using Digital Human Models (DHM). One advantage is to reduce the need for corrective measures by supporting a more prospective ergonomic work design. Although ergonomic models provide useful information for risk assessment, single working tasks with minor changes in work place design are difficult to evaluate. Instead, biomechanical models can analyze single movements or body postures, taking internal forces in muscles and joints into account. Therefore, the main goal of this work is to establish an interface between a biomechanical human model (AnyBody) and the “Editor for manual work activities” (ema) to enrich ergonomic evaluation with biomechanical parameters. First results demonstrate that the automatically generated movements of ema showed some specific deviations relative to the subjects’ movements in experimental conditions. Optimization of kinematic data in AnyBody is necessary to ensure more physiological movements which are highly valuable for ergonomic evaluatio
Keywords: Human factors; Digital Human Models; Ergonomics; Biomechanics; Anthropometry; Risk assessment

Biomechanische Betrachtungen der Berechnung von Kräften mit Menschmodellen - Eicker, Henrik; Gößling, Rainer; Bartz, Marcel; Bender, Beate (Design for X: Beiträge zum 25. DfX-Symposium, 2014)

Biomechanischer Simulator zur prä-operativen Abschätzung und Optimierung der post-operativen Muskelfunktion am Beispiel der Revisionsendoprothetik des Hüftgelenks - Miehling, Jörg; Forst, Raimund; Wartzack, Sandro; Sesselmann, Stefan (Deutscher Kongress für Orthopädie und Unfallchirurgie - PO11 Beste klinische Abstracts, 2016)
Fragestellung: Die Anzahl der operierten Hüft- und Knie-Totalendoprothesen (TEP) in Deutschland steigt immer weiter an. Auch die Revisionsendoprothetik gewinnt immer mehr an Bedeutung. Dabei wird versucht, die gelenkanatomischen Parameter zu rekonstruieren. Biomechanische Parameter der Muskulatur finden in der präoperativen Planung kaum Berücksichtigung. Vor allem bei Revisionsimplantaten des Hüftgelenks können die ursprüngliche Gelenksgeometrie und defekte Muskelansätze aber häufig nicht rekonstruiert werden. Die Rehabilitation verlängert sich dadurch deutlich oder ist nicht mehr vollständig möglich. Daraus ergibt sich die Frage, ob und wie biomechanische Simulationen dazu beitragen können, den Operateur in der Planung zu unterstützen, sodass der Patient nach der OP geringstmöglich in seiner Lebensführung eingeschränkt ist. Methodik: Um den Einfluss der Implantatgeometrie sowie der anatomischen Gegebenheiten im Revisionsfall auf die Muskelfunktion abschätzen und optimieren zu können, wurde ein biomechanischer Simulator entwickelt. Das Muskel-Skelett-System des Menschen wird als durch Muskeln aktuiertes biomechanisches Mehrkörper-System nachgebildet. Die Gelenk- und Muskelgeometrie kann beliebig variiert werden. Beim vorgestellten Hüft-Simulator wird die Position des Trochanter major bezüglich des Drehzentrums sowie die Position der Hüftpfanne im Becken in kartesischen Koordinaten beschrieben. Aus der Trochanter-Position können CCD-Winkel, AT-Winkel, Offset und Beinlängendifferenz berechnet werden. Der Simulator kann nun den Einfluss der kinematischen Veränderungen durch das simulierte Kunstgelenk auf die Drehmomenterzeugung der einzelnen Muskelstränge in einer bestimmten Körperhaltung oder Bewegung berechnen. Defekte Muskeln oder Muskelanteile sind durch die Software ebenfalls simulierbar. Für die Hüftsimulation wurde der einbeinige Stand gewählt, da dieser der Standphase beim Gehen stark ähnelt. Ergebnisse und Schlussfolgerung: Die durchgeführten Simulationen zeigen, dass biomechanische Betrachtungen in die vorhandenen Tools zur Operationsplanung integriert werden sollten. Dem Operateur kann ein Werkzeug an die Hand gegeben werden, das ihn bezüglich der Biomechanik schon bei der Planung einer TEP unter Berücksichtigung der anatomischen Gegebenheiten sinnvolle Parameterbereiche erkennen lässt. Bereits kleine Veränderungen in der Positionierung der Implantate können dabei zu beträchtlichen Unterschieden in der Momenterzeugung durch die beteiligten Muskeln führen.
Keywords: Biomechanische Simulation; Muskelfunktion; Endoprothetik; Revision; Hüfte

Biomimetics Linked to Classical Product Development: An Interdisciplinary Endeavor to Develop a Technical Standard - Wanieck, Kristina; Hamann, Leandra; Bartz, Marcel; Uttich, Eike; Hollermann, Markus; Drack, Manfred; Beismann, Heike (Biomimetics, 2022)
Biomimetics is a well-known approach for technical innovation. However, most of its influence remains in the academic field. One option for increasing its application in the practice of technical design is to enhance the use of the biomimetic process with a step-by-step standard, building a bridge to common engineering procedures. This article presents the endeavor of an interdisciplinary expert panel from the fields of biology, engineering science, and industry to develop a standard that links biomimetics to the classical processes of product development and engineering design. This new standard, VDI 6220 Part 2, proposes a process description that is compatible and connectable to classical approaches in engineering design. The standard encompasses both the solution-based and the problem-driven process of biomimetics. It is intended to be used in any product development process for more biomimetic applications in the future.<br
Keywords: innovation; product development; process; solution finding; workflow

Biotribological behavior of amorphous carbon coatings on Co28Cr6Mo alloy and UHMWPE - Neusser, Kevin; Rothammer, Benedict; Marian, Max; Bartz, Marcel; Wartzack, Sandro (4th YOUNG TRIBOLOGICAL RESEARCHER SYMPOSIUM, 2021)
Endoprosthetic replacement of the joint intends to restore the functionality and to provide the patient with a pain-free and more mobile life. However, aseptic loosening of the total knee arthroplasty (TKA) is a major cause of early prosthesis failure and is multifactorial in etiology with wear debris removed from the implant materials being largely responsible. For this reason, a great effort is made to reduce polymeric inlay wear by applying tribologically effective surface modifications. Thus, this study concentrated on the effectiveness of wear-reducing amorphous carbon coating systems on the materials Co28Cr6Mo and UHMWPE. The tribological impact of the carbon coating systems can be particularly enhanced by a good adhesion to the substrate. Therefore, specific attention was also paid to the investigation of adhesion. The tribological behavior of the coated material pairings in comparison to the uncoated pairings was investigated utilizing a climate-controlled pin-on-disc tribometer in rotational sliding mode. The tribological behavior was studied under mixed lubrications conditions for a total number of 200 000 sliding cycles. Bovine serum, tempered to 37 °C, was used as a substitute synovial fluid. The wear rates were determined using light and laser scanning microscopy every 20 000 cycles. Thereby, various wear mechanisms were detected, which in turn affected the coefficient of friction. The strong wear traces on UHMWPE indicated abrasive and adhesive wear. Consequently, the present study showed the applicability of well-adhering coatings to the considered materials used for applications in medical technology and the potential for wear reduction. Furthermore, the tribological characteristics obtained serve as a basis for further development of the coating systems.<br

Biotribological behavior of amorphous carbon coatings on Co28Cr6Mo alloy and UHMWPE under boundary friction conditions in sliding contact - Neusser, Kevin; Rothammer, Benedict; Marian, Max; Bartz, Marcel; Wartzack, Sandro (62. Tribologie-Fachtagung. Reibung, Schmierung und Verschleiß. Forschung und praktische Anwendungen., 2021)
Zusammenfassung: Nach einem Knie-Gelenkersatz wirkt sich Verschleiß infolge biotribologischer Vorgänge maßgeblich auf die Standzeit von Totalendoprothesen (TEP) aus. Aufgrund freigesetzter Abriebpartikel, insbesondere aus dem Kunststoff-Inlay der Tibia-Komponente, kommt es häufig zu Knochenabbaureaktion im periprothetischen Knochengewebe der Prothesenverankerung und somit zu einer aseptischen Lockerung. Ansätze hinsichtlich der Beschichtung artikulierender Oberflächen mit amorphen Kohlenstoffschichten (DLC) stellen Bemühungen dar, den Verschleißprozessen biokompatibel entgegenzuwirken. In diesem Beitrag wird die tribologische Wirksamkeit amorpher Kohlenstoffschichtsysteme in einem abstrahierten biotribologischen Versuch unter körpernahen Randbedingungen und Belastungskollektiven mittels eines Stift/Scheibe-Tribometers aufgezeigt. Abstract: Wear due to biotribological processes has a considerable influence on the service life of a total knee replacement. Released abrasion particles, especially from the polymeric inlay of the tibial component, may cause bone resorption in the periprosthetic bone tissue, leading to aseptic loosening. Introducing a tribologically effective diamond-like carbon (DLC) coating to the articulating surfaces represents an approach to prevent wear processes in a biocompatible manner. In this study, the tribological effectiveness of amorphous carbon coating systems is evaluated using an abstracted pin-on-disk experiment under near-body boundary conditions and load collectives.
Keywords: Total knee replacement; DLC coating; biotribology; wear; biocompatibility; UHMWPE; pin-on-disk

Biotribological behavior of MXene-UHMWPE composites - Marian, Max; Feile, Klara; Rothammer, Benedict; Bartz, Marcel; Wartzack, Sandro; Rosenkranz, Andreas (77th STLE Annual Meeting & Exhibition, 2023)
MXenes are a relatively new class of 2D transition metal carbides, nitridesand carbonitrides receiving increasing attention in tribologicalapplications due to their self-lubricating character. A prospectiveapplication of MXenes is their addition to UHMWPE with the overallpurpose to improve the biotribological behavior of polymericcomponents of load-bearing implants. Within this study, Ti3C2Tx-UHMWPE composites with varying MXene content were biotribologicallyanalyzed using pin-on-disk tribometer tests. Thereby, a friction reductionby up to 22% compared to pure UHMWPE was demonstrated. Thedetermined wear rates of the disks considerably decreased by up to 43%due to the addition of MXenes. Furthermore, the composite-disksreduced the wear rates of the tested CoCr-pins by up to 19%. Both the reduction of friction and wear underline the great potential of MXenes asa reinforcement phase in UHMWPE to improve the biotribologicalbehavior and service life of biomedical applicatio

Biotribological behavior of MXene-UHMWPE-composites for total knee arthroplasty - Feile, Klara; Rothammer, Benedict; Bartz, Marcel; Wartzack, Sandro; Marian, Max (5th YOUNG TRIBOLOGICAL RESEARCHER SYMPOSIUM, 2022)
MXenes are a relatively new class of two-dimensional transition metal carbides, nitrides and carbonitrides experiencing increasing attention for tribological applications. Due to their multi-layer structure with relatively weak inter-layer bonding, a self-lubricating character is enabled. A possible, but not yet explored, application of MXenes is the addition to UHMWPE with the aim to improve the biotribological behavior of tibial inlays of total knee arthroplasties (TKA). Within this study, Ti3C2Tx-UHMWPE-composites with 0.5 wt.‑%, 1.0 wt.‑% and 2.0 wt.‑% MXenes were biotribologically tested using a pin-on-disk tribometer in oscillating sliding mode lubricated with diluted bovine calf serum at 37 °C. Thereby, a reduction of the coefficient of friction by up to 22 % compared to pure UHMWPE was demonstrated and the determined wear rates of the disks decreased considerably by 25 % (0.5 wt.‑% and 1.0 wt.‑%) and 43 % (2.0 wt.‑%). Furthermore, the composite-disks reduced the wear rates of the tested Co28Cr6Mo-pins by up to 19 %. Both the reduction of friction and wear show the great potential of MXenes as a reinforcement phase to UHMWPE to improve the biotribological behavior of tibial inlays and thus, increase the service life of TKA in the long-ter

Biotribological behavior of ta-C coatings for load-bearing implants - Rothammer, Benedict; Bartz, Marcel; Wartzack, Sandro; Weihnacht, Volker; Marian, Max (4th International Brazilian Conference on Tribology – TriBoBR 2023, 2023)
1. Introduction Amorphous/diamond-like carbon (DLC) coatings deposited on the articulating surfaces of total hip (THR) or total knee replacements (TKR) have the potential to enhance the overall biotribological behavior and longevity [1-2]. This requires excellent adhesion to soft and hard implant materials, biocompatibility as well as superior mechanical properties and wear resistance [3]. 2. Materials and Methods Medical grade Co28Cr6Mo (CoCr), Ti6Al4V (Ti64) and ultrahigh molecular weight polyethylene (UHMWPE) were studied as substrate materials. Tetrahedral amorphous carbon (ta-C) coatings were deposited by plasma-filtered pulsed laser-arc technique using a commercial PVD coating system. The surface topography, cytocompatibility as well as mechanical properties and adhesion of ta-C coatings were analyzed. The biotribological behavior was studied in pin-on-disk sliding experiments under substitute synovial fluid lubrication. The wear behavior was investigated through laser scanning microscopy (LSM), Raman spectroscopy as well as focused ion beam scanning electron microscopy (FIB-SEM). [4] 3. Results and discussion The ta-C coatings exhibited typical morphology and composition and featured higher roughness compared to the substrates. Contact angle measurement as well as indirect and direct cell testing suggested sufficient biocompatibility and suitability for biomedical applications. The ta-C coatings demonstrated excellent mechanical properties with improved hardness- to-elasticity ratio. The adhesion between the coatings and CoCr, Ti64, and UHMWPE substrates was excellent. Despite higher friction, the ta-C coatings significantly reduced wear on both contacting bodies. The intact coating effectively protected the UHMWPE disk from adhesive or abrasive wear. However, crack networks and near-surface fatigue were observed after prolonged testing. Particle analysis revealed minimal release of nanometer-sized particles compared to the reference groups. The biotribological behavior remained consistent over time. [4] Cracking and folding in the ta-C coating on UHMWPE substrates were attributed to the mismatch in thermal expansion coefficients between the coating and substrate materials, which led to varied expansion and shrinkage during temperature changes, along with the high intrinsic compressive stress typical of ta-C coatings. The compressive stress in the coating, combined with time-dependent plastic deformation of the PE substrate, resulted in fold formation, coating shearing, crack formation, and subduction. Furthermore, cyclic tribological stress exceeded the compressive stress resistance of the ta-C coating, leading to the formation and propagation of microcracks near the surface (near-surface fatigue). Anyways, the durability of the ta-C coating is expected to extend the service life of metallic and polymeric implant materials. [4] 4. References [1] B. Rothammer et al.: Amorphous Carbon Coatings for Total Knee Replacements—Part II: Tribological Behavior, Polymers, 13, 2021, 1880, DOI: 10.3390/polym13111880 [2] B. Rothammer, K. Neusser, M. Bartz, S. Wartzack, A. Schubert, M. Marian: Evaluation of the Wear-Resistance of DLC-Coated Hard-on-Soft Pairings for Biomedical Applications, Wear, 523, 2023, 204728, DOI: 10.1016/j.wear.2023.204728 [3] R. Shah et al.: Enhancing mechanical and biomedical properties of protheses - Surface and material design, Surfaces and Interfaces, 27, 2021, 101498, DOI: 10.1016/j.surfin.2021.101498 [4] B. Rothammer et al.: Wear mechanism of superhard tetrahedral amorphous carbon (ta-C) coatings for biomedical applications, Advanced Materials Interfaces, 2023, 2202370, DOI: 10.1002/admi.202202370

Biotribological investigation of amorphous carbon coatings in hard-on-soft contact for biomedical applications - Rothammer, Benedict; Neusser, Kevin; Bartz, Marcel; Wartzack, Sandro; Marian, Max (DKOU 2024, 2024)
Objectives: Amorphous carbon (DLC) coatings deposited on the articulating surfaces of total joint replacements (TJRs) have the potential to enhance the biotribological behavior and longevity [1]. Therefore, we employ an ultrahigh molecular weight polyethylene (PE) ball-on-three titanium (Ti) alloy pin configuration lubricated by simulated body fluid to effectively carry out screening tests. Thus, the influence of the choice of the coated component (Ti and/or PE) were studied. Furthermore, coatings deposited either on the metallic or on both contacting partners (metal/metal or polymer/metal) have been studied in literature so far [2], [3]. Yet, there is a lack of fundamental investigations on the influence of the choice of the coated component. Moreover, non-sterilized PE has mostly been considered in the literature as polymeric substrate and the transfer to coating HXLPE, which is expected to predominate in the future, has been insufficiently examined. Methods: Within this contribution, the influence of aforementioned variations in the configurations are addressed by means of two different DLC coatings applied to polymeric (HXLPE and PE) and/or Ti substrates in a higher stressed and a more moderate load case under peri-implant boundary conditions. The wear rates were determined using laser scanning microscopy. Also, the materials, coating characterization, and biotribological testing are presented and discussed in the light of the corresponding results. Results and conclusion: The DLC coatings featured excellent mechanical properties with a substantial enhancement of indentation hardness and modulus. The adhesion of the coatings as determined in modified scratch tests was considered as very good to PE and as still good to Ti, thus confirming the potential for the use in TJRs. Although the coatings predominantly lead to an increase in friction due to the considerably higher roughness, wear was substantially reduced. Due to higher hardness and good adhesion, this applied to DLC-coated PE against DLC-coated Ti, with up to 80% reduction in ball wear and up to 99% reduction in pin wear compared to uncoated references. While only the metallic components were mostly coated in studies reported in literature, our study showed that coating the PE component in particular is of decisive importance for enhancing the wear performance and increasing the service life of TJRs. Moreover, single sided coating resulted in higher wear of the uncoated counterpart. In the future, this should be considered when assessing coatings for biomedical hard/soft pairings and, in particular, coatings deposited on both articulating surfaces, polymeric and metallic, should be pursued and further optimized. References 1. Skjöldebrand C, Tipper JL, Hatto P, Bryant M, Hall RM, Persson C. Current status and future potential of wear-resistant coatings and articulating surfaces for hip and knee implants. Mater Today Bio. 2022 Apr 30;15:100270. DOI: 10.1016/j.mtbio.2022.100270 2. Rothammer B, Neusser K, Marian M, Bartz M, Krauß S, Böhm T, Thiele S, Merle B, Detsch R, Wartzack S. Amorphous Carbon Coatings for Total Knee Replacements-Part I: Deposition, Cytocompatibility, Chemical and Mechanical Properties. Polymers (Basel). 2021 Jun 11;13(12):1952. DOI: 10.3390/polym13121952 3. Rothammer B, Marian M, Neusser K, Bartz M, Böhm T, Krauß S, Schroeder S, Uhler M, Thiele S, Merle B, Kretzer JP, Wartzack S. Amorphous Carbon Coatings for Total Knee Replacements-Part II: Tribological Behavior. Polymers (Basel). 2021 Jun 5;13(11):1880. DOI: 10.3390/polym13111880

Biotribological screening of amorphous carbon coatings on hard-on-soft pairings for total knee arthroplasty - Neusser, Kevin; Rothammer, Benedict; Bartz, Marcel; Wartzack, Sandro; Marian, Max (63. Tribologie-Fachtagung. Reibung, Schmierung und Verschleiß. Forschung und praktische Anwendungen., 2022)
This screening reveals the applicability and biotribological effectiveness of amorphous carbon coating systems developed for hard-on-soft pairings in biomedical applications, such as total knee replacements, to potentially reduce implant wear and thus to prevent premature failure and extend the service lif

Biotribological screening of amorphous carbon coatings on hard-on-soft pairings for total knee arthroplasty - Neusser, Kevin; Rothammer, Benedict; Marian, Max; Bartz, Marcel; Wartzack, Sandro (5th YOUNG TRIBOLOGICAL RESEARCHER SYMPOSIUM, 2022)
The purpose of endoprosthetic joint replacement is to regain the functionality and allow patients to live a more mobile and pain-free life. Aseptic loosening of total knee arthroplasty (TKA) is a major cause of premature failure, with wear particles removed from the implant materials being largely responsible. Therefore, great efforts are being made to reduce the wear of polymer inlays by surface modifications. This study concentrates on the screening of the effectiveness of wear-reducing amorphous carbon coating systems on hard-on-soft pairings (metal-on-polymer). The biotribological behavior of the uncoated and coated pairings is investigated using a climate- and stress-controlled rheometer supplemented with a tribo-cell in a polyethylene ball and three metallic pins configuration, lubricated with diluted bovine calf serum (BCS) at 37 °C, in oscillatory sliding mode. The frictional behavior is analyzed in-situ while the wear performance is characterized ex-situ using light microscopy and laser scanning microscopy. This screening reveals the applicability of amorphous carbon coatings to the considered materials used for biomedical applications. It demonstrates the potential for wear reduction and forms a basis to determine the most promising of the deposited diamond-like carbon (DLC) coatings, therefore allowing for more focused research in the development of tribologically effective coating system

Bridging the sim2real gap. Investigating deviations between experimental motion measurements and musculoskeletal simulation results—a systematic review - Wechsler, Iris; Wolf, Alexander; Shanbhag, Julian; Leyendecker, Sigrid; Eskofier, Björn; Koelewijn, Anne; Wartzack, Sandro; Miehling, Jörg (Frontiers in Bioengineering and Biotechnology, 2024)

CAD-based Tolerance Analysis in Preliminary Design Stages Enabling Early Tolerance Evaluation - Götz, Stefan; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the ASME IMECE 2018, 2018)
Associated with manufacturing and assembly processes, inevitable geometric deviations have a decisive influence on the function and quality of products. Therefore, their consideration and management are important tasks in product development. Moreover, to meet the demand for short development times, the front-loading of design processes is indispensable. This requires early tolerance analyses evaluating the effect of deviations in a design stage, where the product’s geometry has not yet been finally defined. Since such an early tolerance consideration allows quick and economic design changes seeking for robust designs, it is advisable that the design engineer, who is entirely familiar with the design, should take this step. For this purpose, this paper presents an easy-to-use CAD-based tolerance analysis method for skeleton models. The relevant part deviations are represented by varying geometric dimensions with externally driven family tables. The approach comprises the strength of vector-based methods but does not require an expensive set-up of tolerance analysis models. Particularly, the novelty of this method lies in the CAD-internal sampling-based tolerance analysis of simple geometries without the use of expensive CAT software. This enables designers to evaluate the effect of tolerances already at the preliminary design stage. Using a case study, the presented approach is compared with the conventional vector-based tolerance analysis. <br
Keywords: CAD-based tolerance analysis; early tolerance management; skeleton model

CAD-Gestaltmodellierung in VR für die frühe Entwurfsphase - Fechter, Marius; Schleich, Benjamin; Wartzack, Sandro (Konstruktion, 2020)
Virtual Reality bietet neben der stereoskopischen Visualisierung zusätzlich die Möglichkeit der natürlichen Interaktion mit virtuellen Objekten ähnlich der Interaktion mit physischen Objekten in der Realität. Der nachfolgende Beitrag beschreibt eine auf Fingertracking basierende Methode, mit der die Gestalt eines frühen Entwurfs innerhalb einer virtuellen Umgebung in einer CAD-Anwendung synthetisiert werden kann.

Cascading Forgetting in Product Development - Challenges and Evaluation - Kügler, Patricia; Schon, Claudia; Schleich, Benjamin; Staab, Steffen; Wartzack, Sandro (Proceedings of the 22nd International Conference on Engineering Design (ICED19), 2019)
Vast amounts of information and knowledge is produced and stored within product design projects. Especially for reuse and adaptation there exists no suitable method for product designers to handle this information overload. Due to this, the selection of relevant information in a specific development situation is time-consuming and inefficient. To tackle this issue, the novel approach Intentional Forgetting (IF) is applied for product design, which aims to support reuse and adaptation by reducing the vast amount of information to the relevant. Within this contribution an IF-operator called Cascading Forgetting is introduced and evaluated, which was implemented for forgetting related information elements in ontology knowledge bases. For the evaluation the development process of a test-rig for studying friction and wear behaviour of the cam/tappet contact in combustion engines is analysed. Due to the interdisciplinary task of the evaluation and the characteristics of semantic model, challenges are discussed. In conclusion, the focus of the evaluation is to consider how reliable the Cascading Forgetting works and how intuitive ontology-based representations appear to engineer
Keywords: Intentional Forgetting; Ontologies; Knowledge management; Semantic data processing

Case-Based-Reasoning zur Vorhersage von Produkteigenschaften - Gerschütz, Benjamin; Götz, Stefan; Hörmann, Matthias; Wartzack, Sandro (Artificial Intelligence und Machine Learning in der CAE-basierten Simulation, 2023)

CAx für Ingenieure - Eine praxisbezogene Einführung - Vajna, Sándor; Weber, Christian; Zeman, Klaus; Hehenberger, Peter; Gerhard, Detlef; Wartzack, Sandro (Springer Vieweg, 2018)
Dieses nun in der dritten Auflage erschienene Buch vermittelt die Grundlagen des systematischen Einsatzes von rechnerunterstützten Methoden, Vorgehensweisen und Werkzeugen in der Produktentstehung. Es bietet seinen Zielgruppen in knapper und übersichtlicher Form das Rüstzeug für die erfolgreiche Anwendung von CAx-Systemen. Vorgehensweisen und Beispiele basieren auf Erfahrungen in Industrie und Hochschulpraxis, wo sie ihre Effizienz bewiesen haben. Die 3. Auflage wurde gründlich überarbeitet, der Kreis der Autoren erweitert. So kamen nicht nur Aspekte unterschiedlicher Modellierungsarten, Mechatronik und Wissensverarbeitung hinzu, sondern auch Ausführungen zu Systembegriff und Modellaufbau (diese bilden die Basis für CAx-Anwendungen). Sie alle beeinflussen immer stärker die Fertigungstechnik und den modernen Fahrzeug-, Maschinen- und Anlagenbau und sie spannen den Bogen zur Systemtechnik. Neben dem aktuellen und zukünftigen Leistungsstand von CAx-Systemen wurden auch Richtlinien und Empfehlungen zum Stand der Technik berücksichtig
Keywords: Anlagenbau; Fertigung; Industrie; Ingenieur; Ingenieurwissenschaften; Lineare Optimierung; Maschine; Modellbildung; Planung; Praxis

Challenges and Potentials of Digital Twins and Industry 4.0 in Product Design and Production for High Performance Products - Wagner, Raphael; Schleich, Benjamin; Haefner, Benjamin; Kuhnle, Andreas; Wartzack, Sandro; Lanza, Gisela (Procedia CIRP Volume 84, 2019)
Digital twins offer great opportunities in various domains of the product engineering process. However, current approaches to the use of digital twins only focus on different separated disciplines. In contrast to that, it is expected that the holistic use of digital twin models in product development and production will dominate future product generations, because they allow to create high-performance products competitively. This paper explores important challenges and future potentials of digital twins and Industry 4.0 for the seamless integration of product specification and production. In this regard, approaches of linking digital twins to other domains open up new possibilities in tolerance allocation and production integration. Thereby, the most efficient product specifications in technical and economic terms are achieved for the manufacturer. In addition, the connectivity of Industry 4.0 broadens the scope and enables the evaluation of alternative approaches in production planning and control. Approaches at the organizational level, product functions with specifications beyond the technological limits and production control strategies (e.g. order dispatching) ensure high performance operations. Simulations with a digital production twin with integrated digital product twin allow early estimations even before the actual ramp-up of the product. The future challenge addressed in this paper is to define a consistent framework for the holistic use of digital twins in the entire product development process, which requires the integration of product designers and production planner concept
Keywords: Product development; Production planning; Information

Challenges in interaction modelling with digital human models – A systematic literature review of interaction modelling approaches - Wolf, Alexander; Miehling, Jörg; Wartzack, Sandro (Ergonomics, 2020)
Digital human models (DHM) allow for a proactive ergonomic assessment of products by applying different models describing the user-product interaction. In engineering design, DHM tools are currently not established as computer-aided ergonomics tools, since (among other reasons) the interaction models are either cumbersome to use, unstandardised, time-demanding or not trustworthy. To understand the challenges in interaction modelling, we conducted a systematic literature review with the aim of identification, classification and examination of existing interaction models. A schematic user–product interaction model for DHM is proposed, abstracting existing models and unifying the corresponding terminology. Additionally, nine general approaches to proactive interaction modelling were identified by classifying the reviewed interaction models. The approaches are discussed regarding their scope, limitations, strength and weaknesses. Ultimately, the literature review revealed that prevalent interaction models cannot be considered unconditionally suitable for engineering design since none of them offer a satisfactory combination of genuine proactivity and universal validity
Keywords: Computer-aided ergonomics; digital human models; interaction modelling; engineering design; posture and movement prediction

Challenges in the Design of Products for Elderly People - Paetzold, Kristin; Wartzack, Sandro; Miehling, Jörg (Proceedings of the 9th Workshop on Integrated Product Development, 2013)
In recent years, there were significant changes in our society related to age structures and this will have an appreciable effect in the coming years. This demographic change is accompanied by an aging society, a challenge for all areas of our life. The engineering sciences can offer solutions, which support less for fundamental change in the situation, but certainly can mitigate the effects of these changes on the society. Using technical systems, we are able to preserve the quality of life, so that e.g. life in a familiar home environment is possible without additional support even in old age. The development of technological systems for this group of users is challenging as the elderly not only have very complex but also very individual requirements for products. This is due to their life experiences, socialisation as well as their age-and disease-related restrictions. Challenges that arise for product development are presented in this paper. Furthermore the benefits and ongoing research of utilising computer technology to support the development of products for elderly people are outlined. To stay competitive these days the virtual product development is continually promoted but in the context of products for seniors especially the virtual assessment of user-product interfaces has the potential to reveal, analyse and optimise cause-effect relationships, possibly not observable neglecting these emerging digital technologies.
Keywords: Design for Elderly; User-Centred Design Methods; Digital Human Modelling; Biomechanics; Virtual Product Development

Challenges in the Virtual Geometry Assurance of Proton Exchange Membrane Fuel Cell Stacks - Roth, Martin; Bickel, Sebastian; Götz, Stefan; Wartzack, Sandro (Procedia CIRP, 2024)
Hydrogen-powered fuel cells will play a vital role in the next generation of energy systems. In this regard, Proton Exchange Membrane Fuel Cells (PEMFC) represent a promising technical solution for all applications where direct electrification is not technically feasible or economically viable, such as the propulsion of heavy vehicles. However, robust production of high-quality fuel cell systems in scalable series production can only be achieved by an early assurance of the product quality considering the numerous variations on geometry element, part, and assembly level. This article presents the challenges and outlines the vision of a geometry assurance process capable of simulating the probabilistic assembly behavior of PEMFC stacks by multi-physics variation simulation, e.g., considering aspects of Finite Element Analysis and Computational Fluid Dynamics, under a realistic representation of the part manufacturing and assembly processes and their operation under variations. The findings reveal future research directions fostering the series production of robust, high-quality PEMFC stacks.
CRIS-Team Scopus Importer:2024-11-29
Keywords: Geometry Assurance; Multi-physics Simulation; Proton Exchange Membrane Fuel Cell; Tolerancing

Challenges of Geometrical Variations Modelling in Virtual Product Realization - Schleich, Benjamin; Wartzack, Sandro (Procedia CIRP, Volume 60, 2017)
Geometrical variations are inevitably introduced during manufacturing and can thus be observed on every manufactured artefact. Although it is widely acknowledged that these part deviations distinctly affect the function and quality of mechanical assemblies, the majority of virtual product validation activities still rely on the modelling and analysis of the nominal product geometry without considering such geometrical part deviations. In order to overcome this shortcoming, the aim of this paper is to highlight the current status of geometrical variations modelling approaches for virtual product realization and to carve out future challenges in this domain. For this purpose, different geometry representation schemes, which are nowadays used during virtual product realization, are discussed. Furthermore, they are linked to the various virtual product realization activities and potentials for improvements for their use and exchange are highlighted. The novelty of the contribution can be found in the comprehensive review of approaches for geometrical variations modelling, their placement into a changing virtual product development landscape, and the exposition of elaborated challenges for future research in this domain.
Keywords: Geometrical Variations Management; Geometric Modelling; Skin Model Shapes

Characterization of a fast gas analyzer based on Raman scattering for the analysis of synthesis gas - Eichmann, Simone; Weschta, Martin; Kiefer, Johannes; Seeger, Thomas; Leipertz, Alfred (Review of Scientific Instruments, 2010)
A sensor system for fast analysis of synthesis gas (mixtures of CO and H2) is proposed and characterized. The system is based on spontaneous Raman scattering, which enables simultaneous concentration measurements of all relevant species. For typical synthesis gas applications, this system has to face large variations of temperature and pressure. In addition, strong fluctuations in mixture composition may occur, which lead to rather inconvenient signal intensities. In this paper, we describe a low resolution spectrometer designed to function as a synthesis gas sensor and characterize pressure and temperature effects on concentration measurements. In addition, the use of different spectral ranges and calibration strategies is investigated in view of measurement accuracy and precision. © 2010 American Institute of Physics.
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