Materialparameter-Optimierung für die Crashberechnung in frühen Entwicklungsphasen - Gruber, Georg; Klein, Daniel; Wartzack, Sandro (NAFEMS 2012, 2012)
Durch die drastische Verknappung der Ressourcen und den damit verbundenen Restriktionen seitens der Politik (z.B. CO2-Grenzwerte) hat speziell in der Automobilindustrie der Leichtbau enorm an Bedeutung gewonnen. Um Leichtbaustrategien möglichst effizient durchführen zu können, ist es erforderlich bereits die frühe Entwicklungsphase auszunutzen, da hier noch die maximale Designfreiheit zur Berücksichtigung aller Anforderungen vorliegt. Doch gerade die Berechnung und Auslegung in Bezug auf die Crashsicherheit von Bauteilen aus Verbundwerkstoffen ist aufgrund der komplexen mechanischen Eigenschaften und der fertigungsbedingten Anisotropie bisher noch sehr schwierig und zeitaufwändig. Deshalb wurde ein Ansatz entwickelt, der es ermöglicht eine Materialbeschreibung für die Crashberechnung in frühen Entwicklungsphasen zu generieren. Über die Funktion *PART_COMPOSITE werden in LS-DYNA® für ein einziges Bauteil mehrere bereits bestehende Materialmodelle definiert. Dabei enthalten diese Materialmodelle Parameter, die so aufeinander abgestimmt werden können, dass sich in Summe das gewünschte Materialverhalten einstellen lässt. Die Identifikation dieser Materialparameter wird durch den Einsatz der Optimierungssoftware LS-OPT® entscheidend beschleunigt. Damit kann innerhalb kürzester Zeit ein valides Materialmodell erzeugt werden, das den Anforderungen in frühen Entwicklungsphasen gerecht wird. Das genaue Vorgehen wird im Folgenden am Beispiel eines kurzfaserverstärkten Thermoplasten gezeigt.
Keywords: Simlution; Crash; Composites

MBSE along the Value Chain – An Approach for the Compensation of additional Effort - Wilking, Fabian; Schleich, Benjamin; Wartzack, Sandro (2020 IEEE 15th International Conference of System of Systems Engineering (SoSE), 2020)
Keywords: Proceedings of the 2020 IEEE 15th International Conference of System of Systems Engineering (SoSE)

Medium-Level Architectures for Digital Twins: Bridging Conceptual Reference Architectures to Practical Implementation in Cloud, Edge and Cloud–Edge Deployments - Fett, Michel; Kraft, Marcel; Wilking, Fabian; Götz, Stefan; Wartzack, Sandro; Kirchner, Eckhard (Electronics, 2024)
The integration of Digital Twins (DTs) is becoming increasingly important in various industries. This entails the need for a comprehensive and practical IT infrastructure framework. This paper presents a modifiable medium-level architecture that serves as a link between established reference architectures such as RAMI 4.0 and the pragmatic implementation of Digital Twins. The functionalities of an IT infrastructure are considered, and functional hardware and software components for fulfilling these are described. The proposed architecture is suitable for various deployment scenarios, including local, cloud and hybrid cloud–edge configurations. In order to improve the applicability of the medium-level architecture, a step-by-step procedure is also proposed, which helps to transfer the overarching requirements for a Digital Twin into a suitable IT infrastructure. Finally, the results are demonstrated by an exemplary application to a two-stage industrial gearbox.<br
Keywords: digital twin; cyber–physical system; RAMI 4.0; architecture; IT infrastructure

Meta-model based generation of solution spaces in sheet-bulk metal forming - Sauer, Christopher; Schleich, Benjamin; Wartzack, Sandro (Procedia CIRP, 2020)
Sheet-bulk metal forming (SBMF) is an emerging manufacturing technology that offers vast potential for lightweight design and functional integration. However, product designers often lack information about the required manufacturing parameters for their specific design. This problem is currently tackled by a knowledge acquisition process from manufacturing experts in combination with meta-modelling techniques. These meta-models predict resulting manufacturing parameters for given part design properties. When employing this design-for-manufacturing approach, it is key for product designers to evaluate many design alternatives that are all manufacturable with given forming machines. This is currently done by a genetic algorithm-based optimization of the meta-models with regard to manufacturing features. This papers proposes a novel approach for generating many design alternatives based on the meta-models and gathering them in a solution space. In doing so it is possible to review all manufacturable sheet-bulk metal forming part variants and let the product designers decide which part design fits best. The approach is applied to a locking teeth part, which highlights the usability of the new method.<br
Keywords: Meta-Modelling; Multi-objective optimization; Knowledge acquisition; Genetic algorithms

Metamodelle in der Anwendung: Abbildung von Fertigungseinflüssen auf die geometrische Genauigkeit additiv gefertigter Bauteile - Kelber, Vincent; Schächtl, Paul (Summer School Toleranzmanagement - Beiträge zur 4. Summer School - September 2020, 2020)

Metaproperty-guided Deletion from the Instance-Level of a Knowledge Base - Schon, Claudia; Staab, Steffen; Kügler, Patricia; Kestel, Philipp; Schleich, Benjamin; Wartzack, Sandro (Knowledge Engineering and Knowledge Management - 21st International Conference, 2018)
The ontology modeling practice of engineering metaproperties of concepts is a well-known technique. Some metaproperties of concepts describe the dynamics of concept instances, i.e. how instances can and cannot be altered. We investigate how deletions in an ontology-based knowledge base interact with the metaproperties rigidity and dependence. A particularly useful effect are delete cascades. We evaluate how rigidity and dependence may guide delete cascades in an engineering application. A case study in the area of product development shows that beyond explicitly defined deletions, our approach achieves further automated and desirable deletions of facts with high precision and good recall.

Methoden der Entscheidungsfindung - Luft, Thomas; Le Cardinal, Julie; Wartzack, Sandro (Handbuch Produktentwicklung, 2016)
Die steigende Dynamik und Komplexität im Unternehmensumfeld sowie ein zunehmender Kostendruck erschweren die Entscheidungsfindung im Rahmen der Produktentwicklung. Um seine Wettbewerbsfähigkeit zu sichern, muss jedes Industrieunternehmen wesentliche Ziele erfüllen: Diese sind vor allem die Erfüllung der Kundenzufriedenheit, der Profitabilität des Unternehmens und die Motivation seiner Mitarbeiter. Jedes Unternehmen versucht diese Ziele durch das Treffen entsprechender Entscheidungen zu erreichen. Der Begriff der „Entscheidung“ beziehungsweise „Entscheidungsfindung“ ist weder in der Literatur noch in der Praxis einheitlich definiert. Daher wird dieser Begriff in der Wissenscha" unterschiedlich interpretiert: Die Entscheidungstheorie wird von einigen Autoren im Allgemeinen als empirische und logische Analyse rationalen Entscheidungsverhaltens definiert (Bamberg et al. 2012). Dagegen beschreiben andere Autoren die Entscheidungstheorie als wissenscha"liche Disziplin, die die Aufgabe hat, „Erkenntnisse über das menschliche Entscheidungsverhalten zu gewinnen und diese [. . .] für die Lösung konkreter Entscheidungsprobleme zur Verfügung zu stellen“ (Obermaier & Saliger 2013). Ratio nales Entscheiden besteht darin, „jene Lösungen zu bevorzugen, die ein möglichst hohes Ausmaß an Zielerfüllung erbringen“ (Haberfellner et al. 2012). Dabei entspricht eine Entscheidung im Allgemeinen der Auswahl zwischen Alternativen. Eine verantwortungsvolle und zielorientierte Auswahl impliziert in der Regel die Vorweg nahme des Ergebnisses der Entscheidung, das dieser Auswahl inhärent zugrunde liegt. Nachfolgend verstehen die Autoren unter der Entscheidung beziehungsweise der Entscheidungsfindung den gesamten Ent schei dungs(findungs)prozess (d. h. das gesamte Vorgehen, um zu einer Entscheidung zu gelangen). Aufgrund der uneinheitlichen Interpretation des Entscheidungsbegriffs werden in diesem Buchkapitel nach Darstellung der Spezifika der Entscheidungsfindung in der Produktentwicklung zunächst die theoretischen Grund la gen zu Komplexität, Unsicherheit, Arten, Ebenen, Formen sowie Kriterien einer guten Entscheidungsfindung kurz beschrieben (Kapitel IV-7.2). Darauf aufbauend wird der Entscheidungsfindungsprozess erläutert ( Kapitel IV-7.3). Dieser besteht aus allgemeinen, generischen Schritten, die grundsätzlich für jede Art von Entscheidungsfindung geeignet sind. Abschließend werden einige ausgewählte Methoden zur multikriteriellen Bewertung als Kernelemente des Entscheidungsfindungsprozesses an einem Praxisbeispiel aufgezeigt (Kapitel IV-7.4). Dadurch sollen Entscheider einen Überblick über die Komplexität und Unsicherheit von Entscheidungssituationen, über den Prozess der Entscheidungsfindung sowie über ausgewählte Bewertungsmethoden bekommen.
Keywords: Grundlagen der Entscheidungsfindung; Spezifika der Entscheidungsfindung in der Entwicklung; Komplexität der Entscheidungsfindung; Unsicherheit bei der Entscheidungsfindung; Arten der Entscheidungsfindung; Ebenen der Entscheidungsfindung; Formen der Entscheidungsfindung; Kriterien für eine gute Entscheidung; Prozess der Entscheidungsfindung; Entscheidungsfindungsprozess; Kompetenzmodell; SACADO-Methodik; Bewertungsverfahren als Kernelemente des Entscheidungsprozesses; Einfache Bewertungsmethoden – Die Punktbewertung; Aufwändige Bewertungsmethoden – Die Nutzwertanalyse; Komplexe Bewertungsmethoden – der Analytische Hierarchieprozess; Komplexe Bewertungsmethoden – Überblick über die ELECTRE- und PROMETHEE-Methode

Methoden der Produktentwicklung - ein subjektiver Vergleich von Theorie und Praxis - Wartzack, Sandro (18. Symposium Design for X, 2005)
UnivIS-Import:2015-04-16:Pub.2005.tech.FT.FT-KLMEFK.method

Methodengestützte Referenzvorgehensweise für neue Umformverfahren - Weckenmann, Albert; Reithmeier, Eduard; Merklein, Marion; Behrens, B.-A.; Wartzack, Sandro; Kästner, M.; Akkasoglu, Gökhan; Ohrt, Christoph; Schneider, Thomas; Salfeld, V.; et al. (Zeitschrift für wirtschaftlichen Fabrikbetrieb, 2012)
LFT Import::2019-07-29 (1782)

Methoden zur Reduzierung und Berücksichtigung der Unsicherheiten von dimensionellen Messgrößen in der Toleranzanalyse - Müller, Andreas; Heling, Björn; Schleich, Benjamin; Oberleiter, Thomas; Willner, Kai; Wartzack, Sandro; Hausotte, Tino (Industriekolloquium der Forschergruppe FOR 2271, 2019)

Methode zur Berücksichtigung geometrischer Abweichungen bei der Auslegung von Zylinderrollenlagern - Atalay, Onur; Koch, Oliver; Kramer, Vincent; Bartz, Marcel; Götz, Stefan; Wartzack, Sandro; Schleich, Benjamin (15. VDI-Fachtagung Gleit- und Wälzlagerungen 2023: Gestaltung – Berechnung – Einsatz, 2023)
Wälzlager sind im Maschinenbau aufgrund ihrer präzisen und reibungsarmen Führung rotierender Bauelemente bei gleichzeitig geringen Kosten von großer Bedeutung. In der Regel werden bei der Auslegung von Wälzlagerungen ideale Geometrien von Lagern und Anschlusskonstruktion zugrunde gelegt. Reale Bauteile weichen jedoch unvermeidlich von ihrer nominalen Gestalt ab, was zu Veränderungen der lagerinternen Kontakt- und Lastverhältnisse führt und somit das Betriebsverhalten des Lagers z. B. hinsichtlich Lebensdauer, Reibmoment und Schwingungsverhalten beeinträchtigen kann. Durch Berücksichtigung dieser Effekte bei der Auslegung von Wälzlagerungen können potentielle Probleme im Betrieb bereits in der Entwicklungsphase erkannt und entsprechende Abhilfemaßnahmen, z. B. durch Anpassung der Bauteiltoleranzen ergriffen werden. Somit kann eine Verbesserung der Produktqualität erzielt werden. Dieser Beitrag stellt daher eine Methode zur Integration von abweichungsbehafteten Bauteilgeometrien bei der Berechnung von Zylinderrollenlagerungen vor.
Keywords: Wälzlager; Toleranzanalyse; Maschinenelemente

Methode zur Einbindung von heuristischem Wissen in die erweiterte matrixbasierte Produktbeschreibung - Tüchsen, Johann; Obendorfer, Moritz; Luft, Thomas; Schleich, Benjamin; Wartzack, Sandro (Tagungsband 16. Gemeinsames Kolloquium Konstruktionstechnik, 2018)
Im Zuge der zunehmenden Vernetzung und Digitalisierung ist es zur Beherrschung von Komplexität im Rahmen der interdisziplinären und kollaborativen Produktentwicklung notwendig, die vielfältigen Abhängigkeiten zwischen Produktmerkmalen und Produkteigenschaften detailliert zu beschreiben. Die vorliegende Arbeit stellt daher eine Methode zur Implementierung und Verarbeitung von heuristischem, impliziten Wissen in der erweiterten matrixbasierten Produktentwicklung (eMBPB) und im Characteristic-Property-Model (CPM) vor. Mittels dieser Methode können das Erfahrungswissen der Entwickler in den holistischen Produktbeschreibungsansatz integriert und Produkte unter der Berücksichtigung von Prozesseinflüssen und Unsicherheiten beschrieben werden. Diese vorgeschlagene Methode wird zudem anhand des industriellen Beispiels der Welle-Rotorblechpaket-Verbindung veranschaulicht und evaluiert.
Keywords: Wissensmanagement; heuristisches Wissen; eMBPB; CPM

Methode zur Parameteroptimierung komplexer Mechanismen hinsichtlich kinematischer Anfor-derungen - Heling, Björn; Wartzack, Sandro (Design for X - Beiträge zum 27. DfX-Symposium, 2016)
Shorter product life cycles along with continuously changing requirements lead to a demand for more efficient product development processes. Result-ing from these upcoming challenges the guiding principle „Right-First-Time“ focuses on a reduction of iteration loops during product development. As a consequence product developers need suitable tools and methods to allow a more efficient product development process. In this contribution a new meth-od, which is based on methods for the conceptions of systems in motion and Robust-Design principles, is presented. This novel combination takes kinemat-ic requirements as well as possible geometric uncertainties into account. As a consequence the designed system not only fulfills the kinematic requirements but is also insensitive to deviations from the ideal state.
Keywords: Robust Design; Parameter Optimization; Taguchi Method; kinematic design

Method for calculating the contact between roller end face and ring rib of roller bearinx in multi-body simulations - Wirsching, Sven; Bohnert, Christof; Tremmel, Stephan; Wartzack, Sandro (STLE 2019 - 74th Annual Meeting and Exhibition of the Society of Tribologists and Lubrication Engineers, 2019)
To summarize, the PinP method provides similarly accurate results as the theory of HERTZ. But in addition, the PinP method can be used to describe more complex geometries that generate curved ellipses as contact zones. These can only be described simplified by HERTZ. Instead, contact situations of two contact zones are not. This is the great benefit of the PinP method, which is suitable for such constellations. In a further step, this has to be examined more precisely. For this purpose, higher numerical methods, such as FEM, will be used for a comparison.
CRIS-Team Scopus Importer:2019-10-22
Keywords: Computation: Dynamic Modelling; Contacts: Contact Mechanics; Rolling Bearings: Tapered Roller Bearings

Method for the consideration of statistically distributed geometrical deviations in the design of cylindrical roller bearing arrangements - Kramer, Vincent; Atalay, Onur; Rüth, Lukas; Wingertszahn, Patrick; Bartz, Marcel; Götz, Stefan; Schleich, Benjamin; Koch, Oliver; Wartzack, Sandro (Forschung Im Ingenieurwesen-Engineering Research, 2024)
Rolling bearings are of great importance in all areas of mechanical engineering due to their precise and low-friction guidance of rotating components at low cost. The design of rolling bearing arrangements is usually based on approximately ideal geometries of bearings and adjacent parts on which the bearing seats are located. However, real components inevitably show statistically distributed deviations from their nominal shapes, which are limited by tolerances. Tight tolerances result in high manufacturing costs while on the other hand their expansion leads to an increase of occurring geometrical deviations which cause changes in the bearing-internal contact and load conditions and can thus impair the operating behavior of the bearing, e.g. with regard to fatigue life, frictional torque or vibration behavior. By taking these effects into account in the design stage, potential problems in operation can be identified early during development and countermeasures can be taken, e.g. by adjusting bearing and seat tolerances. This enables an improvement of overall product quality and a reduction of costs. This paper presents a method for the integration of component deviations in the computation of the fatigue life (Lnmr) and dynamic behavior of cylindrical roller bearing arrangements—both of which are crucial design criteria—based on a combination of statistical tolerance analysis and multi-body simulations. The method is applied to an exemplary use case for illustration.
Created from Fastlane, Scopus look-up

Method for Using IMU-Based Experimental Motion Data in BVH Format for Musculoskeletal Simulations via OpenSim - Wechsler, Iris; Wolf, Alexander; Fleischmann, Sophie; Waibel, Julian; Molz, Carla; Scherb, David; Shanbhag, Julian; Franz, Michael; Wartzack, Sandro; Miehling, Jörg (Sensors, 2023)
Biomechanical simulation allows for in silico estimations of biomechanical parameters such as muscle, joint and ligament forces. Experimental kinematic measurements are a prerequisite for musculoskeletal simulations using the inverse kinematics approach. Marker-based optical motion capture systems are frequently used to collect this motion data. As an alternative, IMU-based motion capture systems can be used. These systems allow flexible motion collection without nearly any restriction regarding the environment. However, one limitation with these systems is that there is no universal way to transfer IMU data from arbitrary full-body IMU measurement systems into musculoskeletal simulation software such as OpenSim. Thus, the objective of this study was to enable the transfer of collected motion data, stored as a BVH file, to OpenSim 4.4 to visualize and analyse the motion using musculoskeletal models. By using the concept of virtual markers, the motion saved in the BVH file is transferred to a musculoskeletal model. An experimental study with three participants was conducted to verify our method’s performance. Results show that the present method is capable of (1) transferring body dimensions saved in the BVH file to a generic musculoskeletal model and (2) correctly transferring the motion data saved in the BVH file to a musculoskeletal model in OpenSim 4.4.<br
Keywords: biomechanics; musculoskeletal modelling and simulation; inertial sensors; motion tracking; data transfer

Methodical approach for the design and dimensioning of mechanical clinched assemblies - Zirngibl, Christoph; Martin, Sven; Steinfelder, Christian; Schleich, Benjamin; Tröster, Thomas; Brosius, Alexander; Wartzack, Sandro (Materials Research Proceedings, 2023)

Methodik zur Validierung, Verifikation und Auswahl mathematischer Metamodelle im Rahmen der virtuellen Produktentwicklung - Sprügel, Tobias; Wartzack, Sandro (Design for X. Beiträge zum 26. DfX-Symposium, 2015)
Product developers need to describe relations between input and output parameters mathematically. This central problem varies in many ways and starts from the description of measurement data and ends with the integration of results from numerical simulations in downstream simulations of similar problems. Therefor meta-models or surrogate models are used. In this publication a methodology for validation, verification and selection of proper meta-models within the virtual product development is presented.
Keywords: meta-model; surrogate model; goodness-of-fit parameter; plausibility-check

Methodische Bestimmung der Systemgrenzen im Produktentwicklungsprozeß - Wartzack, Sandro (Beiträge zum 18. Symposium Design for X, 2007)
UnivIS-Import:2015-04-16:Pub.2007.tech.FT.FT-KLMEFK.method

Methodische Entwicklung mobilitätserhaltender Produkte am Beispiel einer Aufstehhilfe - Krüger, Daniel; Wartzack, Sandro; Eilmus, Sandra; Krause, Dieter; Walter, Johanna; Paetzold, Kristin (Stuttgarter Symposium für Produktentwicklung (SSP) 2013, 2013)
In unserer  Gesellschaft ist  eine Veränderung  der  Altersstruktur zu beobachten, ältere  Menschen machen einen  immer  größeren  Anteil  an  der Gesamtbevölkerung aus. Der Erhaltung von Mobilität im Alter wird zukünftig eine steigende Bedeutung zukommen. Mobilität umfasst neben der Bewegungsfähigkeit auch  den  Transport  von  Dingen,  die  Interaktion  mit  der  Umwelt  oder  die Kommunikation  mit Anderen,  was eine Teilhabe am  gesellschaftlichen  Leben erst ermöglicht. Mobilität ist damit ein wichtiger Aspekt für Lebensqualität. Infolge von Krankheit  oder  natürlichem Altern  sind Menschen von  Einschränkungen der motorischen Fähigkeiten betroffen, die ein selbstständiges  Aufstehen aus sitzender Haltung schwierig machen. Der Beitrag zeigt am Beispiel einer Aufstehhilfe, die der Entlastung des Bewegungsapparates dient und damit teilweise die Wiederherstellung der  Mobilität  ermöglicht, welche  besonderen  Herausforderungen  bei  der Entwicklung von Produkten zu diesem Zweck bestehen. Es wird ein methodisches Framework vorgeschlagen, das Aspekte der Anforderungserhebung, die Simulation von  Mensch-Maschine  Interaktionen  mittels digitaler  Menschmodelle  sowie Methoden des Variantenmanagements bereitstellt.
Keywords: seniorengerechte Produktentwicklung; Nutzerbeschreibung; Variantengestaltung; biomechanische Simulation

Methodische Unterstützungsansätze für die Entwicklung additiv gefertigter Bauteile - Gruber, Georg; Kestel, Philipp; Staab, Andreas; Wartzack, Sandro (Tagungsband der Rapid.Tech 2013 - Fachmesse und Anwendertagung für Rapid-Technologie, 2013)
Additive manufacturing allows the creation of individual and highly innovative products. The reasons are high geometric flexibility and the possibility of including additional functions in the part offered by additive manufacturing. However, the complex dependencies between manufacturing parameters and the resulting properties of the parts are challenging. The present paper deals with special characteristics of additive manufacturing regarding form design and feasibility. Furthermore, state of the art approaches assisting the product developer at the design process are discussed. The focus of the paper is the introduction of a concept of a new process chain, supporting the design process of additive manufactured parts. The goal of the new development process is generating the part’s geometry directly by numerical optimization methods like topology optimization. This is possible thanks to the geometric flexibility offered by additive manufacturing. To be able to consider graded and anisotropic material properties within the optimized structure, an enhanced form of optimization – the so called free material optimization – shall be deployed. The distinct setup of the process chain as well as customized pre and post processing tools allow for a development process which does not involve CAD tools being used to generate the parts geometry.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.method

Methodology for plausibility checking of structural mechanics simulations using Deep Learning on existing simulation data - Sprügel, Tobias; Rothfelder, Richard; Bickel, Sebastian; Grauf, Andreas; Sauer, Christopher; Schleich, Benjamin; Wartzack, Sandro (Proceedings of NordDesign 2018, 2018)
In modern product development, the use of sophisticated simulation tools for assessing the effects of design changes on the intended product behavior is essential. However, setting up valid simulations requires expert knowledge, acquired skills, and sufficient expertise. Design engineers, who perform finite element analysis (FEA) infrequently, must be assisted and their FEA results need to be checked for plausibility. An automatic plausibility check for finite element (FE) simulations in linear structural mechanics can identify non-plausible simulations and warn the user to interpret the results cautiously or ask for expert help. In this context, currently available tools can only compare very similar simulations. However, as the amount of available simulation data in the industry increases more and more, a data-driven simulation check is an obvious next step. Nevertheless, the question arises how simulation data of very different parts and simulations can be transferred to a single software tool, how this tool can learn the relevant rules behind plausible simulations, and how it can be applied to new simulations. In this context, it is especially important to train a metamodel that is able to generalize the rules so that it can later on be applied to unknown simulations. This paper presents an approach to transfer different FE meshes, corresponding FE results and boundary conditions to an individual matrix of fixed size for very different structural mechanic FE simulation. The novel approach uses spherical detector surfaces to project three-dimensional information on its surface. It allows generating the so-called “DNA of an FE simulation”; classification algorithms i.e. Support Vector Machines or Deep Learning Neural Networks such as Convolutional Neural Networks (CNN) can then classify this information. The whole methodology reduces the dimension of a 3D finite element simulation to a 2D matrix of numeric values. The matrix contains all the relevant information for the classification in “plausible” or “non-plausible”. An implausible simulation contains errors, which would be quickly identified by an experienced simulation engineer, whereas a plausible simulation does not contain such errors. As less experienced simulation users in design departments are not trained to find such errors in their simulation setup, they cannot detect them and take adequate countermeasures. In the paper, every single step of the novel methodology for plausibility checking of structural mechanics simulations will be illustrated and explained in detail for simplified parts and corresponding simulations.<br
Keywords: Plausibility Check; Convolutional Neural Network; Deep Learning; Data-driven approach; design automation; visualization

Methods for integrating postural control into biomechanical human simulations: a systematic review - Shanbhag, Julian; Wolf, Alexander; Wechsler, Iris; Fleischmann, Sophie; Winkler, Jürgen; Leyendecker, Sigrid; Eskofier, Björn; Koelewijn, Anne; Wartzack, Sandro; Miehling, Jörg (Journal of neuroEngineering and rehabilitation, 2023)
Understanding of the human body’s internal processes to maintain balance is fundamental to simulate postural control behaviour. The body uses multiple sensory systems’ information to obtain a reliable estimate about the current body state. This information is used to control the reactive behaviour to maintain balance. To predict a certain motion behaviour with knowledge of the muscle forces, forward dynamic simulations of biomechanical human models can be utilized. We aim to use predictive postural control simulations to give therapy recommendations to patients suffering from postural disorders in the future. It is important to know which types of modelling approaches already exist to apply such predictive forward dynamic simulations. Current literature provides different models that aim to simulate human postural control. We conducted a systematic literature research to identify the different approaches of postural control models. The different approaches are discussed regarding their applied biomechanical models, sensory representation, sensory integration, and control methods in standing and gait simulations. We searched on Scopus, Web of Science and PubMed using a search string, scanned 1253 records, and found 102 studies to be eligible for inclusion. The included studies use different ways for sensory representation and integration, although underlying neural processes still remain unclear. We found that for postural control optimal control methods like linear quadratic regulators and model predictive control methods are used less, when models’ level of details is increasing, and nonlinearities become more important. Considering musculoskeletal models, reflex-based and PD controllers are mainly applied and show promising results, as they aim to create human-like motion behaviour considering physiological processes.
CRIS-Team Scopus Importer:2023-09-01
Keywords: Biomechanical human model; Biomechanics; Forward dynamics; Musculoskeletal model; Postural control; Simulation; Systematic review

Micromotion of Dental Implants: Basic Mechanical Considerations - Winter, Werner; Klein, Daniel; Karl, Matthias (Journal of Medical Engineering, 2013)
Micromotion of dental implants may interfere with the process of osseointegration. Using three different types of virtual biomechanical models, varying contact types between implant and bone were simulated, and implant deformation, bone deformation, and stress at the implant-bone interface were recorded under an axial load of 200 N, which reflects a common biting force. Without friction between implant and bone, a symmetric loading situation of the bone with maximum loading and displacement at the apex of the implant was recorded. The addition of threads led to a decrease in loading and displacement at the apical part, but loading and displacement were also observed at the vertical walls of the implants. Introducing friction between implant and bone decreased global displacement. In a force fit situation, load transfer predominantly occurred in the cervical area of the implant. For freshly inserted implants, micromotion was constant along the vertical walls of the implant, whereas, for osseointegrated implants, the distribution of micromotion depended on the location. In the cervical aspect some minor micromotion in the range of 0.75 μm could be found, while at the most apical part almost no relative displacement between implant and bone occurred.
UnivIS-Import:2015-04-14:Pub.2013.tech.FT.FT-KLMEFK.microm

Micro-scale deterministic asperity contact FEM simulation - Kolli, Vasu; Winkler, Andreas; Wartzack, Sandro; Marian, Max (Surface Topography: Metrology and Properties, 2022)
There are numerous stochastic approaches to indirectly couple solid asperity contact with the fluid hydrodynamics in the region of boundary or mixed lubrication. In contrast, deterministic approaches for calculating solid contact pressure curves offer advantages in terms of flexibility and accuracy. This contribution aims at providing a publicly available, automated method to derive solid asperity contact pressure curves for given surfaces, implemented in commercial software based upon Finite Element Method (FEM). Solid asperity pressure curves were calculated and compared to various established stochastic models for artificially generated surfaces and surfaces measured via laser scanning microscopy. Thereby, it was shown that the usage of artificially generated surfaces based on stochastic parameters only allowed an approximate representation of real measured surfaces as well as to lower calculated pressures, so that 3D measurement data is preferred to calculate the contact pressure. Moreover, the values of the FEM model were in a similar region but slightly below the stochastic models over a wide range of gap distances and the asperity pressure graphs were more curved/convex. At very small gap height values, the pressure in the FEM model reached values similar to the stochastic models. This was attributed to the fact that real surface topographies were considered, also allowing for peak-to-valley pairings instead of merely asperity-to-asperity contacts, as well as to the fact that the roughness and mean planes were re-calculated in each simulation step, while most stochastic approaches neglect the elastic deformation of asperities when determining the distances between the rough surfaces.
Keywords: multiscale modeling; finite element method; solid contact pressure; contact mechanics; tribology

Microstructured surfaces in highly loaded contacts – differences due to sliding effects - Weschta, Martin; Pausch, Michael; Tremmel, Stephan; Wartzack, Sandro (Proc. Society of Tribologists and Lubrication Engineers Annual Meeting and Exhibition 2014, 2014)
Keywords: EHL film geometry; Surface modification

Microstructured surfaces in highly loaded EHD-contacts - manufacturing and tribological performance - Schrader, Tobias; Weschta, Martin; Engel, Ulf; Tremmel, Stephan; Merklein, Marion; Wartzack, Sandro (Proc. 10th International Conference THE "A" Coatings in Manufacturing Engineering, 2013)
In low loaded sliding contacts, as journal bearings or piston contacts, defined microstructures on surfaces were identified for friction reduction purposes and are well established in industrial applications. It is stated that microstructures act as lubricant reservoirs and support lubricant film development. Within the scope of these investigations microstructures are specifically adapted for the tribological load collective of cam follower systems as a representative of highly loaded contacts. For those contacts, the effects of microstructures are still subject of investigations. In this paper a method for efficient microstructuring by micro laser ablation is described. The investigations focus on the determination of the geometric and mechanical properties of the microstructures as well as on the tribological behavior of the microstructured surfaces by two tribological tests.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.micros_0

Microstructured surfaces in highly loaded elastohydrodynamic (EHD)-contacts - manufacturing and tribological performance - Schrader, Tobias; Weschta, Martin; Engel, Ulf; Tremmel, Stephan; Merklein, Marion; Wartzack, Sandro (Materialwissenschaft und Werkstofftechnik, 2013)
In low loaded sliding contacts, as journal bearings or piston contacts, defined microstructures on surfaces were identified for friction reduction purposes and are well established in industrial applications. It is stated that microstructures act as lubricant reservoirs and support lubricant film development. Within the scope of these investigations microstructures are specifically adapted for the tribological load collective of cam follower systems as a representative of highly loaded contacts. For those contacts, the effects of microstructures are still subject of investigations. In this paper a method for efficient microstructuring by micro laser ablation is described. The investigations focus on the determination of the geometric and mechanical properties of the microstructures as well as on the tribological behavior of the microstructured surfaces by two tribological tests.
UnivIS-Import:2015-03-09:Pub.2013.tech.FT.FT-KLMEFK.micros_6
Keywords: EHD-Kontakt; Mikrolaserablation; Mikrostrukturen; Reibversuche; Tribologie

Microstructuring tools for sheet bulk metal forming - a designated application for picosecond laser - Häfner, Tom; Reg, Yvonne; Hetzner, Harald; Schmidt, Michael (Journal of Laser Micro Nanoengineering, 2013)
In addition to coatings, microstructures can increase abrasion-resisting quality of sheet bulk metal forming tools by influencing friction conditions. The use of ultrashort pulsed lasers offers a possibil-ity for manufacturing flexible microstructures with very high precision. Thus the processing with picosecond laser allows the generation of structures with dimensions down to the range of single microns. Because of the characteristic ablation process temperature sensitive materials can be struc-tured without any heat transfer into the material. Applying appropriate processing parameters avoids complex post-finishing processes because of the achieved good structure qualities without any melt and any material throw-up. For implemention of a fast structuring process with high ablation rates it is shown, that only fluences near the ablation threshold allow a processing result of high quality and with the maximum ablation efficiency.
UnivIS-Import:2015-03-09:Pub.2013.tech.FT.FT-KLMEFK.micros
Keywords: Ablation efficiency; Ablation quality; Microstructuring; Picosecond laser; Ultrashort pulsed laser.

Microtextured surfaces in higher loaded rolling-sliding EHL line-contacts - Marian, Max; Tremmel, Stephan; Wartzack, Sandro (Tribology International, 2018)
Due to scarce resources coupled with increasing mobility requirements, resource-efficient machine and motor elements are vital. Therefore, surfaces in lubricated tribological contacts can be microtextured, enabling improved lubricating conditions and friction behavior. While this has already been shown for lower loaded contacts, the effects for higher loaded, application-oriented EHL contacts are topic of basic research. Therefore, geometrically defined microtextures are adapted to the tribological system of the tappet/camshaft contact in the valve train of combustion engines as a demonstrator. The tribological performance in respect to lubricating conditions, friction and wear behavior is analyzed on single cam/tappet component test-rigs. EHL simulation is used as ‘numerical zoom’ into a section of the contact area contributing to better understanding of effects and observed phenomen
Keywords: Surface texture; Friction; Wear; Elastohydrodynamic lubrication

Mikrostrukturierung von Massivumformwerkzeugen mittels Pikosekundenlaser - Häfner, Tom; Reg, Yvonne; Hetzner, Harald (DVS-Berichte Band 288 (2012), 2012)
Eine Möglichkeit zur Steigerung der Ressourceneffizienz von Blechmassivumformwerkzeugen ist die lokale beanspruchungsgerechte Einstellung der Reibungsbedingungen. Die veränderte Reibung zwischen Werkzeug und Werkstück mindert den Werkzeugverschleiß und erhöht damit die Lebensdauer sowie die Reproduzierbarkeit des Umformprozesses. Zusätzlich zur Beschichtung der Umformwerkzeuge ist die Reibungsbeeinflussung durch die Einbringung von flexiblen Mikrostrukturen in die Werkzeugoberfläche realisierbar. Der Einsatz von Pikosekundenlasern bietet die Möglichkeit unter Anwendung entsprechender Prozessparameter, d.h. niedriger Fluenzen, Mikrostrukturen zu erzeugen, die aufgrund des charakteristischen nichtthermischen Ultrakurzpulsabtrags keine Schmelzerückstände aufweisen. Dementsprechend sind temperaturempfindliche Materialien durch den Einsatz von UKP-Lasern bearbeitbar und darüber hinaus ist die gewünschte Flexibilität zur Erzeugung von Strukturen nahezu beliebiger Geometrien gegeben.
UnivIS-Import:2015-04-16:Pub.2012.tech.FT.FT-KLMEFK.mikros

Mikrostrukturierung von Tassenstößeln zur Reibungsreduzierung im Ventiltrieb – Herstellung, Simulation und tribologische Charakterisierung - Weschta, Martin; Schrader, Tobias; Tremmel, Stephan; Merklein, Marion; Wartzack, Sandro; Engel, Ulf (Tribologie und Schmierungstechnik, 2014)
Im Rahmen der in einem Verbundprojekt durchgeführten Untersuchungen wurden Mikrostrukturen mit dem Ziel der Reibungsreduzierung speziell an das tribologische System eines Nocken/Stößel-Kontaktes, als Beispiel für hochbelastete Wälz-Gleit-Kontakte, angepasst. Für diese Art von Reibkontakten sind die Effekte von Mikrostrukturen noch nicht abschließend geklärt. Zur Erlangung disziplinübergreifender Erkenntnisse wurden Mikrostrukturformen durch numerische Simulationen ausgelegt sowie die Genauigkeit der Fertigung und das tribologische Verhalten der mikrostrukturierten Komponenten untersucht. Für die Herstellung der Mikrostrukturen wurde aufgrund der Perspektive für die Großserienanwendung auf den Prozess des Mikroprägens fokussiert, der der Mikrolaserablation hinsichtlich seiner Genauigkeit gegenübergestellt wurde. Für die mikrostrukturierten Ventiltassenoberflächen wurde im Prüfstand eine signifikante Reibungsreduzierung gegenüber polierten Oberflächen erreicht.
LFT Import::2019-07-29 (1977)

Mikrostrukturierung von Tassenstößeln zur Reibungsreduzierung im Ventiltrieb - Herstellung, Simulation und tribologische Charakterisierung - Weschta, Martin; Schrader, Tobias; Tremmel, Stephan; Merklein, Marion; Wartzack, Sandro; Engel, Ulf (54. Tribologie-Fachtagung. Reibung, Schmierung und Verschleiß. Band II, 2013)
Im Rahmen der in einem Verbundprojekt durchgeführten Untersuchungen wurden Mikrostrukturen mit dem Ziel der Reibungsreduzierung speziell an das tribologische System eines Nocken-Stößel-Kontaktes, als Beispiel für hochbelastete Wälz-Gleit-Kontakte, angepasst. Für diese Art von Reibkontakten sind die Effekte von Mikrostrukturen noch nicht abschließend geklärt. Zur Erlangung disziplinübergreifender Erkenntnisse wurden Mikrostrukturformen durch numerische Simulationen ausgelegt sowie die Genauigkeit der Fertigung und das tribologische Verhalten der mikrostrukturierten Komponenten untersucht. Die tribologische Wirkung der Mikrostrukturen wurde in einem zweidimensionalen elastohydrodynamischen Simulationsmodell bestimmt. Für die Herstellung der Mikrostrukturen wurde aufgrund der Perspektive zur Großserienanwendung auf den Prozess des Mikroprägens fokussiert, der der Mikrolaserablation hinsichtlich seiner Genauigkeit gegenübergestellt wurde. Für die mikrostrukturierten Ventiltassenoberflächen wurde im Prüfstand eine signifikante Reibungsreduzierung gegenüber polierten Oberflächen erreicht.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.mikros

Mikrostrukturierung von Werkzeugstählen mittels Ultrakurzpulslasern - Häfner, Tom; Reg, Yvonne; Hetzner, Harald; Schmidt, Michael (15. Erlanger Seminar LEF 2012 Vol. 15 pp. 169-184 (2012), 2012)
Eine zukunftsorientierte Alternative für die Mikrobearbeitung von harten, schwer zerspanbaren und temperaturempfindlichen Werkstoffen stellen Ultrakurzpulslaser (UKP-Laser) und hierbei insbesondere Pikosekundenlaser dar. Denn mit dem Werkzeug UKP-Laser können basierend auf dem Prozess des UKP-Abtrags Oberflächendimensionen bis hinunter in den einstelligen Mikrometerbereich ohne Werkzeugverschleiß und nahezu ohne unerwünschte Temperatureinbringung erzeugt werden. Zusätzlich unterstützt wird diese Entwicklung sowohl in der Forschung als auch in der industriellen Fertigung durch die Verfügbarkeit von Pikosekundenlasern steigender Leistungsfähigkeit. Anwendung finden die Strahlquellen unter anderem in der Mikrostrukturierung von Halbzeugen. Voraussetzung für eine qualitätsgerechte Herstellung dieser Strukturen ist ein materialspezifisches Prozessverständnis. Vor diesem Hintergrund zeigt der Beitrag auf, welche Kenntnisse der Zusammenhänge zwischen Prozessparametern und entstehenden Struktureigenschaften beim UKP-Abtrag für die Definition eines Prozessfensters notwendig sind.
Keywords: Laserstrukturierung; Pikosekundenlaser

MiniDES - Lightweight Python Simulation Framework for Interconnected Renewable Resources - Schlund, Jonas; Reisenweber, Julian; German, Reinhard (Proceedings of the IEEE Green Energy and Smart Systems Conference 2019, 2019)
Photovoltaic systems and battery storages are increasingly installed on distribution feeders. As the digitization of the grid evolves, collective control paradigms of distributed assets become possible. The proposed simulator MiniDES is a generic python framework to model and interconnect such distributed assets in flexible control scenarios and modular simulation setups. An integrated aggregator model allows for versatile queries, different state-dependent control setups as well as postprocessing all data obtained during simulation. The framework is available as open source, portable and offers a template with household scenarios to build upon. In addition, the simulator can easily be coupled with the electric power system simulator OpenDSS in order to include a power flow analysis. An exemplary case study collectively optimizes the inverter power of a 20 household community, each with a rooftop photovoltaic plant and a battery, and achieves loss savings of 33% as well as considerable increases in self-sufficiency in comparison to the individual control case. The according power flow analysis showed that the increased line losses caused by the increased grid utilization of the collective control case are negligible compared to the loss savings. In addition, our simulation shows that the beneficial community control is economically infeasible with a conventional price mechanism and that economic feasibility can be achieved by introducing a more dynamic price mechanis
Keywords: renewable energy; smart grid; simulation framework; solar power; energy storage; optimization

Minimal Data, Maximal Impact: Language Model-based Pipelines for the Automatic Generation of Use Case Diagrams from Requirements - Schleifer, Simon; Lungu, Adriana; Kruse, Benjamin; van Putten, Sebastiaan; Götz, Stefan; Wartzack, Sandro (35. Symposium - Design for X (DfX), 2024)
Striving for unique selling points leads to an increase in product requirements, which are prevalently written in natural language. In order to mitigate inherent ambiguities in these requirements specifications, methods of Model-Based Systems Engineering, like use case diagrams, can be utilized. However, creating model-based requirements is time-consuming. Thus, two novel pipelines for the automatic generation of use case diagrams are proposed and discussed with focus on reducing the amount of needed annotated training data. The first pipeline combines named entity recognition with active learning. The second pipeline utilizes generative large language models and prompt engineering. Both pipelines are exemplarily applied to a requirements specification from the automotive industr
Keywords: Use case diagrams; Natural language processing (NLP); Large language models (LLM); Model-based systems engineering (MBSE); Requirements engineering (RE)

Mit Bürgerinnen und Bürgern über Forschung und technische Innovationen in der Palliativversorgung ins Gespräch kommen – Pilotierung eines ELSI-Cafés - Öhl, Natalie; Weisser, Alina; Ott, Tabea; Grießhammer, Stefan; Yip, Julia; Klinger, Isabell; Kölpin, Alexander; Miehling, Jörg; Bräuning, J.; Dabrock, Peter; Steigleder, Tobias; Ostgathe, Christoph; et al. (Zeitschrift für Palliativmedizin, 2024)

Modal synthesis of belt-rib structures - Hasse, Alexander; Zuest, I.; Campanile, Lucio Flavio (Proceedings of the Institution of Mechanical Engineers Part C-Journal of Mechanical Engineering Science, 2011)
In contrast to conventional mechanisms, compliant mechanisms exploit structural flexibility to produce controllable large deformations. Belt-rib airfoils are shape-adaptable lightweight structures based on this idea. A belt-rib structure originally consists of a deformable closed shell (belt) whose kinematic degrees of freedom are constrained by inner stiffeners called spokes. Using standard spoke elements, the possible profile changes of the airfoil are limited. The purpose of the work reported in the current article is to define an inner stiffening structure based on numerical topology optimization in order to realize arbitrary profile changes. A ground structure with moveable connection points within the external belt represents the set of possible topologies and shapes. A new modal objective function for the synthesis of compliant mechanisms with selective compliance is introduced. The optimization problem is approached by using genetic algorithms. The applicability of the current procedure is validated by a profile shape adaptation example. For this purpose, an initial profile shape and a target profile shape are defined. The outcome of the procedure is a complex inner stiffening structure, which fulfils the imposed requirements. The solution is validated by modal analysis based on an finite-element model. Furthermore, the structural behaviour is experimentally investigated. In contrast to conventional mechanisms, compliant mechanisms exploit structural flexibility to produce controllable large deformations. Belt-rib airfoils are shape-adaptable lightweight structures based on this idea. A belt-rib structure originally consists of a deformable closed shell (belt) whose kinematic degrees of freedom are constrained by inner stiffeners called spokes. Using standard spoke elements, the possible profile changes of the airfoil are limited. The purpose of the work reported in the current article is to define an inner stiffening structure based on numerical topology optimization in order to realize arbitrary profile changes. A ground structure with moveable connection points within the external belt represents the set of possible topologies and shapes. A new modal objective function for the synthesis of compliant mechanisms with selective compliance is introduced. The optimization problem is approached by using genetic algorithms. The applicability of the current procedure is validated by a profile shape adaptation example. For this purpose, an initial profile shape and a target profile shape are defined. The outcome of the procedure is a complex inner stiffening structure, which fulfils the imposed requirements. The solution is validated by modal analysis based on an finite-element model. Furthermore, the structural behaviour is experimentally investigated. © Authors 2010.
Keywords: belt rib; compliant mechanisms; morphing; shape adaptation; shape control

Model and Knowledge Representation for the Reuse of Design Process Knowledge Supporting Design Automation in Mass Customization - Dworschak, Fabian; Kügler, Patricia; Schleich, Benjamin; Wartzack, Sandro (Applied Sciences, 2021)
Mass customization aims to meet individual requirements and, therefore, is one way to attract and retain customers—a key challenge in the design industry. The increase in design automation has offered new opportunities to design customized products at high speed in a way that is cost equivalent to mass production. Design automation is built upon the reuse of product and process knowledge. Ontologies have proven to be a feasible, highly aggregated knowledge representation in engineering design. While product and process knowledge from other lifecycle phases are represented in multiple approaches, the design process of the product as well as the adaption process of product variants is missing, causing breakpoints or additional iterations in design automation. Therefore, suitable knowledge representation tailored to design automation is still missing. Accordingly, this contribution proposes a novel knowledge representation approach to enable design automation for mass customization. Methodically, this novel approach uses semantic enrichment of CAD environments to automatically deduce information about a design task, design rationale, and design process represented by a formal ontology. The integration of the design process significantly differentiates the approach from previous ones. The feasibility of the approach is demonstrated by a bike crank customization process.
Keywords: knowledge reuse; knowledge representation; ontology; design automation; mass customization

Model Factory for Additive Manufacturing of Mechatronic Products: Interconnecting World-Class Technology Partnerships with Leading AM Players - Yoo, In Seong; Braun, Thomas; Kästle, Christopher; Spahr, Michael; Kestel, Philipp; Wartzack, Sandro; Franke, Jörg; Bromberger, Jörg; Feige, Erhard (6th CIRP Conference on Learning Factories, 2016)
The additive manufacturing (AM) model factory’s aim is to establish a leading-edge learning academy for the digital and generative production of innovative mechatronic products, where the complete value chain is integrated on a single site. Short courses and deep dives enable easier access to the state of the art technologies and increase the awareness for their potentials. Anchored in key industries such as automotive, aerospace, and medical by major OEMs and regional SMEs, the AM model factory cooperates with world-class partners and leading market players. This paper displays the model factory’s setup, selected technologies, exemplary courses, and benefits.

Modeling of cage guidance in a rolling bearing multi-body dynamic simulation program for a power efficient bearing design - Seiler, Katrin; Stadler, Marion; Tremmel, Stephan; Hahn, Bodo; Wartzack, Sandro; Graf-Goller, Oliver (Volume 2, 2014)
Keywords: Wälzlager; MKS; Tribologie; Hydrodynamik

Modeling of Shape Deviations for the Development of Predictive Models of TEHD Contacts - Feile, Klara; Bartz, Marcel; Wartzack, Sandro (24, 2024)

Modellierung bandgeführter Gelenke der Hand zur Anwendung bei klinischen und biomechanischen Fragestellungen - Miehling, Jörg; Krüger, Daniel; Quadrat, Eric; Jalali, Jalil; Erne, Holger C.; Cerny, Michael; Wartzack, Sandro; Kovacs, Laszlo (6. caMe-Konferenz, 2016)
One of the most common injuries, not only in work-related environments, are hand injuries. In many cases, those are treated by rigid connections of parts or the entire wrist to alleviate the symptoms. This can cause a high limitation of workability and quality of life. Despite all scientific efforts, the biomechanics of the wrist with its complex support structure are still not entirely understood. Frequent injury patterns which lead to painful, arthritic changes and restrictions of the range of motion, cause problems in clinical practice. Often the currently used surgical techniques for reconstructing damaged structures only reach limited success. Additionally the diagnosis and the treatment of many injuries are vague and difficult. For example the functions and interactions of the hand structures are not completely clarified, whether a surgery is useful or not. This problem can only be solved with collaboration of engineering and medical expertise. The main goal of this contribution is to create a simulation model of the hand in order to facilitate a realistic representation and analysis of the interaction between the bones. Thereby future injuries could be better understood, diagnosed and treated. To sum up, a validated 3D hand model focusing on the wrist offers a vast number of possibilities in clinical practice as well as in basic research, such as the detailed exploration of the functional relationships in the wrist. Furthermore there is a positive influence on socio-economic factors, because earlier diagnosis and individualized therapies can minimize the duration of disability and also avoid occupational disability. When developing product and process innovations, the human ever more moves into the center of consideration. In fact, the available human hand models are not detailed enough, for example to describe realistic grasping motions, which are crucial for manual assembly tasks as well as for most user-product interactions. Beside clinical practices, the developed bone and ligament-guided model should also be used in system simulations to adjust work processes and products to compy with the biomechanical requirements of workers or users. Thus, congestion can be uncovered and avoided in early planning stages.
Keywords: hand model; musculoskeletal system; multibody simulation; biomechanics; surgical planning; orthopedics; ergonomics

Modellierung der Käfigführung für Wälzlagerdynamiksimulationsprogramme – Ein Beitrag zur betriebssicheren Lagerauslegung - Seiler, Katrin; Stadler, Marion; Tremmel, Stephan; Hahn, Bodo; Wartzack, Sandro; Graf-Goller, Oliver (Tribologie und Schmierungstechnik, 2013)
In dem Beitrag wird ein analytisches Berechnungsmodell für die Abbildung der Hydrodynamik im Käfig/Ring- Kontakt von Wälzlagern näher betrachtet. Dieses Modell beinhaltet die Berechnung der Kontaktnormalkraft, der Schmierstoffdämpfung und der Reibung resultierend aus der Schmierstoffscherung bei geschmierten Kontakten. Im Fall des bordgeführten Käfigs wird auf die Kurzgleitlager- Theorie zurückgegriffen. Das Berechnungsmodell für den hydrodynamischen Kontakt wurde in das Wälzlagermehrkörpersimulationsprogramm CABA3D implementiert und mit dem Gleitlagerberechnungsprogramm COMBROS abgeglichen. Anhand von Simulationsergebnissen für ein fliehkraftbeanspruchtes Nadellager wird exemplarisch der Einfluss der Hydrodynamik im Käfig/Ring-Kontakt auf das Lagergesamtreibmoment und die Lagerkinematik dargestellt.
Keywords: Wälzlager; MKS; Tribologie

Modellierung der Käfigführung für Wälzlagerdynamiksimulationsprogramme – Ein Beitrag zur betriebssicheren Lagerauslegung - Seiler, Katrin; Stadler, Marion; Tremmel, Stephan; Hahn, Bodo; Wartzack, Sandro; Graf-Goller, Oliver (54. Tribologie-Fachtagung. Reibung, Schmierung und Verschleiß. Band II, 2013)
In dem Beitrag wird ein analytisches Berechnungsmodell für die Abbildung der Hydrodynamik im Käfig/Ring-Kontakt von Wälzlagern näher betrachtet. Dieses Modell beinhaltet die Berechnung der Kontaktnormalkraft, der Schmierstoffdämpfung und der Reibung resultierend aus der Schmierstoffscherung bei geschmierten Kontakten. Im Fall des bordgeführten Käfigs wird auf die Kurzgleitlager-Theorie zurückgegriffen. Das Berechnungsmodell für den hydrodynamischen Kontakt wurde in das Wälzlagermehr-körpersimulationsprogramm CABA3D implementiert und mit dem Gleitlagerberechnungsprogramm COMBROS abgeglichen. Anhand von Simulationsergebnissen für ein fliehkraftbeanspruchtes Nadellager wird exemplarisch der Einfluss der Hydrodynamik im Käfig/Ring-Kontakt auf das Lagergesamtreibmoment und die Lagerkinematik dargestellt. Analytical models for the calculation of hydrodynamics in the contact between cage and ring of roller bearings will be presented in this article. The model contains the calculation of the contact normal force, the lubricant damping and the friction resulting from lubricant shear. In case of the contact between cage and ring in rib guided bearings the hydrodynamic model is based on the theory of a journal short bearing. The hydrodynamic model was implemented in a multibody system for roller bearings named Caba3D and the results are compared to a journal bearing calculation program named COMBROS. Simulation results show exemplary the influence of hydrodynamics on friction and kinematics of a needle bearing under centripetal load.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.modell
Keywords: Wälzlager; MKS; Tribologie; Hydrodynamik

Modelling, Construction and Manufacture of a Lightweight Robot Arm - Hagenah, Hinnerk; Böhm, Wolfgang; Breitsprecher, Thilo; Merklein, Marion; Wartzack, Sandro (Proceedings of the 8th CIRP International Conference on Intelligent Computation in Manufacturing Engineering, 2012)
This contribution will show how modern materials as cellular titanium and nanocrystalline aluminium can be used to build advanced lightweight robot arms. Cellular titanium allowing a specific density distribution and the manufacture of fine structures with desirable properties is produced by selective electron beam melting while the nanocrystalline aluminium results from accumulative roll bonding. The specific properties of both materials will be highlighted. The paper will cover the definition of the product specification, the setting of a basic design and the optimisation of this by means of topology optimisation. This optimisation requires an intelligent modelling to be able to investigate different initial settings and boundary conditions. The optimised part will then be finished with regards to manufacturability. The paper will close with a brief report about the actual manufacture of one of the investigated variants.
UnivIS-Import:2015-04-16:Pub.2012.tech.FT.FT-KLMEFK.modell

Modelling postural control of upright standing during translational perturbations - Shanbhag, Julian; Fleischmann, Sophie; Gaßner, Heiko; Winkler, Jürgen; Eskofier, Björn; Koelewijn, Anne; Wartzack, Sandro; Miehling, Jörg (29th Congress of the European Society of Biomechanics, 2024)

Modelling the interaction between wearable assistive devices and digital human models—A systematic review - Scherb, David; Wartzack, Sandro; Miehling, Jörg (Frontiers in Bioengineering and Biotechnology, 2023)
Exoskeletons, orthoses, exosuits, assisting robots and such devices referred to as wearable assistive devices are devices designed to augment or protect the human body by applying and transmitting force. Due to the problems concerning cost- and time-consuming user tests, in addition to the possibility to test different configurations of a device, the avoidance of a prototype and many more advantages, digital human models become more and more popular for evaluating the effects of wearable assistive devices on humans. The key indicator for the efficiency of assistance is the interface between device and human, consisting mainly of the soft biological tissue. However, the soft biological tissue is mostly missing in digital human models due to their rigid body dynamics. Therefore, this systematic review aims to identify interaction modelling approaches between wearable assistive devices and digital human models and especially to study how the soft biological tissue is considered in the simulation. The review revealed four interaction modelling approaches, which differ in their accuracy to recreate the occurring interactions in reality. Furthermore, within these approaches there are some incorporating the appearing relative motion between device and human body due to the soft biological tissue in the simulation. The influence of the soft biological tissue on the force transmission due to energy absorption on the other side is not considered in any publication yet. Therefore, the development of an approach to integrate the viscoelastic behaviour of soft biological tissue in the digital human models could improve the design of the wearable assistive devices and thus increase its efficiency and efficac
Keywords: digital human model; musculoskeletal modelling; multi-body dynamic; interaction modelling; systematic review; soft tissue; wearable assistive device

Modifikation der Methode der Dimensionsreduktion zur Berechnung von beliebigen Punkt- und Ellipsenkontakten in Wälzlagern - Wirsching, Sven; Bänsch, Dominik; Bartz, Marcel; Wartzack, Sandro (62. Tribologie-Fachtagung 2021 Reibung, Schmierung und Verschleiß Forschung und praktische Anwendungen, 2021)
Inside rolling bearings, there is a large number of different contacts. These include not only linear contacts on the raceways, the cage and the rolling elements, but also point and elliptical contacts between the rolling element end face and the ring rib. Depending on the load situation, these contacts contribute differently to the load carrying capacity, the temperature development and thus the operating capability of the rolling bearing. The axial load carrying capacity of roller bearings is determined primarily by the rib contact, since the axial load components are absorbed by the ribs. To calculate the load capacity, an exact description of the contact between the rolling element end face and the ring rib is necessary. An improved contact calculation allows the targeted development of more efficient and higher-performance rolling bearings. In existing methods for dimensioning rolling bearings, the contact between the rolling element and rib is calculated on the basis of the time- and resource-efficient theory of Hertz, which makes simplifications in the description of the geometries. However, contacts of real, complex geometry pairings of rolling element and rib, as used to optimize the axial load capacity of roller bearings, can only be calculated inaccurately with this method. Compared with time-consuming, high-quality numerical calculations (e.g. finite element analysis), there are greater discrepancies in the size of the contact area and contact pressures. For this reason, this paper presents a new time- and resource-efficient method for the calculation of point and elliptical contacts. Using the method of dimensional reduction (MDR) according to Popov, contacts of rotationally symmetric bodies can be calculated exactly. A modification of MDR allows the calculation of non-rotationally symmetric bodies. The existing contact situation is described and calculated with a superposition of different rotationally symmetric geometries. The modified MDR is compared with the Hertz theory using simple contact situations. The results for more complex contact situations are compared with those from finite element analyses. By comparing the calculated contact area and contact pressure, the possibilities and limitations of the modified MDR are ass
Keywords: contact mechanics; MDR; point contact; ellipse contact; bearings

Modular rapid design of multi-material lightweight truss structures – A novel approach - Rathert, Thomas; Witzgall, Christian; Wartzack, Sandro (Book of Abstracts. Symposium Lightweight Design in Product Development, Zurich, 2018)
The specification of an ideal lightweight design with minimal weight and maximum utilization of the material is often restricted by economic factors. Taking this into account, only an optimized lightweight design can be realized. When utilizing modern composite materials, the design and manufacturing methods are poorly standardized and their implementation usually causes high costs in design and production. Besides that the composite suitability of framework structures – which could be standardized – is only given for uniaxial loaded sections, whereas the connector regions are subject to a (at least) biaxial stress state that is very unfavorable for composite materials. As a consequence it is often advisable to use a multi-material design – also known as hybrid design. The best properties of different materials are combined here, while keeping the economic impact as low as possible. Each individual element of the hybrid structure offers a basic local solution, but in addition they can achieve optimization in a combined state. The main objective of this contribution is to show how to simply use the right material in the right place, thus allowing to optimally exploiting their beneficial lightweight properties and keeping the costs as low as possible. Therefore a methodology is presented, which allows the dimensioning and optimization of multi-material lightweight design systems inside a restricted design space by using modular and rapid building blocks. This enables the product developer to design an optimal framework topology by using a discrete optimization approach and afterwards dimension anisotropic composite tubes for the sections of uniaxial stresses and isotropic connectors to join them. The calculated information is then transferred to the CAD‑System to directly create the product’s embodiment design by using standardized composite profiles and aluminum connectors. Finally using the demonstrator of a motorcycle frame, the method will be evaluated and discussed.
Keywords: hybrid design; multi-material design; discrete topology optimization

Monitoring a property based product development From requirements to a mature product - Krehmer, Hartmut; Meerkamm, Harald; Wartzack, Sandro (Proceedings of the 18th International Conference on Engineering 2011 (ICED 11), 2011)
Increasing customers̀ requirements as well as changing market demands are just two examples for influences that result in an increasing complexity of technical products. To assure the fulfilment of all requirements an effective monitoring of product development is essential. Monitoring is often done by observance of required time and caused costs, and does not take into account product's functionality or properties or behaviour. This contribution introduces a framework which allows combining different approaches for efficient monitoring of product development by focusing the products'properties from requirements to a mature product. Therefore, at first a short introduction in property based product development is given and a model for property based development is introduced, before existing methods for evaluating and monitoring product development are depicted. After that an introduction in monitoring product development is given and approaches are integrated into the model of property based product development with regard to their capabilities and focuses. Finally, this results in an approach for monitoring property based product development from requirements to a mature product.
UnivIS-Import:2015-04-16:Pub.2011.tech.FT.FT-KLMEFK.monito
Keywords: Monitoring; Product's degree of maturity; Property based product development

Monte Carlo simulation of the MoS2 sputtering process and the influence of the normalized momentum on residual stresses - Vierneusel, Bernd; Tremmel, Stephan; Wartzack, Sandro (Journal of Vacuum Science & Technology A, 2015)
UnivIS-Import:2015-10-26:Pub.2015.tech.FT.FT-KLMEFK.montec

Motion Tolerancing Based on Skin Model Shapes by Form Deviation Parametrization and Meta-Modelling - Schleich, Benjamin; Wartzack, Sandro (ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Volume 1: 37th Computers and Information in Engineering Conference, 2017)
The inevitable presence of geometrical part deviations and their effects on the product function and quality forces companies to manage these deviations along the product life-cycle. Computer-aided tolerancing and variation simulation tools support these activities by enabling the early prediction and assessment of the effects of such part deviations. However, available approaches for the tolerance analysis and variation simulation imply shortcomings regarding the consideration of form deviations, particularly when analysing mechanism and moving systems. This paper presents an approach for the motion tolerancing, i. e. for the tolerance analysis of mechanism and moving systems, employing discrete geometry representations of parts with geometrical deviations (Skin Model Shapes). In this regard, a novel method for the parametrization of form deviations is proposed and the use of meta-modelling techniques for the reduction of the computational effort is illustrated. Moreover, the presented approach is applied on two case studies. Based on the obtained results, it can be found, that the consideration of form deviations in the tolerance analysis for mechanism and moving systems may lead to more purposeful tolerancing decisions.

Multi-body simulation of an ankle foot orthosis mechanics - Steck, Patrick; Scherb, David; Miehling, Jörg; Wartzack, Sandro (Proceedings from the NAFEMS DACH Conference 2024, 2024)
In Germany, more than 200,000 first strokes and over 70,000 recurrent strokes occur every year. A stroke often leads to damage to the central nervous system, which is responsible for signal transmission and processing between the brain and muscles, among other things. This results in disorders of the musculoskeletal system, which in turn can lead to pathophysiological movement. In this case, the maximum forces exerted by the lower leg muscles are reduced. A mechanical concept for a passive ankle orthosis is currently being developed at the KTmfk, which help to support the complete gait cycle of patients in the future. Initially, movement data was collected from healthy test subjects. The human model simulation software OpenSim was then used to determine the support curves required by the ankle orthosis for patients with various states of weakness. These sequences were then imported into Ansys Motion in order to simulate the various switching processes within the mechanism during the entire gait cycle. During a gait phase (e.g. roll-off phase), a resulting displacement is calculated, which leads to an increase in the energy stored in the orthosis. This in turn can be released in other gait phases (e.g. the push-off phase) and thus provide a corresponding support force. The temporal sequence of the release moments was integrated into an Ansys Workbench and the resulting signals were passed on to linked components. Various design points were then initialized at which optimal energy storage can be calculated using torsion springs. The parameter optimization of the components relevant for energy storage runs parallel to other musculoskeletal simulations and ultimately ensures support adapted to the patient.<br
Keywords: Mulit-Body Simulation; Orthoses; Design for Medical Devices; AFO; Conceptual Design

Multi-criteria evaluation and decision making on the basis of the matrix-based modeling of the product development - Luft, Thomas; Wartzack, Sandro (Proceedings of 3rd International Spring School on Systems Engineering 2015, 2015)

Musculoskeletal modeling of user groups for virtual product and process development - Miehling, Jörg (Computer Methods in Biomechanics and Biomedical Engineering, 2019)
Although biomechanical digital human models find their way into virtual engineering processes, biomechanical considerations are currently still unrecognized to a large extent. One major obstacle lies in the fact that even though subject-specific modeling procedures are developed, virtual user groups or populations are still missing. The objective of this contribution is to create such groups of musculoskeletal models. Therefore, a modeling procedure based upon population data is described. First of all, two generic three-dimensional models, one with female and one with male average anthropometric dimensions, were obtained. These models constitute the starting point for the following model adjustment phases. Evenly distributed dimensionless values for gender, age, height, mass, range of motion and strength are sampled and translated into more expressive parameters for the mentioned modeling domains serving as input data for the creation of each individual model of the desired population or user group. The most sophisticated step of the adaption is the strength mapping aiming to create models matching arbitrary target joint torques. Finally, the models’ maximal strength is assessed in a manual material handling task and compared to empirical strength data. The approach is shown using the example of the German population.
CRIS-Team Scopus Importer:2019-08-27
Keywords: action force; Digital human model population; musculoskeletal modeling; population data; strength adaption

Musculoskeletal Simulation and Evaluation of Support System Designs - Miehling, Jörg; Wolf, Alexander; Wartzack, Sandro (Developing Support Technologies - Integrating Multiple Perspectives to Create Assistance that People Really Want, 2018)

Musculoskeletal simulation for human-centred engineering of wearable assistive devices - Scherb, David; Steck, Patrick; Wartzack, Sandro; Miehling, Jörg (29th Congress of the European Society of Biomechanics, 2024)

Mxene nanosheets as an emerging solid lubricant for machine Elements – Towards increased energy efficiency and service life - Marian, Max; Tremmel, Stephan; Wartzack, Sandro; Song, Guichen; Wang, Bo; Yu, Jinhong; Rosenkranz, Andreas (Applied Surface Science, 2020)
Solid lubricants like carbon-based materials, transition metal dichalcogenide compounds, polymers and soft metals, each with their specific merits and limitations, pursue the goal of reducing friction and wear between two rubbing surfaces under substantially dry conditions. Newly emerging early transition metal carbides and carbonitrides, such as Ti3C2Tx-nanosheets (MXenes), seem to be a promising candidate to be used as a solid lubricant due to their weakly bonded multilayer structure with self-lubricating character. For the first time, this paper aims at addressing the application of MXene nanosheets in higher loaded rolling-sliding contacts of machine elements by investigating their friction and wear behavior in thrust ball bearings under ambient conditions. Thereby, a reduction of the frictional torque by a factor of up to 3.2, an extension of the service life by about 2.1 times and a decrease of the linear cumulative wear rate by up to 2.9 compared to uncoated references have been verified. Thus, the Ti3C2Tx-coating already featured results comparable to reports on graphene, amorphous carbon coatings or advanced transition metal dichalcogenide, which demonstrates the tremendous potential of MXene nanosheets as outstanding, next-generation solid lubricant in machine elements.<br
Keywords: 2D materials; Ti3C2Tx-nanosheets; solid lubricants; machine elements; thrust ball bearing

Natural Finger Interaction for CAD Assembly Modeling - Fechter, Marius; Wartzack, Sandro (ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Volume 1: 37th Computers and Information in Engineering Conference, 2017)
In current CAD software the process of assembly modeling is hindered by a large number of separate rotation and translation actions necessary, especially in case of larger assemblies. Additionally matching faces, edges or points must be selected by clicking to define the appropriate constraint. In contrast to that, the process of assembling two normal sized physical parts in the real world seems to be rather simple. That is because we know how to grasp and move objects with our hands intuitively from our everyday experience. The idea behind this contribution is to enable the product developer to assemble CAD parts in a virtual environment through natural finger interaction like in reality. Therefore we present an overall method that combines the natural finger interaction with virtual objects and the insertion of constraints between rotationally symmetric CAD parts. The developed algorithms identify matching surfaces on the basis of the geometry as well as position and orientation of the parts in 3D space. This paper highlights the method to use a combination of real-time physics simulation and a heuristic approach to achieve an intuitive interaction interface. Additionally, we describe the detection algorithms developed to find assembly relationships between rotationally symmetric CAD parts without prior constraint definition. We also present a prototype system to demonstrate the functionality of the overall method. Furthermore, challenges for future research, such as extending the functionality of the detection algorithms on additional part types, like non-rotationally symmetric shapes, are discussed.
Keywords: Assembly Modeling; Computer-Aided Design; Virtual Reality; Natural User Interface

Natural Language Processing in Requirements Engineering and Its Challenges for Requirements Modelling in the Engineering Design Domain - van Remmen, Judith Sophie; Horber, Dennis; Lungu, Adriana; Chang, Fan; van Putten, Sebastiaan; Götz, Stefan; Wartzack, Sandro (Proceedings of the Design Society, 2023)
Requirements represent a central element in product development. The large number of requirements inevitably results in an increased susceptibility to errors, an expenditure of time and development costs. The associated problems motivate the application of Artificial Intelligence in the form of Natural Language Processing (NLP). In Requirements Engineering one main task is the classification of requirements which serves as the input in architectural models e.g. in SysML. In mechanical engineering there is still little overview regarding the interface between requirements classification and modelling. This paper provides an overview of the requirement classes and entities used in the literature and analyses their utilisation in modelling. Existing requirements classes usually do not offer the flexibility to be transferred to other domains. However, basic structures can be adopted from those classifications. This enables a clear assignment of existing classes to object classes in modelling. Resulting from the conducted literature study the observed predominant focus of research on the software industry requires an extension of the existing requirement classes and entities to enable further use and transfer to mechanical engineerin
Keywords: Requirements; Artificial intelligence; Natural Language Processing; Systems Engineering (SE); Literature review

Natural VR modeling: a viable alternative to freehand sketching for preliminary design? - Harlan, Jakob; Götz, Stefan; Wartzack, Sandro (Design Science, 2025)
The ideating phase of product design is critical, as decisions made here influence the rest of the product’s lifecycle. Usually, early preliminary designs in engineering are created with pen and paper, which are incompatible with the subsequent digital design process. In an effort to find a modeling tool for early designs that provides the creative flexibility of freehand sketching but also the further processability of digital models, this research investigates natural modeling in virtual reality (VR). To do so, a VR modeling method allowing the intuitive creation of preliminary designs as simplified computer-aided design (CAD) models is presented. The main contribution is the evaluation of this natural VR modeling method against freehand sketching in an extensive user stud
Keywords: Virtual Reality (VR); Computer-Aided Design (CAD); Preliminary Design; Engineering Design; Natural User Interfaces

New Approach on the Allocation of Wear Allowances - a Case Study - Schubert, Dominik; Rohrmoser, Andreas; Hertle, Sebastian; Wartzack, Sandro; Hagenah, Hinnerk; Merklein, Marion; Drummer, Dietmar (22nd International Conference on Engineering Design (ICED19), 2019)

Nodal force distribution of moments on arbitrarily shaped geometries without multi-point constraints - Jäger, Michael; Wartzack, Sandro (Engineering With Computers, 2025)
This paper presents a new approach for converting external moments into nodal forces for the Solid Finite Element Analysis. The proposed approach accurately distributes loads on arbitrarily shaped geometries by utilising the vertices of the Finite Element mesh as a point cloud. This eliminates the need for additional elements and Multi-Point Constraints, overcoming the challenges, complexity and computational cost introduced by these constraints. The proposed approach offers a precise and lightweight solution that enhances the performance of design optimisation scenarios with multi-axial moments on complex, non-convex surfaces. The paper presents comprehensive results that validate the effectiveness and accuracy of the proposed approach, particularly in engineering design optimisation scenarios that require a large number of simulations, such as the topology optimisation of truss nodes. Overall, this method offers a practical and efficient approach for handling moments in Solid Finite Element Analysis. In the presented example, computational cost and complexity were reduced by approximately 14 % compared to commonly used methods for solving Multi-Point Constraint
Keywords: Solid finite element analysis; Nodal forces; Multi-point constraints; Moment load; Point cloud; Optimisation

Non-Dimensional Groups, Film Thickness Equations and Correction Factors for Elastohydrodynamic Lubrication: A Review - Marian, Max; Bartz, Marcel; Wartzack, Sandro; Rosenkranz, Andreas (Lubricants, 2020)
Apart from complex numerical models to predict the tribological behavior of elastohydrodynamically lubricated contacts, non-dimensional similarity groups and analytically solvable proximity equations can be used to estimate integral fluid film parameters. Based upon the pioneering work presented by Dowson and Higginson as well as Blok and Moes, these approaches have been continuously improved over the years by modifications or correction factors to capture different contact geometries (line-, point- or elliptical contacts) as well as to include fluid compression, thermal, non-Newtonian, starvation or roughness effects. Consequently, this review article aims at systematically reviewing these modifications/corrections and discussing their applicability as well as limitations before presenting some recommendations for future research activities.<br
Keywords: elastohydrodynamic lubrication; non-dimensional groups; proximity equations; minimum film thickness; central film thickness; correction factors

Notwendigkeit für eine Methodenplattform zur Entwicklung von Produkten für nutzerspezifische Mobilitätsbedürfnisse - Krüger, Daniel; Eilmus, Sandra; Schmidt, Johanna (Design for X. Beiträge zum 22. DfX-Symposium, 2011)
UnivIS-Import:2015-04-16:Pub.2011.tech.FT.FT-KLMEFK.notwen

Novel approaches for the assembly simulation of rigid Skin Model Shapes in tolerance analysis - Schleich, Benjamin; Wartzack, Sandro (Computer-Aided Design, 2018)
While the modelling of nominal assemblies is sufficiently solved in modern computer-aided design tools, the assembly simulation for parts considering geometrical deviations is still an important research issue. Particularly in tolerance analysis, the assessment of the effects of geometrical part deviations on the part assembly behaviour is of central importance. Though established assembly simulation approaches for parts with geometrical deviations cover a moderate range of real assembly problems, they are not suitable for all assembly simulation problems. To overcome this shortcoming, a general framework and new approaches for the assembly simulation of Skin Model Shapes for the use in tolerance analysis are presented. The application of these assembly simulation approaches is highlighted in generalized case studies and recommendations for their use in tolerance simulations are derive
Keywords: Point-based models; Registration; Assembly simulation; Skin Model Shapes; Tolerance analysis

Numerical and Experimental Studies on Friction Reduction by Surface Modification in TEHL Contacts - Marian, Max; Weikert, Tim; Tremmel, Stephan (74th STLE Annual Meeting & Exhibition, 2019)
With the aim of improved energy efficiency of engine components, it is crucial to understand the underlying mechanisms of surface modification approaches, such as applying tribological coatings or microtextures. Within this contribution, TEHL simulations of the cam/tappet contact with modified surfaces are performed. Input data, like material and fluid parameters, geometries and load cases, are chosen according to the setup of a component test-rig, on which experimental tests are carried out to support the numerical findings. In particular, variants of amorphous carbon coatings and microtextures fabricated by laser ablation are investigated. Obtained insights indicate that coatings can reduce solid and fluid friction in all lubrication regimes. This corresponds to a shift of the Stribeck curve to the lower left. Conversely, microtexturing may reduce the fraction of solid friction while increasing fluid friction. This in turn resembles to a counterclockwise tilt of the Stribeck curv
Keywords: TEHL; Friction Mechanisms; Surface Modification

Numerical Investigations on Dimensional and Geometrical Deviations of Surface Textures in EHL Contacts - Marian, Max; Tremmel, Stephan; Wartzack, Sandro (International Tribology Conference Sendai 2019, 2019)
Micro-textures applied on rubbing surfaces of lubricated contacts have gained tremendous attention in the last two decades. Numerous experimental and numerical studies deal with the derivation and testing of advantageous micro-textures. Nevertheless, especially with respect to higher loaded elastohydrodynamically lubricated (EHL) rolling-sliding contacts, not all questions have been answered yet. Will texturing really provide as good effects as often claimed, and are there occasions when texturing could theoretically improve the tribological behavior but is questionable from other perspectives? For these reasons, transient 3D simulations of micro-textured EHL line- and point-contacts based on the full-system approach were performed, which act as a ‘numerical zoom’ into the contact area and contribute to a better understanding of local phenomena. For the hydrodynamics, a modified Reynolds equation was applied. Based upon the finite element method (FEM), the elastic deformation was computed for an equivalent body by applying the linear elasticity equation. Moreover, for example time-dependent squeeze effects, mixed lubrication, microhydrodynamics and cavitation were to be considered. Within this contribution, the effects of dimensional and geometrical deviations of discrete texture elements on lubricating conditions and thus friction and wear are addressed. This ranges from depth, length, width or flank angles of individual texture elements to the lateral distribution in and perpendicular to direction of sliding as well as the relative position of texture and contact area. It is shown that these deviations from nominal or optimized texture designs have a significant impact on the tribological performance, potentially overcompensating theoretical benefits. The findings emphasize the necessity for numerically derived optima and robust designs as well as manufacturing technologies with high precision to exploit the full potential of micro-texturin
Keywords: Micro-texturing; Dimensional Deviations; Geometrical Deviations; Elastohydrodynamic Lubrication

Numerical modeling of lubrication mechanisms in total knee replacements - Marian, Max; Rothammer, Benedict; Bartz, Marcel; Nečas, David; Vrbka, Martin; Wimmer, Markus A; Wartzack, Sandro (5th International Conference on BioTribology, 2021)
For an adequate design of total knee replacements (TKR), knowledge about stresses and lubrication conditions is vital. Within this study, a numerical model based upon the Finite Element Method and fully coupling the fluid’s hydrodynamics (generalized Reynolds equation) with the elastic deformation of the contacting bodies is presented. Thereby, realistic transient kinematics and loading conditions of the gait cycle (ISO 14243) were considered. For the numerical results, good agreement with experimental studies by means of a knee simulator with optical fluorescent measurement technique was achieved. Moreover, it was found that the complexity of numerical modeling has a strong effect on simulation results and thus on the prediction quality, especially for the fluid film height. The consideration of transient squeeze effects, non-Newtonian fluid characteristics, realistic geometries, transient kinematics and loading conditions is vital. The medial compartment was more heavily stressed and experienced higher pressures and smaller minimum film heights compared to the lateral condyle. The swing phase was determined by geometry and kinematics while load and geometry played a dominant role in the stance phase, where the overall lubricant gap was smaller. Generally, the reversal points of motion with zero entrainment speed largely affected the fluid film formation. Furthermore, the individual rheological synovial fluid parameters have a decisive influence on the lubricant film formation. Due to the wide variation between different patients, this can also lead to diverse tribological behavior ranging from full separation of the rubbing surfaces over the whole gait cycle to strong solid asperity contact and associated wear mechanisms.
Keywords: Total knee replacement; Synovial joint tribology; Soft-elastohydrodynamic lubrication; Finite Element Method

Numerical Modeling of Wear in a Thrust Roller Bearing under Mixed Elastohydrodynamic Lubrication - Winkler, Andreas; Marian, Max; Tremmel, Stephan; Wartzack, Sandro (Lubricants, 2020)
Increasing efforts to reduce frictional losses and the associated use of low-viscosity lubricants lead to machine elements being operated under mixed lubrication. Consequently, wear effects are also gaining relevance. Appropriate numerical modeling and predicting wear in a reliable manner offers new possibilities for identifying harmful operating conditions or for designing running-in procedures. However, most previous investigations focused on simplified model contacts and the wear behavior of application-oriented contacts is relatively underexplored. Therefore, the contribution of this paper was to provide a numerical procedure for studying the wear evolution in the mixed elastohydrodynamically lubricated (EHL) roller/raceway contact by coupling a finite element method (FEM)-based 3D EHL model with surface topography changes following a local Archard-type wear model, a Greenwood–Williamson-based load-sharing approach and the Sugimura surface adaption model. This study applied the operating conditions of an 81212 thrust roller bearing, considering realistic geometry and locally varying velocities. The calculated wear profiles in the raceway featured asymmetries, which were in good agreement with the experimental results reported in the literature and could be correlated with the velocity and slip distribution. In addition, the effects of speed, load and oil viscosity were investigated by means of four load cases and two lubricants, demonstrating the broad range of applying the numerical approach.<br
Keywords: multi-scale tribo-simulation; wear modeling; mixed lubrication; elastohydrodynamic lubrication; machine elements; thrust roller bearing

Numerical optimization of the roller face/rib geometry for friction reduction in tapered roller bearings - Wirsching, Sven; Marian, Max; Stahl, Thomas; Bartz, Marcel; Wartzack, Sandro (7th World Tribology Congress 2022, 2022)
In the context of increasing demands for energy efficiency of rolling bearings, secondary contacts are gaining relevance. This demands for an accurate and efficient numerical design of the contacting bodies while considering realistic geometries, movement and lubrication conditions. Within this contribution, the elastohydrodynamically lubricated roller face/ring rib contact of a tapered roller bearing with axial loading was therefore optimized using numerical elastohydrodynamic contact simulation, meta-modeling and evolutionary algorithms.<br

Numerical study on the lubrication in total knee replacements: The influence of dynamics, geometry, material and fluid - Marian, Max; Rothammer, Benedict; Bartz, Marcel; Nečas, David; Vrbka, Martin; Wimmer, Markus A; Wartzack, Sandro (7th World Tribology Congress, WTC 2022, 2022)
For an adequate design of total knee replacements, knowledge about stresses and lubrication conditions is vital. Within this study, a numerical model is presented and validated with experimental data. Good agreement between model predictions and experimental data as well as a strong influence of fluid, material and geometry assumptions as well as transient effects were found. It was demonstrated that the rheological synovial fluid properties have a decisive impact on the tribological behavio
Keywords: Total knee replacement; Synovial joint tribology; Soft-elastohydrodynamic lubrication; Finite Element Method

Numerical Wear Modeling in the Mixed and Boundary Lubrication Regime - Winkler, Andreas; Bartz, Marcel; Wartzack, Sandro (Lubricants, 2022)
The increasing use of low-viscosity lubricants in order to reduce the friction in machine elements such as rolling bearings is leading to increased operation in the mixed or boundary lubrication regime. The associated wear can lead to an earlier failure of tribological systems. In this context, a detailed wear simulation offers great potential with regard to the design of machine elements as well as the calculation of lifetimes. This contribution presents an approach for the numerical wear simulation of lubricated rolling/sliding-contacts. Therefore, a finite element method-based simulation model was developed which is able to deal with non-Gaussian surfaces and contacts subject to boundary and mixed lubrication. Using the example of an axial cylindrical roller bearing considering realistic geometry, locally varying velocities, and two load cases, the wear modeling results of the mixed and the boundary lubrication regime were illustrated. The wear coefficient required for Archard’s wear model was determined experimentally by means of a two-disc tribometer.<br
Keywords: wear modeling; contact mechanics; elastohydrodynamic lubrication; mixed lubrication; boundary lubrication; machine elements; thrust roller bearing; two-disc tribometer

Numerical Wear Simulation based on Experimentally Determined Wear Coefficients - Rothammer, Benedict; Winkler, Andreas; Bartz, Marcel; Wartzack, Sandro (65. Tribologie-Fachtagung. Reibung, Schmierung und Verschleiß. Forschung und praktische Anwendungen., 2024)
Es wird eine numerische Verschleißsimulation von misch- und grenzreibungsbehafteten tribologischen Kontakten vorgestellt. Anhand eines 2-Scheiben-Tribomters werden die für die Simulation erforderlichen Verschleißkoeffizienten experimentell ermittelt. Weiterhin werden am Beispiel zweier Wälzlager Simulationsergebnisse präsentiert und diskutiert.<br

Numerische Auslegung von Oberflächenmikrotexturen für geschmierte tribologische Kontakte - Marian, Max (FAU University Press, 2021)
Trotz einer Vielzahl an experimentellen und theoretischen Untersuchungen in der Literatur befindet sich der Ansatz der Oberflächenmikrotexturierung zur Steuerung von Reibung und Verschleiß in Tribo-Kontakten noch immer in der Trial-and-error-Phase. Ein ausbleibender Einzug in die industrielle Serienanwendung liegt insbesondere daran, dass der Einfluss auf das tribologische Verhalten und vorteilhafte Mikrotexturgeometrien und -anordnungen von der jeweiligen Kontaktart und den Betriebsbedingungen bedingt werden. Im Rahmen dieser Arbeit wurde daher eine Vorgehensweise zur Gestaltung von Oberflächenmikrotexturen erarbeitet. Den zentralen Kern bildeten dabei Simulationsmodelle zur numerischen Vorhersage des tribologischen Verhaltens von Mikrotexturen in geschmierten Kontakten basierend auf der Finite Elemente Methode. Die Möglichkeit zur maßgeschneiderten Auslegung der Mikrotexturgeometrie wurde durch ein Meta-Modell of Optimal Prognosis in Verbindung mit evolutionären Optimierungsalgorithmen geschaffen. Die Eignung und Validität wurde durch Anwendung für verschiedene hydrodynamische sowie harte und weiche elastohydrodynamische Kontakte von der Modell- bis hin zur Komponentenebene sowie durch begleitende experimentelle Untersuchungen aufgezeigt. Die Implementierung in kommerzieller Software sowie die Ableitung verallgemeinerter Gestaltungsrichtlinien erlauben zukünftig insbesondere die breite Nutzbarkeit durch Forschende und Entwicklungsingenieur*innen für verschiedene Anwendunge
Keywords: Tribologie; Hydrodynamik; Elastohydrodynamik; Reibung; Verschleiß; Oberflächenmikrotexturen

Numerische Simulation in der muskuloskelettalen Biomechanik - Kebbach, Märuan; Hucke, Lucie; Kluess, Daniel; Miehling, Jörg; Scherb, David; Wartzack, Sandro; Wechsler, Iris; Wittek, Andreas; Woiczinski, Matthias; Schwarze, Michael (Die Orthopädie, 2024)

Nutzerzentrierte Produktentwicklung durch systematische Integration von Marketingaspekten – ein erster Ansatz. - Kett, Susan; Schröppel, Tina; Wartzack, Sandro (25. DfX-Symposium Design for X., 2014)
The shift from seller’s to buyer’s markets in many different product divi-sions leads to a raising role of the user in product development processes. Especially implicit decision parameters such as comfort feeling need better consideration. This article suggests to consequently integrate models and tools from other disciplines, e.g. marketing, to generate competitive ad-vantages due to a better fulfillment of user’s needs. In those areas, focusing on users is much more established. As a starting point, a first glance of the topic is given by adapting Portfolio Models. The potential to directly link “soft” user decision parameters with product properties without any intermediates offers value to minimize misleading product development efforts. Further investigation in this area is recommended.
Keywords: product development; user integration; methodology; marketing

Oberflächen-Mikrostrukturierung in Wälzkontakten - Weschta, Martin; Pausch, Michael; Tremmel, Stephan; Wartzack, Sandro (Wissenschaftliches Kolloquium Wälzlager, 2013)

On Connected Tolerances in Statistical Tolerance-Cost-Optimization of Assemblies with Interrelated Dimension Chains - Heling, Björn; Aschenbrenner, Alexander; Walter, Michael; Wartzack, Sandro (14th CIRP CAT 2016 - CIRP Conference on Computer Aided Tolerancing, 2016)
Identifying a suitable compromise between tight and thus expensive tolerances and wide tolerances that may negatively influence the product quality is a major challenge. This paper focuses on the tolerance-cost-optimization of mechanical assemblies with interrelated dimension chains considering dependencies between the tolerance–cost-relationships. Taking into account interrelated dimension chains the crux is, however, that modifications of a single tolerance can influence several dimension chains as well as the resulting production costs. Based on different existing approaches for the statistical tolerance-costoptimization, the authors will provide appropriate guidance for the product developer dealing with interrelated dimension chains.
Keywords: tolerance allocation; interrelated tolerance-cost-function; connected dimension chains; modification of tolerance-cost-relation

On Friction Reduction by Surface Modifications in the TEHL Cam/Tappet‐Contact‐Experimental and Numerical Studies - Marian, Max; Weikert, Tim; Tremmel, Stephan (Coatings, 2019)
The overall energy efficiency of machine elements and engine components could be improved by using new technologies such as surface modifications. In the literature, surface engineering approaches like microtexturing and the application of diamond-like carbon (DLC) coatings were frequently studied separately, with focus on a specific model contact and lubrication conditions. The contribution of the current study is to elucidate and compare the underlying friction reduction mechanisms of the aforementioned surface modifications in an applicationorientated manner. The study applied the operating conditions of the thermoelastohydrodynamically lubricated (TEHL) cam/tappetcontact of the valve train. Therefore, tribological cam/bucket tappet component Stribeck tests were used to determine the friction behavior of ultrashort pulse laser fabricated microtextures and PVD/PECVD deposited silicondoped amorphous carbon coatings. Moreover, advanced surface characterization methods, as well as numerical TEHL tribosimulations, were utilized to explore the mechanisms responsible for the observed tribological effects. The results showed that the DLCcoating could reduce the solid and fluid friction force in a wide range of lubrication regimes. Conversely, microtexturing may reduce solid friction while increasing the fraction of fluid friction.<br
Keywords: thermoelastohydrodynamic lubrication; DLCcoating; microtexturing; surface modification; friction mechanisms; energy efficiency; internal combustion engine; cam/tappetcontact

On Lubrication Mechanisms in Total Knee Replacements - Marian, Max; Orgeldinger, Christian; Rothammer, Benedict; Bartz, Marcel; Tremmel, Stephan; Wartzack, Sandro (62. Tribologie-Fachtagung. Reibung, Schmierung und Verschleiß. Forschung und praktische Anwendungen., 2021)
The longevity of total knee arthroplasty (TKA) is considerably affected by the overall biotribological performance and synovial fluid lubrication phenomena. The present study is therefore targeted to identify lubrication mechanisms occurring in TKAs, focusing on the role of synovial fluid propertie
Keywords: Total knee replacement; synovial joint tribology; soft-elastohydrodynamic lubrication; synovial fluid

On Simulation Knowledge Acquisition Using Gaussian Processes for the Design of Electric Motors - Dworschak, Fabian; Tüchsen, Johann; Pinto, Diogo; Pop, Adrian-Cornel; Schleich, Benjamin; Wartzack, Sandro (Procedia CIRP Volume 84, 2019)
In the automotive industry, high efforts are made to design high-efficiency, low-cost, requirement-optimized electric drives. Traditionally, time-consuming and expensive 3D finite element analyses are used to assess the effects of different design parameters from various engineering disciplines such as the electromagnetics, heat transfer, and mechanics. Often, to decrease the calculation efforts, scalable, physics-based reduced order models are used. For setting up and interpreting such reduced order models, simulation experts employ implicit knowledge by applying heuristic correction factors. This paper proposes a novel method to formalizing such implicit simulation knowledge using Gaussian Processes. Furthermore, the successful application of the method to a case study of electric motors is reported by validating the aforementioned correction factors for different motor designs.<br
Keywords: Knowledge Acquisition; Meta-Modelling; Gaussian Process; Electric Motor; Case Study

On the impact of geometric deviations on structural performance - Schleich, Benjamin; Stockinger, Andreas; Wartzack, Sandro (Proceedings of the 12th CIRP Conference on Computer Aided Tolerancing, 2012)
Geometric deviations are observed on nearly every manufactured part since manufacturing processes are inherently imprecise and measuring processes always involve uncertainties. Therefore, tolerances have to be set. They define the allowable geometric deviations of a part. However, geometric deviations have an influence on the structural performance of the parts also. In other words, there are interdependencies between geometric deviations and deformations which affect the dimensional accuracy of a loaded part in an assembly. Therefore, this paper proposes an approach to determine the impact of geometric deviations on the structural performance of a part. This method can be used in terms of sensitivity analysis, analysis of robustness and evaluation of reliability. It can be concluded that geometric deviations can have a big impact on the structural performance and thus not only parametric deviations but also geometric deviations regarding the shape of a part itself should be taken into account within the structural performance analysis.
UnivIS-Import:2015-04-16:Pub.2012.tech.FT.FT-KLMEFK.onthei
Keywords: stochastic finite elements; random fields; computer aided tolerancing; sensitivity analysis; structural performance

On the Influence of Fatigue Damage in Short-Fibre Reinforced Thermoplastic PBT GF30 on Its Residual Strength under High Strain Rates: An Approach towards Simulative Prediction - Witzgall, Christian; Steck, Patrick; Wartzack, Sandro (Journal of Composites Science, 2023)
Only by using accurate material data can precise simulation results be achieved. This principle also and especially applies in the field of crash simulation. However, in the simulation of short-fibre reinforced thermoplastics, material parameters are usually used that originate from the material testing of as-new samples. In order to get closer to the condition on the roads, where not only new vehicles are driving, the influence of service loads on the crashworthiness has to be investigated. This paper reports on studies of PBT GF30, a polybutylene terephthalate reinforced with 30% glass fibres, in which fatigue damage was induced in the material by cyclic loading. The residual strength was then determined in a high-speed experiment and compared with the strength of virgin samples. In order to enable the usability of the findings in the simulation, a modified failure criterion was implemented that takes the previous fatigue damage into account. The prediction quality of the simulation model was compared with the experimental findings and it can be concluded that there is good agreement.<br

On the Influence of Incorrect Idealized Joint Axes to the Design Process of Orthoses - Steck, Patrick; Scherb, David; Miehling, Jörg; Wartzack, Sandro (Computer Methods in Biomechanics and Biomedical Engineering II, 2024)
According to the analysis of the Global Burden of Disease (GBD) approximately 1.71 billion people worldwide suffer from musculoskeletal disorders. For the treatment of gait pathologies ankle foot orthoses (AFO) are used in the field of rehabilitation and physiotherapy. However, conventional AFOs are pre-terminated to fit a wide range of user groups. For the development of a real patient-centered AFO precise information about the individual joint axes position and orientation for each patient are necessary. This contribution illustrates the great influence of idealized joint axis, which are commonly used in generic skeleton systems in musculoskeletal simulation software for the prediction of ankle forces. For the testmodel it is shown, that the idealized ankle joint axis differ 21% regarding the resulting joint forces in comparison to the real axis. Furthermore, it is shown that 3D scanning methods can provide similarly good results in the determination of joint axes like high-cost (magnetic resonance) or radiation-risk (computed tomography) methods.<br
Keywords: ankle foot orthosis; lightweight design; user-centered design; concept design

On the Potential of Slicing Algorithms in Additive Manufacturing for the Optimization of Geometrical Part Accuracy - Schächtl, Paul; Schleich, Benjamin; Wartzack, Sandro (Procedia CIRP, 2022)
Despite its potentials, geometrical inaccuracies remain a major shortcoming for Additive Manufacturing in general and especially for Fused Layer Modeling, even though much research effort is put in enhancing mechanical properties and reducing process-specific deviations by optimizing process parameters. Novel slicing and path planning algorithms, such as non-planar printing, are suitable tools for addressing these problems and thus for improving geometrical part accuracy, but are subject of current research and only partly applicable. With the aim to show and evaluate the potential of these algorithms in the context of tolerancing, this paper proposes an approach for applying one pre-processing technique to 3D-printed parts. The exemplary application shows the applicability and the high potential of advanced slicing and path planning algorithms. The findings therefore indicate that aspects of pre-processing should be matched with the parts geometry and therefore have to be frontloaded into the product and the tolerance design for their consideration.<br

On the Selection of Sensitivity Analysis Methods in the Context of Tolerance Management - Heling, Björn; Oberleiter, Thomas; Schleich, Benjamin; Willner, Kai; Wartzack, Sandro (Journal of Verification, Validation and Uncertainty Quantification, 2019)

On the Simulation of the Micro-Contact of Rough Surfaces Using the Example of Wet Friction Clutch Materials - Voelkel, Katharina; Rothemund, Markus; Garibello, Sebastian Albarracin; Kramer, Vincent; Pflaum, Hermann; Stahl, Karsten (Lubricants, 2019)
Friction behavior in a sliding contact is strongly influenced by the surface topography of the bodies in contact. This also applies to friction clutches. Even small differences in surface topography may cause significant differences in friction behavior. Thus, it is important to be able to characterize the micro-contact of the rough sliding surfaces, which are, in the case of a clutch, steel plate and friction material. One important measure for the characterization of the micro-contact is the real area of contact. Another important aspect is the contact pattern. The article introduces a method to implement a FEM (Finite Element Method) model from real surface measurements. Real surface topography of the friction pairing is considered. The simulation method is applied to different friction pairings and operating conditions. Computational results with rough and smooth steel plates, new and run-in friction linings, and different nominal surface pressure verify the model. In addition, the results on real area of contact between a steel and a friction plate are compared with published values.
CRIS-Team WoS Importer:2019-06-28

On the transferability of nominal surrogate models to uncertainty consideration of clinch joint characteristics - Bode, Christoph; Götz, Stefan; Wartzack, Sandro (Procedia CIRP, 2024)
The mechanical joining process clinching is becoming increasingly important, especially for multi-material car body elements enabling lightweight design. However, the design of these joining points is usually based on expert knowledge and time-consuming experiments. For this reason, simulations are used in combination with surrogate models to predict the characteristics of clinch points for specific process parameters. Thereby, the process parameters are assumed to be ideal, so that inherent uncertainties are currently neglected. In order to overcome this deficiency and ensure a realistic prediction of clinch point characteristics, a consideration of variations is inevitable. Therefore, this paper analyses the transferability or significance of the nominally predicted values of existing surrogate models for clinch joints, taking into account process parameters with unavoidable variations. This shows, that the nominal parameter configuration affects the scattering of joint characteristics when considering variations. Moreover, implications for the necessary additional sampling in order to increase the significance of existing (nominal) surrogate model predictions are given, while considering the additional computational effort involved.
CRIS-Team Scopus Importer:2024-11-29
Keywords: Clinching; Sampling; Simulation; Surrogate modeling; Uncertainty

On the Transient Effects at the Beginning of 3D Elastic-Plastic Rolling Contacts for a Circular Point Contact Considering Isotropic Hardening - Jüttner, Michael; Bartz, Marcel; Tremmel, Stephan; Wartzack, Sandro (Lubricants, 2022)
In a three-dimensional transient simulation of the elastic–plastic rolling contact, transient effects can be observed at the beginning of the rolling until a stationary state is reached after rolling for a length of several times the contact radius. In most cases, the steady-state regime is in focus of scientific investigations, whereas the transient effects are hardly considered. In the present work, those transient effects at the beginning of a frictionless rolling contact of a rigid sphere on an elastic–plastic plane are studied in detail. The analysis is limited to isotropic strain hardening. In particular, the changes of the contact pressure during rolling, as well as the plastic strain state and plastic deformations remaining after rolling are investigated. This is intended to get to the bottom of existing explanatory approaches from literature, which are based on the change in conformity. Beyond that, a more profound explanation of the transient effects is developed by identifying existing correlations.
Keywords: rolling contact; elastic-plastic; transient simulation; semi-analytical method; transient effects

Ontologie-basierte Tolerierung von Produktkonzepten - Meixner, Matthias; Götz, Stefan (Summer School Toleranzmanagement - Beiträge zur 4. Summer School - September 2020, 2020)

Ontology-based approach for the provision of simulation knowledge acquired by Data and Text Mining processes - Kestel, Philipp; Kügler, Patricia; Zirngibl, Christoph; Schleich, Benjamin; Wartzack, Sandro (Advanced Engineering Informatics, 2019)
Numerical simulation techniques such as Finite Element Analyses are essential in today's engineering design practices. However, comprehensive knowledge is required for the setup of reliable simulations to verify strength and further product properties. Due to limited capacities, design-accompanying simulations are performed too rarely by experienced simulation engineers. Therefore, product models are not sufficiently verified or the simulations lead to wrong design decisions, if they are applied by less experienced users. This results in belated redesigns of already detailed product models and to highly cost- and time-intensive iterations in product development. Thus, in order to support less experienced simulation users in setting up reliable Finite Element Analyses, a novel ontology-based approach is presented. The knowledge management tools developed on the basis of this approach allow an automated acquisition and target-oriented provision of necessary simulation knowledge. This knowledge is acquired from existing simulation models and text-based documentations from previous product developments by Text and Data Mining. By offering support to less experienced simulation users, the presented approach may finally lead to a more efficient and extensive application of reliable FEA in product developmen
Keywords: Knowledge-based engineering; Simulation; Finite Element Analysis; Ontology-based knowledge representation; Text Mining; Data Mining

Ontology-based approach for the use of Intentional Forgetting in product development - Kügler, Patricia; Kestel, Philipp; Schon, Claudia; Marian, Max; Schleich, Benjamin; Staab, Steffen; Wartzack, Sandro (DESIGN 2018 - 15th International Design Conference, 2018)
When reusing product knowledge in design processes, developers have to decide which knowledge elements are relevant for a task. Thus, mechanisms of knowledge removal are vital for a successful reuse, but are not yet assisted by procedure models. This contribution introduces Intentional Forgetting as a methodology of intelligent removal processes in ontological knowledge bases. The aim is to support developers by providing relevant contents for reuse systematically. The development process of a testrig, that is highly based on knowledge reuse, is considered as use case.<br
Keywords: intentional forgetting; ontology; knowledge based engineering (KBE); data driven design

Ontology-based knowledge provision for decision support in product development - Pickel, Jessica; Gerschütz, Benjamin; Horber, Dennis; Götz, Stefan; Wartzack, Sandro (Proceedings of the 34th Symposium Design for X (DFX2023), 2023)
The product development process confronts engineers with numerous decision problems. In this context, it is a challenge to consider all underlying heterogeneous data sources and decision methods to avoid incorrect decisions. Regarding these issues, ontologies offer the possibility to represent knowledge in a structured and adaptable way. Thus, this contribution proposes a methodical conception of a product development ontology and a novel approach to support developers in solving interrelated decision problems by providing relevant knowledge in a target-oriented way. In addition, the application is demonstrated by an exemplary development scenario for the axle design of a micromobility solutio
Keywords: Ontology; product development process; decision-making; requirements management; knowledge management

Ontology based modelling of the development process for the deduction of a property validation planning - Wartzack, Sandro; Westphal, Christoph (4. Grazer Symposium Virtuelles Fahrzeug, 2011)
UnivIS-Import:2015-04-16:Pub.2011.tech.FT.FT-KLMEFK.ontolo

Ontology-based representation of tolerancing and design knowledge for an automated tolerance specification of product concepts - Götz, Stefan; Schleich, Benjamin (Procedia CIRP, 2020)
Motivated by the high importance of the tolerance specification, numerous partially automated approaches have emerged. However, since these approaches require an extensive geometry definition, they are not applicable for an early definition of the tolerance concept and its evaluation by Robust Design aspects. Motivated by this lack, this paper presents a novel ontology-based approach combining knowledge from the product design and tolerancing domains to enable an automated tolerance specification of product concepts. This close linkage enables a more precise specification and bridges the gap to the subsequent final specification in accordance with current GPS standards. Finally, this novel approach is demonstrated by means of a crank drive mechanism.<br
Keywords: Robust Design; Tolerance Specification; Ontology

On uncertainties in simulations in engineering design: A statistical tolerance analysis application - Walter, Michael; Wartzack, Sandro; Storch, Markus (Journal of Simulation, 2014)
Simulations not only facilitate new and unprecedented insights in highly sophisticated science areas, but also support product design in engineering in terms of improved functionality, cost and time issues. However, as a matter of fact, simulations examine limited excerpts of real systems with accompanying simplifications, abstractions and idealizations. Hence, there is a distinct need to be aware of upcoming risks in simulation outcomes caused by uncertainties. These influence every step of forward-thinking simulation design which is not only restrained by modeling practice but begins with reality perception itself.The intention of the paper is to embed an awareness of uncertainty in the context of simulation by linking major classes of uncertainty with uncertainties within simulations in engineering design. Besides the decisive inclusion of reality as the starting point, mathematic approaches are also used to understand how those uncertainty classes evolve through exponential knowledge creation of systems. The transfer to statistical tolerance analysis shall finally put emphasis on the practical classification of uncertainty, starting from data preparation via concept design and mathematical implementation to result depiction. In the end, the reader's conception of possible uncertainties in special simulation cases shall be sharpened which, vice versa, shall lead to even better and well-thought-out simulation outcomes. © 2014 The Society for Modeling and Simulation International.
UnivIS-Import:2015-03-09:Pub.2014.tech.FT.FT-KLMEFK.onunce
Keywords: statistical tolerance simulation; tolerance analysis; tolerance management; Uncertainties in simulation

Operation-oriented One-piece-flow Manufacturing: Autonomous and Smart Systems as Enabler for a Full-meshed Production Network - Scholz, Michael; Kolb, Saskia; Kästle, Christopher; Franke, Jörg (49th CIRP Conference on Manufacturing Systems, CIRP-CMS 2016, 2016)
Due to the effects of mass-customization there is an increase of the variance of products combined with a reduction of the number of units per variation. Therefore, it is necessary that the next generations of production lines, especially the assembling devices, have to be designed more adaptable. Regarding business information systems this trend is realized by an increasing digital integration of the particular units. Especially, for mass production the so called "line concept" is well established. This inflexibility of the physical material flow blocks the spread of mass-customization into established industrial sectors where linked manufacturing steps are commonly used. In a flow-orientated value stream with physically linked production units it is not possible to produce individualized products without additional expenses. Therefore, it is necessary to resolve the physically linked material flow equal to the digital integration of the units. This will lead to a physically and digitally full-meshed production site. The enabler is an autonomous navigating and smart transport system for a physical integration of the production units. Especially for the production of goods with a high variant diversity the benefits of a physically meshed production site are obviously. Each part gets his own and individual routing, which depends on the current machine availability and the setting of each machine. Furthermore, this approach creates a new degree of freedom for production site planning. The placement of the machines has not to be flow-oriented due to the individual and flexible connection by autonomous and self-navigating transport entities. Thereby, the advantages of a flow-oriented mass-production can be combined with those of a job-shop production.
Keywords: autonomous tranport system; manufacturing concept; operation-oriented one-piece-flow

Optimal control simulation predicts effects of midsole materials on energy cost of running - Dorschky, Eva; Krüger, Daniel; Kurfess, Nicolai; Schlarb, Heiko; Wartzack, Sandro; Eskofier, Björn; van den Bogert, Antonie J. (Computer Methods in Biomechanics and Biomedical Engineering, 2019)
Testing sports equipment with athletes is costly, time-consuming, hazardous and sometimes impracticable. We propose a method for virtual testing of running shoes and predict how mid- soles made of BOOSTTM affect energy cost of running. We contribute a visco-elastic contact model and identified model parameters based on load-displacement measurements. We pro- pose a virtual study using optimal control simulation of musculoskeletal models. The predicted reduction in energy cost of 1% for BOOSTTM in comparison to conventional materials is consistent with experimental studies. This indicates that the proposed method is capable of replacing experimental studies in the futur
Keywords: Virtual design; footwear; running; musculoskeletal simulation

Optimierung der tribologischen Effizienz von Lagerkomponenten mit modifizierten ta-C Beschichtungen - Polzer, Markus; Bartz, Marcel; Schulz, Edgar; Procelewska, Joanna; Wartzack, Sandro (Tribologie-Fachtagung, 2022)
Tetraedrisch amorphe Kohlenstoffschichten (ta-C-Schichten) werden bereits als reibungsreduzierende, verschleißbeständige Funktionsschichten auf tribologisch beanspruchten Komponenten genutzt. Jedoch stellen die gekrümmten und tribologisch hochbeanspruchten Oberflächen von Lagerkomponenten eine große Herausforderung dar, zumal diese zu deutlich erhöhten Eigenspannungen der ta-C Schichten und somit vorzeitiger Schichtdelamination beitragen. Insbesondere in geschmierten Systemen kann es während tribologischer Beanspruchung zu komplexen Wechselwirkungen zwischen Schichtsystem und Schmierstoffadditiven im tribologischen Kontakt (Tribokontakt) kommen. Dies kann zu unerwünschten Beeinträchtigungen der Lebensdauer und der Effizienz des vorliegenden tribologischen Systems führen. Die alleinige Betrachtung der Dotierungselemente und der mechanischen Eigenschaften der Schichten reichen nicht aus, um derartige Beeinträchtigungen prognostizieren zu können. Um dieses komplexe Verhalten besser verstehen und um weitere effizienz- und lebensdauersteigernde Effekte zu ableiten zu können, soll in diesem Beitrag der Einfluss unterschiedlicher Dotierungselemente im geschmierten Tribokontakt untersucht werden. Dafür werden, neben der Analyse der mechanischen Eigenschaften und Topologie, verschiedene dotierte ta-C-Schichtsysteme mit einer undotierten ta-C-Schicht verglichen. Die beschichteten Proben wurden gegenüber unbeschichteten 100Cr6 in verschiedenen Reibungs- und Verschleißprüfständen getestet. Als Schmierstoffe kamen ein vollformuliertes PKW-Öl auf PAO Basis einmal ohne und einmal mit molybdänhaltigen Additiven zum Einsatz. Die Ziele dieser Untersuchungen sind die Auswirkungen der Dotierungselemente auf das Reibungs- und Verschleißverhalten zu bestimmen, die in den Versuchen auf der Kontaktfläche auftretenden Mechanismen darzustellen und mögliche Wechselwirkungen im Tribokontakt abzuleiten. <

Optimization of Build Time and Support Material Quantity for the Additive Manufacturing of Non-Assembly Mechanisms - Hallmann, Martin; Götz, Stefan; Schleich, Benjamin; Wartzack, Sandro (Procedia CIRP Volume 84, 2019)
In the context of modern industrial manufacturing, Additive Manufacturing processes are gaining more and more importance. Thus, the required quantity of material as well as the production time, which is mainly influenced by the build time required for the layerwise manufacturing process, are decisive for a successful industrial application. At component level, various approaches for minimizing the build time and the quantity of material are discussed in literature and are yet implemented in commercial software tools for preprocessing, the so-called slicing software. However, there is a lack of suitable methods for expediting the manufacturing process of non-assembly mechanisms. Although the positions and orientations of the individual, mutually movable linkages of a mechanism, which are defined in the CAD model, have a significant influence on the resulting build time and quantity of support material, the optimization potential has remained untapped so far. Motivated by this shortcoming, the paper introduces a method for achieving minimum build time and support material quantity using a meta-heuristic optimization technique. By integrating a suitable slicing software in the optimization process, the analysis of build time and support material quantity is based on the machine code, which is adapted to the applied machine and its various settings of the process parameters. The novelty of the contribution can be found in the optimization of build time and support material quantity for the additive manufacturing of non-assembly mechanisms by determining an optimal positioning of the individual movable links for the manufacturing process. A parallel 3RRR mechanism serves as a case study to show the benefits and the applicablity of the proposed method.
Keywords: Optimization; Additive Manufacturing; Non-assembly mechanisms; Build time analysis

Optimizing the individual design of revision hip implants – evaluating the effects for bone and stem using patient-specific finite element models - Scherb, David; Barbosa, Maria Helena; Völkl, Harald; Fleischmann, Christopher; Betsch, Marcel; Sesselmann, Stefan; Wartzack, Sandro; Miehling, Jörg (Proceedings of the 35th Symposium Design for X (DFX2024), 2024)

PADDME—Process Analysis for Digital Development in Mechanical Engineering - Gerschütz, Benjamin; Consten, Yvonne; Götz, Stefan; Wartzack, Sandro (Processes, 2024)
Design processes are always in motion, since more and more data-driven methods are used for various design and validation tasks. However, small and medium enterprises especially struggle with enhancing their processes with data-driven methods due to a lack of practical and easy-to-use analysis and redesign methods which can handle design process characteristics. In this paper, we present PADDME, which stands for process analysis for digital development in mechanical engineering, as a novel method that, in contrast to currently available analysis methods, considers those design process characteristics with respect to the integration of data-driven methods. Furthermore, a novel technology-readiness framework for digital engineering is introduced. Using the PADDME method, an industrial case study on introducing data-driven methods into the design and evaluation process chain is presented. The usability and novelty of the method are shown by the case study. Thus, PADDME allows a detailed capturing of current design processes and paves the way for process optimisation through data-driven methods. PADDME is a valuable method for advancing digital mechanical engineering processes in small and medium enterprises, and future work will focus on refining and expanding its application and evaluation.<br
Keywords: digital engineering; design process; business process management; process evaluation; digitalisation; data-driven method

Parametric Movement Synthesis: Towards virtual Optimisation of Man-Machine Interaction in Engineering Design - Wolf, Alexander; Wartzack, Sandro (Proceedings of the DESIGN 2018 15th International Design Conference, 2018)
A parametric movement synthesis approach is introduced, which allows the adaptation of a synthesized movement to a specific use case by varying geometrical parameters. This parametric movement synthesis empowers the product developer to optimize products purely virtually in terms of ergonomics and (dis-)comfort by using musculoskeletal simulation. We developed such a parametric model for a lifting movement to analyse several scenarios. The results of the analyses show to what extent this procedure may support the product developer to improve the man-machine interaction of products.<br
Keywords: human centred design; musculoskeletal simulation; movement synthesis; ergonomics; design for x (DfX)

Parametrische biomechanische Simulation am Beispiel des Radfahrens - Miehling, Jörg; Wartzack, Sandro (Beiträge zum 25. DfX-Symposium, 2014)
Shrinking product lifecycles and consequently shorter development times demand a decreasing number of iterations as well as physical prototypes to be manufactured. An efficient implementation of the virtual product development paradigm can contribute to achieve these objectives. As product designers do not need general design guidelines, but specific recommendations on how to design products, especially the field of user-centred design holds high potential for the virtual prediction and optimisation of user-product interactions. This contribution features the parametric biomechanical simulation of cycling creating an approach to directly compare design alternatives based on the inner strain condition of the human musculoskeletal system considering the given external boundary conditions.
Keywords: biomechanics; virtual product development; digital human modelling; parametric simulation

Passive Ankle-Foot Orthoses: A Novel Approach for Passive Support of Plantar and Dorsiflexion Based on an Innovative Mechanism and Closed-Loop Logic - Steck, Patrick; Scherb, David; Miehling, Jörg; Wartzack, Sandro (Volume 1: Acoustics, Vibration, and Phononics; Advanced Design and Information Technologies, 2024)
The shifting demographics worldwide signal a looming challenge: an increasingly aging population. Along with this demographic shift comes an increase in age-related health issues, with neurological conditions like strokes being especially prominent. Patients who suffering on such diseases often have a so-called plantar and dorsal weakness, i.e. a reduction in lifting and lowering the foot during gait. An established treatment method is the use of so-called ankle foot orthoses (AFO). While active AFOs offer dynamic support through external energy sources, passive AFOs are more reliable because of the use of their inherent stiffness and the energy provided by the wearer itself. Despite their potential benefits, current passive AFOs predominantly focus on supporting dorsiflexion. Research into the passively support of plantar flexion is still at the beginning and is now to be significantly expanded by the innovative mechanism presented in this article. The mechanism uses torsion springs that harvest energy during specific gait phases and release it when it comes to a trigger moment during the gait cycles. This energy harvesting and supplying were simulatively tested with multi body simulation. The simulations of the mechanism showed support of the ankle moment by 58% (79 Nm) for a test subject with 50% muscle weakening (50 N m) and an average gait speed of 1.4 m s−
Keywords: orthotics; ankle foot orthoses; passive orthoses; lightweight design; user-centered design

Patientenspezifische Modellierung des passiven Bewegungsapparates als Grundlage für die präoperative Abschätzung postoperativer Folgeerscheinungen des endoprothetischen Hüftgelenkersatzes - Scherb, David; Kurz, Marlene; Fleischmann, Christopher; Wolf, Alexander; Sesselmann, Stefan; Miehling, Jörg; Wartzack, Sandro (Proceedings of the 31st Symposium Design for X (DFX2020), 2020)
During preoperative planning of total hip arthroplasty, the patients’ biomechanics is widely reduced to geometrical parameters. To provide the orthopedist more functional biomechanical parameters, a method is shown to model a patient-specific musculoskeletal human model via CT-/MRI-images in OpenSim. Main focus of this contribution is the setup of the passive musculoskeletal system. A generic human model and a segmented dataset of bones from the hip area serve as the basis for the modelling process. During the method the generic model is processed by scaling it to the anthropometry of the patient and adjusting subject-specific kinematics and shapes gathered from the segmented data. Finally, to reach the patient-specific representation the segmented bones are integrated into the mode
Keywords: Patient-specific modeling; Image-based model; Musculoskeletal human model; OpenSim; Total Hip Arthroplasty

Patient-Specific Modelling for Preoperative Estimation of Hip Mechanics for Improved Planning of Total Hip Endoprosthesis Using Multibody Simulations - Leher, Irina; Fleischmann, Christopher; Scherb, David; Kollerer, Marius; Miehling, Jörg; Wartzack, Sandro; Sesselmann, Stefan (International Conference on Emerging Technologies and Future Systems V, 2021)
The increasing number of total hip arthroplasty and the demographic change lead to a rise in the number of revision surgeries. Implementation of musculoskeletal models in surgical planning could improve quality of life after revision surgery, due to the consideration of the individual patient’s biomechanical conditions. In multibody simulation, a distinction is made in the degree of individualization between the anthropometric and patient-specific scaling of musculoskeletal models. In this study, the differences in moment arm length, hip joint reaction force, muscle activation and forces between these two musculoskeletal models were analyzed. Due to high influences of individualized anatomical parameters on simulation results, it is recommended to consider patient-specific biomechanics for future total hip arthroplasty planning.
Keywords: Biomechanics; Magnetic resonance imaging; Maximum isometric force; Muscle segmentation; Musculoskeletal model; OpenSim; Orthopaedics; Patient-specific modelling; Total hip arthroplasty

Phasenübergreifende Unterstützung der Elektromotorenentwicklung mittels eines Assistenzsystems - Tüchsen, Johann; Schleich, Benjamin; Wartzack, Sandro (Konstruktion, 2021)
Im Zuge der Elektrifizierung des Automobils muss, neben dem Traktionsantrieb, eine große Vielfalt an kleineren Elektromotoren innerhalb kurzer Zeit vom Elektromotorenhersteller angeboten und entwickelt werden. Dieser Problemstellung wird in diesem Beitrag mit einem wissensbasierten Assistenzsystem begegnet, das die Entwicklung von den Anforderungen bis hin zum fertigen Motor phasenübergreifend unterstützt. Dabei wird das modulare, web-basierte Konzept vorgestellt und anschließend seine Anwendung exemplarisch erläutert. Das beim Fallgeber eingesetzte System führt dabei zu einer höheren Transparenz durch standardisierte Dokumentationen und einer fehlerreduzierten und effizienteren Auslegung.

Pinch Valve Approach for a Biofilm Resistant Mechatronic Intraurethral Artificial Urinary Sphincter* - Preis, Alexander; Grigull, Ronja-Celine; Wang, Yacheng; Benke, Elisabeth; Martin, Sina; Rieker, Ralf; Franke, Jörg; Reitelshöfer, Sebastian (2023 45th Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC), 2023)
Stress urinary incontinence is the involuntary leakage of urine during increased abdominal pressure, such as coughing, sneezing, laughing, or exercising. It can have a significant negative impact on a person's quality of life and can result in decreased physical activity and social isolation. The presented closure mechanism for a mechatronic intraurethral artificial urinary sphincter is designed to be inserted minimally invasive into the urethra. The device consists of a solid shell, which serves as a housing for the electronics and is designed to enable fixation in the urethra. During micturition, the urine flows through the system, where it is guided through an elastic silicone-tube that, on the one hand, enables closure by a squeezing mechanism and, on the other hand, prevents biofilm growth by oscillation at a frequency of 22.5 Hz. The squeezing mechanism consists of a pinch valve system actuated by a piezo motor. The system has been tested under urodynamic conditions and the results show that it is able to close the urethra effectively to restore continence. The device is able to withstand sudden loads and shows good performance in terms of biofilm prevention during first experiments with artificial urine. The results show that the mechatronic intraurethral artificial urinary sphincter has the potential to be an effective and minimally invasive alternative to current treatment options for stress urinary incontinence.Clinical Relevance— This novel concept of a mechatronic intraurethral artificial urinary sphincter presents a promising alternative treatment option for patients suffering from stress urinary incontinence. As it is designed to be inserted minimally invasive, it reduces the impact and complications associated with current treatment options. The future development and testing of the device could lead to a safe and effective option for clinicians to offer their patients with stress urinary incontinence, which can improve their quality of life, and decrease costs for society and healthcare systems.<br

Plenary talk: "Nowear to be found" - Neusser, Kevin; Rothammer, Benedict (7th YOUNG TRIBOLOGICAL RESEARCHER SYMPOSIUM, 2024)

POSEIDON – Entwicklung reibungsarmer Kohlenstoffschichtsysteme für den Einsatz unter tribokorrosiven Betriebsbedingungen - Hasselbruch, Henning; Decho, Helge; Kröner, Julia; Bartz, Marcel; Mehner, Andreas (63. Tribologie-Fachtagung 2022. Reibung, Schmierung und Verschleiß. Forschung und praktische Anwendungen., 2022)
The sea with its tides offers great potential for technical applications for energy generation. Due to the high salinity, rolling and plain bearings made of conventional bearings steels (e. g. 100Cr6) are usually used under corrosionprotective lubricant conditions and require a hermetic encapsulation that prevents the contact with lquid (acqueous) ambient media. The result is an energy lost of about 30 % due to incresed friction in the encapsulated system. Sealless bearings would therefore significantly increase the overall efficiency of the bearings. However, a seal-less design of the rolling bearings requires new solution strategies that ensure the longest possible service life under harsh tribocorrosive operating conditions. One promising and ressource-saving approach is the deposition of hydrogenated amorphous carbon coatings (a-C:H) using the reactive magnetron sputtering technology in order to protect the bearings from wear and corrosion. As part of the BMWK-funded research project POSEIDON I and II, a-C:H coatings with high wear and corrosion resistance and low coatings defect densities are developed. The influences of relevant PVD process parameters, individual coating thicknesses and various doping elements of the interlayers and fuctional layers on the achievable mechanical, morphological and tribological coating properties are experimentally investigated. In particular, silicon-doped a-C:H coatings (a-C:H:Si) with Cr/CrNx interlayers show promising application potential with regard to adhesion strength, hardness, tribological properties and corrosion resistance. <br

Potentialanalyse SysML-basierter Modellierungen von Systemen und Prozessen im Kontext des Toleranzmanagements - Schleifer, Simon (Tag des Systems Engineering 2023, 2023)
Das Toleranzmanagement umfasst eine Vielzahl an Aktivitäten im Produktentstehungsprozess, woraus eine Reihe unterschiedlicher System- und Prozessmodellierungen resultiert. Dadurch wird die geschlossene Systemmodellierung erschwert, da keine einheitliche Modellierungssprache etabliert ist. Das Model-Based Systems Engineering, insbesondere die Verwendung der Modellierungssprache Systems Modeling Language (SysML) kann auf Grund des formalen Charakters hierfür eine Lösung bieten. Zur Potentialbewertung SysML-basierter Modellierungen von Systemen und Prozessen im Kontext des Toleranzmanagements wird ein kombiniertes Systemmodell aus diversen Modellierungsansätzen aus der Forschung vorgestellt. Diese wurden über eine Literaturrecherche identifiziert. Der Fokus des Systemmodells liegt auf der Beschreibung des Toleranzkonzeptes und einfachen Geometrien sowie der dynamischen Erweiterung um weitere Aktivitäten. Dafür kommt die zweite Version der SysML zum Einsatz. Darüber hinaus wird die Nutzbarmachung des erstellten Systemmodells über einen Python-Client gezeigt. Dieser unterstützt die automatische Erstellung eines 3D-Modells basierend auf dem Systemmodell sowie die Rückführung von Änderungen.<br
Keywords: Toleranzmanagement; Model-Based Systems Engineering (MBSE); Systems Modeling Language (SysML)

Potential beschichteter Kunststoffe zur Reibungs- und Verschleißreduzierung an Wälzlagerkäfigen - Sander, Thomas; Vierneusel, Bernd; Tremmel, Stephan; Wartzack, Sandro (VDI-Berichte 2202, 2013)
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.potent

Potentiale datengestützter Methoden zur Gestaltung und Optimierung mechanischer Fügeverbindungen - Zirngibl, Christoph; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the 31st Symposium Design for X (DFX2020), 2020)
Due to the increasing requirements on lightweight constructions, the demands for efficient joining processes are constantly rising. Therefor cold forming processes provide a faster and less expensive alternative to established thermal joining methods. In order to guarantee the joining reliability, not only the selection of a suitable process, but also the design and dimensioning of the joint is crucial. As a possible solution, data-driven methods offer procedures for the structuring of data and the targeted analysis of product features and key variables. Motivated by this, the paper shows a literature-based approach by using the example of clinching to illustrate the potentials and limits of data-based methods for the design and optimization of mechanical joining processes.<br
Keywords: Clinching; Data-driven optimization; Multiobjective Optimization

Potentiale für den Leichtbau durch Beschichtung von Kunststoffen - Sander, Thomas; Wartzack, Sandro (Design for X. Beiträge zum 21. DfX-Symposium, 2010)
UnivIS-Import:2015-04-16:Pub.2010.tech.FT.FT-KLMEFK.potent

Potentiale von NLP-basierten Assistenzsystemen im Anforderungsmanagement - van Remmen, Judith Sophie; Horber, Dennis; Pickel, Jessica; Götz, Stefan; Wartzack, Sandro (Tagungsband zum Stuttgarter Symposium für Produktentwicklung SSP 2023, 2023)
Die Anwendung und Integration bestehender NLP-basierter Ansätze in das Anforderungsmanagement wird derzeit durch verschiedene Faktoren, darunter mangelndes Expertenwissen und Know-how, gehemmt. Motiviert durch das Fehlen einer Entscheidungshilfe für die Konzeptionierung NLP-basierter Assistenzsysteme fokussiert der vorliegende Beitrag die Entwicklung einer systematischen Handlungsempfehlung zur Potentialidentifikation und Risikominimierung. Die Entscheidungshilfe berücksichtigt dabei die Unternehmensdefinition hinsichtlich der Art des Unternehmens, dessen Produkttypologie und Referenzsysteme. Sie dient dazu, potentiell kritische Anforderungen zu identifizieren und daraus Voraussetzungen für die Umsetzung des NLP-unterstützten Soll-Prozesses abzuleiten. Die qualitative Anforderungs- erfüllung kann dabei als Indikator für das Potential oder Risiko in der Entscheidungsfindung genutzt werden. Diesbezüglich können bereits Herausforderungen für die eigene Implementierung des konzeptionierten Assistenzsystems oder die Beauftragung eines Softwarezulieferers abgeleitet und klar kommuniziert werden. Das entwickelte Konzept wird anhand eines akademischen Beispiels kritisch diskutier
Keywords: Natural Language Processing; Anforderungsmanagement; Digital Engineering

Potentiale von Simulationsdatenmanagementsystemen zur KI-gestützten Vorhersage und Bewertung von Produkteigenschaften - Gerschütz, Benjamin; Sauer, Christopher; Götz, Stefan; Hörmann, Matthias; Wartzack, Sandro (2023)

Potential of arc evaporated TiO2 as an interlayer and its performance in dry sliding - Vierneusel, Bernd; Sander, Thomas; Tremmel, Stephan; Wartzack, Sandro (Proceedings of the 15th Nordic Symposium on Tribology, 2012)
UnivIS-Import:2015-04-16:Pub.2012.tech.FT.FT-KLMEFK.potent

Practice and Experience in High Quality 3D Graph Visualization in Virtual Reality - Müller, Jonas; Harlan, Jakob; Stamminger, Marc; Grosso, Roberto (The application track, posters and demos of EuroVR: Proceedings of the 16th Annual EuroVR Conference - 2019, 2019)
The visualization of complex graphs (abstract networks of nodes, connected by edges) is a long-standing research problem. Virtual reality (VR) offers a very intuitive access to the third dimension in visualization, which can help for the perception of the structure of complex graphs. However, interactive exploration of a graph in VR requires real-time rendering, which is challenging for complex graphs, even on latest high-end GPUs. Furthermore, visual effects that improve perception of the structure of the graph are desirable, but often increase render time even further. In this paper, we describe our experiences with the high-quality rendering of 3D graphs. We show practical solutions for the efficient renderings of such graphs and for the inclusion of visual cues that improve the perception of the graph structure, without hampering real-time exploration capabilities. As a result, we present the three graph rendering techniques that are also shown in the teaser figure. We describe the real-time rendering algorithms behind these techniques, evaluate their perceptual properties, and present performance numbers on a state-of-the-art VR syste
Keywords: graph drawings; virtual reality; application

Prädiktive biomechanische Simulation am Beispiel von ergonomischer Produktoptimierung in Burkina Faso / Predictive biomechanical simulation based on the example of ergonomic product optimization in Burkina Faso - Meißner, Ruth; Wolf, Alexander; Wartzack, Sandro; Miehling, Jörg (Konstruktion, 2022)
In der Produktentwicklung gewinnen nutzerzentrierte Designprozesse zunehmend an Bedeutung. Muskuloskelettale Simulationstools ermöglichen die Abbildung und Simulation des menschlichen Bewegungsapparats während der Nutzer-Produkt-Interaktion auf Basis experimentell erhobener Bewegungsdaten. Durch prädiktive Methoden der Bewegungserzeugung soll der Aufwand der experimentellen Bewegungserfassung reduziert und eine proaktive sowie virtuelle Analyse von Produktergonomie und Gebrauchstauglichkeit ermöglicht werden. Dieser Beitrag präsentiert eine solche prädiktive Methode zur Abbildung der Nutzer-Produkt-Interaktion. Diese wurde für die Designoptimierung eines Trikes für Menschen mit Behinderungen in Burkina Faso entwickelt. In product development, the impact of user-centered design processes is growing rapidly. Biomechanical simulation enables the realistic representation of the human musculoskeletal system during user-product interactions based on experimentally captured motion data. Using predictive methods for motion generation, the effort for experimental motion capture can be reduced enabling a proactive and virtual analysis of product ergonomics and usability. This paper presents such a predictive method for modelling user-product interaction. This was developed for the design optimisation of a tricycle for persons with disabilities in Burkina Fas

Praxisorientierte Lehre: Konzeptentwicklung innovativer Produkte (KIP) - Wartzack, Sandro; Luft, Thomas (WiGeP News, 2014)
Praxisorientierte Lehre: Konzeptentwicklung innovativer Produkte (KIP) Innovative Konzepte zur Verbesserung der Sicherheit von Personen im Straßenverkehr
Keywords: Lehre; Konzeptentwicklung; innovative Produkte

Predicting EHL film thickness parameters by machine learning approaches - Marian, Max; Mursak, Jonas; Bartz, Marcel; Profito, Francisco J.; Rosenkranz, Andreas; Wartzack, Sandro (Friction, 2022)
Non-dimensional similarity groups and analytically solvable proximity equations can be used to estimate integral fluid film parameters of elastohydrodynamically lubricated (EHL) contacts. In this contribution, we demonstrate that machine learning (ML) and artificial intelligence (AI) approaches (support vector machines, Gaussian process regressions, and artificial neural networks) can predict relevant film parameters more efficiently and with higher accuracy and flexibility compared to sophisticated EHL simulations and analytically solvable proximity equations, respectively. For this purpose, we use data from EHL simulations based upon the full-system finite element (FE) solution and a Latin hypercube sampling. We verify that the original input data are required to train ML approaches to achieve coefficients of determination above 0.99. It is revealed that the architecture of artificial neural networks (neurons per layer and number of hidden layers) and activation functions influence the prediction accuracy. The impact of the number of training data is exemplified, and recommendations for a minimum database size are given. We ultimately demonstrate that artificial neural networks can predict the locally-resolved film thickness values over the contact domain 25-times faster than FE-based EHL simulations (R-2 values above 0.999). We assume that this will boost the use of ML approaches to predict EHL parameters and traction losses in multibody system dynamics simulations.
CRIS-Team WoS Importer:2022-06-24

Predicting the Effects of Midsole Materials on Running Using Optimal Control Simulation - Dorschky, Eva; Kurfess, Nicolai; Krüger, Daniel; Schlarb, Heiko; Eskofier, Björn; van den Bogert, Antonie J. (Dynamic Walking 2016, 2016)

Prediction of Lubricant Film Parameters of Deviated EHL Line Contacts using Machine Learning Approaches - Feile, Klara; Bartz, Marcel; Wartzack, Sandro (7th YOUNG TRIBOLOGICAL RESEARCHER SYMPOSIUM, 2024)
Friction losses are, among other factors, significantly caused by manufacturing-related shape deviations of surface topographies, e.g. due to tool vibrations. Until now, the consideration of these shape deviations within the calculation of EHL contacts in the design process of low-friction machine elements with lubricated contacts has only been possible by means of complex and time-consuming numerical simulations. Consequently, the objective of this contribution is to utilize machine learning (ML) approaches in order to significantly accelerate the prediction of lubricant film parameters in 2D line contacts, while accounting for shape deviations in the form of waviness. The numerical simulations used to generate the training and test data sets are discussed first. Subsequently, Gaussian process regression and neural network models are compared, whereby the number of input parameters is reduced due to the use of dimensionless parameters. The results demonstrate the potential of ML models to predict lubricating film parameters quickly and precisely, even when taking shape deviations into accoun

Prediction of Rolling Bearing Cage Dynamics Using Dynamics Simulations and Machine Learning Algorithms - Schwarz, Sebastian; Grillenberger, Hannes; Tremmel, Stephan; Wartzack, Sandro (Tribology Transactions, 2021)
Cage instability or highly dynamic cage movement can have a strong influence on the performance of rolling bearings. In addition to very loud and disturbing noises (“squeal”), bearing failure due to cage fracture can occur. This article deals with two topics: the general classification of cage motions and the prediction of application-dependent cage motions to prevent cage instability during operation. The dependencies of the unstable cage movement on the bearing’s load and geometric characteristics of the cage are analyzed using a large number of sophisticated simulations, based on multibody dynamics. To evaluate the cage movements, first a key figure called the “cage dynamics indicator” (CDI) is introduced, which is used to classify the simulation results by means of quadratic discriminant analysis into three types “unstable,” “stable,” and “circling” (= classification of cage motion). Second, a machine learning algorithm trained and tested on the basis of more than 4,000 simulation results enables a time-efficient prediction of the physical correlations between bearing load and cage properties and the resulting cage dynamics (= prediction of cage motion). A comparison of the calculated cage dynamics with the results of an optical measurement of the cage dynamics rounds off this article. This comparison illustrates the high quality of the simulation models and the training data used for machine learning.
Keywords: Wälzlager; Dynamiksimulation; Käfiginstabilität; Digitale Bildkorrelation; Maschinelles Lernen

Proactive Integration of User Data into Engineering Processes - A Generic Approach and Specific Examples - Wolf, Alexander; Buker, Tina; Molz, Carla; Scherb, David; Wartzack, Sandro; Miehling, Jörg (Human-Automation Interaction. Manufacturing, Services and User Experience, 2022)
User-centered design (UCD) describes an approach, which aims to increase customer satisfaction, comfort, usability, user experience, aesthetics and perceived quality by enhancing the fit between products and their users in the respective context of use. To achieve this goal, a multitude of different methods can be applied. All these methods integrate the user into the design process, in order to evaluate and improve the user-product interaction. This integration can be achieved via two different approaches. The classical approach on the one hand, integrates the user personally, e.g. focus groups, user tests, interviews or surveys. The proactive approach on the other hand, integrates the user in form of a user model, which is universally applicable for one aspect of user-product interaction, e.g. digital human models for the evaluation of physiological comfort and ergonomics or generic high-level guidelines for enhancing positive product emotions. The proactive approach is of great interest for industrial and engineering design, as it offers time- and cost-efficient user integration especially in the early, predominantly virtual phases of product design. This chapter takes a closer look at the proactive approach and presents four specific examples concerning computer aided ergonomics, assistive device design, preoperative evaluation of implants and product-related user stigma.
Keywords: User-centered design; User-product interaction; Proactive user integration

Procedural Concept Design with Computer Graphic Applications for Light-Weight Structures using Blender with Subdivision Surfaces - Denk, Martin; Mayer, Johannes; Wartzack, Sandro (Proceedings of the 33rd Symposium Design for X (DFX2022), 2022)
In today's concept development, it is important to develop customer requirements in advance via prototypes with little effort. Some of these requirements can be pre-tested through virtual product development, although creating them with computer aided design (CAD) software can be time-consuming. In the context of this work, tools commonly used in animation design are adapted to the early phase of virtual product development. This is primarily to limit the time effort of prototyping in product development. However, the models must be led to non-intersecting 3D manifolds to ensure a transfer into computer aided engineering (CAE) or possible manufacturing. Therfore in this work, so-called procedural designs based on computer graphic applications are described and examined for their suitability for CAE.<br

Procedure Model for Structured Relational Modeling of Requirements to Support Requirements-oriented Decision Making - Horber, Dennis; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the Design Society, 2021)
The development of complex technical systems is characterized by a large number of system elements as well as their interactions. With regard to requirements management, many requirements have to be considered, which can have different relations to each other. If these requirements are used as basis for criteria in the decision making process, these relations must also be considered in the multi-criteria evaluation of product alternatives. Therefore, a computer-aided approach is presented in this paper, which allows the systematic modeling of requirement interactions focusing on multi-criteria decision making. For this purpose, basic relation types are identified, which are used to model submatrices in order to derive the Requirement Relation Matrix (RRM). Matrix-based as well as graph-based visualization methods are used for the RRM in order to improve the alternatives with the knowledge about the relational linkage. In addition, the effects of changes in requirements can be transferred to the decision making process. The approach is exemplarily applied to the extension of a test laboratory by a test benc
Keywords: Decision making; Requirements; Dependency; Graph visualization; Product modelling/models

Process and machine selection in sampling-based tolerance-cost optimisation for dimensional tolerancing - Hallmann, Martin; Schleich, Benjamin; Wartzack, Sandro (International Journal of Production Research, 2021)
Tolerance-cost optimisation, i.e. using optimisation techniques for tolerance allocation, is frequently used to determine a cost-efficient tolerance design that can meet the stringent requirements on high-quality products. Besides various manufacturing aspects, the selection of available alternative machines and processes hold great potential for an early optimal process planning by identifying their best combination. Although machine/process selection by minimum cost and mixed-integer optimisation is often applied in theory and practice, their proper implementation in tolerance-cost optimisation based on sampling techniques for tolerance analysis, which can statistically consider various individual part tolerance distributions, has not been studied so far. With the aim to overcome this drawback, this article focuses on machine/process selection in sampling-based tolerance-cost optimisation for dimensional tolerances considering the respective machine characteristics of several machine options, e.g. process capabilities and manufacturing distributions. A comparative study proves that machine/process selection by mixed-integer optimisation leads to minimum total manufacturing costs since it covers the whole search space, including all technically feasible machine combinations and thus identifies the global cost minimum.
CRIS-Team Scopus Importer:2021-07-30
Keywords: alternative machine/process selection; mixed-integer optimisation; optimal tolerance allocation; process planning; statistical tolerance analysis; Tolerance-cost optimisation

Process-Oriented Tolerance and Variation Management: Review and Classification - Litzenburger, Philipp; Götz, Stefan; Margies, Lennard; Bode, Christoph; Müller, Rainer; Wartzack, Sandro (Applied Sciences, 2024)
In the context of tolerance management, the consideration of manufacturing and assembly processes is becoming increasingly important. The main drivers for this are, above all, short development times and high-quality requirements, leading to tight tolerances. To overcome the resulting challenges, many publications address the process-oriented tolerance management. However, since multiple terms and definitions for describing activities that link tolerance management with the production process exist, it is hard to obtain a comprehensive overview on the topic. Therefore, this paper presents a review of existing approaches. The aim is to identify similarities and differences of existing approaches and present them with the help of a classification. For this purpose, among others, work from the areas of process-oriented tolerance management, stream of variation, state space modeling, and variation propagation in multistation manufacturing and assembly systems is considered. Based on the definition of the summarizing term “process-oriented tolerance and variation management”, a classification of this thematic area will be introduced.<br
Keywords: process-oriented tolerancing; stream of variation; state space modeling; process-oriented tolerance and variation management

Process-oriented tolerancing - A discrete geometry framework - Schleich, Benjamin; Wartzack, Sandro (Proceedings of the 19th International Conference on Engineering Design, 2013)
Since the requirements on technical products steadily increase, there exists a growing need for considering all effects which may lead to reduced product quality in engineering design. Geometric variations are a main contributor to malfunction and decreased product quality and have thus to be limited by geometric tolerancing. However, geometric tolerances are a source of disharmonies since manufacturing requires loose tolerances for realizing low manufacturing costs whereas design tends to choose tight tolerances for ensuring the product quality. This paper focuses on an integrated view on process-oriented tolerancing considering information from all stages of the product origination. After highlighting barriers for process-oriented tolerancing, a framework is proposed, which integrates process information in a skin model inspired tolerance analysis approach. This framework takes all sources of geometric deviations into account when evaluating their effects on the product quality. Thereby, manufacturing and assembly aspects can be considered in tolerancing during engineering design, which helps to reduce disharmonies, save manufacturing costs, and increase the product quality.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.proces
Keywords: Computer aided design; Computer aided tolerancing; Design for x; Robust design

Process-Oriented Tolerancing: Consideration of Manufacturing and Operation for Product Assurance Using Virtual Methods - Bode, Christoph; Schächtl, Paul; Schleich, Benjamin; Wartzack, Sandro (Research in Tolerancing, 2024)
A product generally proceeds through development, production and assembly before it goes into operation. In particular, iterations often occur between development and production, although information are usually only passed on systematically in one direction. Errors during development and especially during tolerancing, scheduled at the end of the development phase, are therefore usually not discovered until production, assembly, or operation. The risk of such errors is particularly high in tolerancing for two reasons. First, tolerancing is usually based on expert knowledge or standards, which covers a large proportion of standard cases, but not every case. Second, conventional tolerancing usually focuses on ensuring functionality at the end of production. The manufacturability and the influence of operation in terms of wear are usually not considered. The aim of process-oriented tolerancing is to provide information from production and operation early in the development phase and especially in tolerancing. This enables the tolerance engineer to ensure manufacturability and functionality before and during operation. This chapter provides an overview of process-oriented tolerancing. Both state-of-the-art approaches and a novel holistic approach using virtual methods are presented. The novel approach aims to include all areas involved in tolerancing and to reduce iterations and the time required for testin

Process-Oriented Tolerancing for Additive Manufacturing—Application to Non-assembly Mechanisms - Schächtl, Paul; Schleich, Benjamin; Wartzack, Sandro (Research in Tolerancing, 2024)
Additive manufacturing (AM) is characterized by great design freedom and batch size-independent manufacturing costs, and also offers the possibility of manufacturing moving mechanisms in a single manufacturing step. A subsequent assembly step thus becomes obsolete, consequently leading to a considerable cost reduction. However, AM processes have the disadvantage that lower geometrical accuracy can be achieved compared to conventional manufacturing processes. Part quality is mostly technology- and machine-dependent and there is a lack of reliable and comprehensive information on the relationship between product and process design and achievable tolerances. These characteristics from process design must be considered in the design phase to ensure functionality. Existing approaches for virtual assurance of mechanism operability only deal with conventional manufacturing processes. The central objective of this contribution is to propose a framework for AM process-oriented tolerancing and the specific application for the virtual validation of the motion behavior of non-assembly mechanisms by means of statistical tolerance analysis. Through the deployment of the proposed framework, an analysis of these products prior to manufacturing can be achieved, thus leading to lower failure rates. The results from this analysis are therefore intended to serve as a basis for decision-making within product and process design for AM-inexperienced designer

Produktionsmanagement als effizientes Werkzeug zur Vernetzung von Forschungsprojekten - Ziegler, Christian; Stockinger, Andreas; Stoll, Tobias; Wittmann, Stefan; Weickmann, Johannes; Schmidt, Jürgen; Schuck, Marcus; Cojutti, Massimo; Al-Sheyyab, Ahmad (Zeitschrift für wirtschaftlichen Fabrikbetrieb, 2007)
LFT Import::2019-07-16 (1501)

Produkt- und Prozessdatenmodellierung im Kontext der Blechmassivumformung - Breitsprecher, Thilo; Meinel, Andreas; Thummet, Martin; Wartzack, Sandro (Entwerfen Entwickeln Erleben - EEE2014, 2014)
UnivIS-Import:2015-04-16:Pub.2014.tech.FT.FT-KLMEFK.produk

Produkt- und Prozessparameterdesign additiv gefertigter Mechanismen - Schächtl, Paul; Götz, Stefan; Schleich, Benjamin; Wartzack, Sandro (Konstruktion, 2025)

Properly test planning on the basis of a combined process and product modeling - Wartzack, Sandro; Westphal, Christoph (8th International Conference on Product Lifecycle Management 2011, 2011)
UnivIS-Import:2015-04-16:Pub.2011.tech.FT.FT-KLMEFK.proper

Provision of cross-domain knowledge in mechanical joining using ontologies - Zirngibl, Christoph; Kügler, Patricia; Popp, Julian; Bielak, Christian Roman; Bobbert, Mathias; Drummer, Dietmar; Meschut, Gerson; Wartzack, Sandro; Schleich, Benjamin (Production Engineering, 2022)

Prüfstand für den Tür-Seitencrash - Wartzack, Sandro (Automotive Engineering Partners, 2004)
UnivIS-Import:2015-04-16:Pub.2004.tech.FT.FT-KLMEFK.prfsta

PVD-/PECVD-DLC Thin Coatings as a Potential Solution for Tailored Friction Conditions for Dry Sheet Metal Forming Tools - Zhao, Rong; Tremmel, Stephan (Proceedings 12th International Conference THE "A" Coatings 2016, 2016)
Keywords: DLC Coatings; Dry sheet forming; adesive wear

Quantification of the influence of varying electrode shapes and materials on the thermo-crimping process of standardized tubular cable lugs - Spreng, Simon; Gläßel, Tobias; Muselmann, Johannes; Wörrlein, Marina; Franke, Jörg (2016 6th International Electric Drives Production Conference, EDPC 2016 - Proceedings, 2016)
The main joining task in the field of electric drives production is to connect bundles of insulated copper wires with standardized tubular cable lugs, as this connection alternative is widely used in all types of different electrical stator varieties. Implementing this process in industrial production facilities, the thermo-crimping technology is widely used. Within this technique, the insulation is thermally destroyed, while coincidently, the tubular cable lug and the inlying skinned copper wires are deformed plastically, which generates a force fit crimp-connection. The thermo-crimping process features strong production-related benefits such as short tact times, high process reliabilities as well as an easy process handling. The severe disadvantage however has to be seen within the electrode wearing, as the crimping tools are simultaneously exposed to high pressures and temperatures of at least 600 C reducing an electrode's number of possible crimping routines to at most 1500. As a consequence, especially in serial production, excessive maintenance efforts have to be taken into account, strongly reducing the production efficiency. For this purpose, the institute FAPS focuses its research on the reduction of tool wearing. Beginning with a theoretical process analysis, different tool shapes and materials are compared experimentally considering both, the joint quality and the electrode wearing. Subsequently, regression models are introduced predicting static quality properties such as tensile forces and transition resistances. Finally, the proposed model is validated by applying the found formula to different cable lug sizes.
CRIS-Team Scopus Importer:2023-03-07
Keywords: electric drives manufacturing; thermo crimping; varying electrode shapes

RDTol: Konzeption und Aufbau einer Lehrveranstaltung zum Robust Design und Toleranzmanagement - Schleich, Benjamin; Götz, Stefan; Hallmann, Martin (Erlangen, 2020)

Realization of Modern Educational Concepts in Engineering Design - Meerkamm, Harald; Tremmel, Stephan; Wartzack, Sandro; Stockinger, Andreas (Proceedings of ICED 09, the 17th International Conference on Engineering Design, Vol. 10: Design Education and Lifelong Learning, 2009)
This paper gives an overview of engineering design education at University Erlangen-Nuremberg in order to prompt a discussion about the structure and scope of the proposed educational concept compared to other approaches. Due to the transformation of the traditional German degree programs to an educational system based on two cycles (bachelor/master), a new curriculum had to be performed. The curricula and the according lectures were derived based on a review of demands on product developers. This review and the resulting educational concept are presented in this paper. While setting up the lectures, one of the aims for education in engineering design was to build up and emphasize a close relationship between engineering design, engineering mechanics, materials engineering and production technology. Some of the courses, especially a CAD course and a product development and design project, are explained more in detail. In the first mentioned course, a modern way of computer-supported, "blended learning" was realized. In the second mentioned course, new ground was broken by applying subject-specific knowledge in combination with soft skills by offering an obligatory project already in the bachelor program.
UnivIS-Import:2015-04-16:Pub.2009.tech.FT.FT-KLMEFK.realiz
Keywords: Curriculum redesign; Engineering design education; Methodological and practical training

Reconstruction of Topology Optimized Geometry with Casting Constraints in a Feature-Based Approach - Mayer, Johannes; Denk, Martin; Wartzack, Sandro (Proceedings of the Design Society, 2023)
Topology Optimization (TO) is an established method for the development of high strength and lightweight structural components. However, its results have to be geometrically revised to obtain a computational model that meets product development requirements. Design has to be in accordance with manufacturing constraints. Geometry reconstruction therefore still is a typically manual and tedious task, but increasingly supported by computational and automated approaches. In this paper, the inclusion of a casting constraint in an automated Medial Axis based reconstruction method is presented. Since the Medial Axis provides cross-section values by the computation of maximally inscribed spheres, this information is used for geometry reconstruction and even further for the purposeful adaption of the cross-section to match Heuver's circle method. Thereby, the directed solidification of molten material is considered. With a predefined feeder position, the demonstrator of a suspension control arm is used to show the application of the method. Resulting CAD-models are also structurally evaluated for their stiffness characteristic
Keywords: Topology Optimization; Medial Axis Transform; Computational Design Methods; Computer Aided Design (CAD); Lightweight Design

Reibungsarme PVD-/PACVD-Festschmierstoffschichten für trockenlaufende, wälzgelagerte Linearführungen - Steinmann, Marc; Tremmel, Stephan; Seitz, Alexander; Meerkamm, Harald (VDI-Fachtagung Gleit- und Wälzlagerungen 2006: Gestaltung, Berechnung, Einsatz (VDI-Berichte 1942), 2006)
UnivIS-Import:2015-04-16:Pub.2006.tech.FT.FT-KLMEFK.reibun

Reibungsreduzierung in EHD-Kontakten durch mikrostrukturierte Bauteiloberflächen - Auslegung, Gestaltung und umformtechnische Herstellung - Tremmel, Stephan; Marian, Max; Zahner, Michael; Weschta, Martin; Engel, Ulf; Wartzack, Sandro; Merklein, Marion (58. Tribologie-Fachtagung. 2017, Son-derband Abschlusskolloquium „Ressourceneffiziente Konstruktionselemente“ SPP 1551 der DFG, 2017)
Gezielt eingebrachte, definierte Oberflächenmikrostrukturen bieten in elastohydrodynamischen (EHD) Kontakten Potential zur Reibungsreduzierung und können damit die Energieeffizienz technischer Systeme erhöhen. Um die größtmögliche Wirksamkeit zu erreichen, sind diese Oberflächenmikrostrukturen auf die jeweilige Anwendung abzustimmen. Die Realisierung theoretisch genauer Mikrostrukturen ist zudem durch die Fertigungstechnik limitiert. Des Weiteren bestimmt das Verschleißverhalten der Mikrostrukturen im Einsatz die Bauteillebensdauer. Für einen wirksamen Einsatz über den gesamten Produktlebenszyklus hinweg bedarf es somit eines grundlegenden Verständnisses der Zusammenhänge zwischen Gestaltung, Herstellung und Einsatzverhalten oberflächenstrukturierter Bauteile. Vor diesem Hintergrund werden im vorliegenden Beitrag ein Simulationsansatz zur Untersuchung der Wirkweise von Oberflächenmikrostrukturen vorgestellt sowie eine Methodik abgeleitet, die die systematische Auslegung und Gestaltung von Oberflächenstrukturen erlaubt. Die Methodik erlaubt die Berücksichtigung individueller tribologischer Belastungskollektive und fertigungstechnischer Restriktionen. Die Fertigungsrestriktionen bei der Strukturerzeugung wurden im Hinblick auf industrielle Maßstäbe für einen Mikroprägeprozess ermittelt. Auf Basis tribologischer Untersuchungen auf einem Nocken/Stößel-Komponentenprüfstand erfolgt die Beurteilung des Reibungs- und Verschleißverhaltens der mikrostrukturierten Bauteil
LFT Import::2019-08-05 (2259)
Keywords: Elastohydrodynamik; Mikrostrukturen; Mikroprägen

Reinforcement Learning As an Alternative for Parameter Prediction In Design for Sheet Bulk Metal Forming - Dworschak, Fabian; Sauer, Christopher; Schleich, Benjamin; Wartzack, Sandro (Volume 2: 42nd Computers and Information in Engineering Conference (CIE), 2022)
This contribution presents an approach and a case study to compare Reinforcement Learning (RL) and Genetic Algorithms (GA) for parameter prediction in Sheet Bulk Metal Forming (SBMF). Machine Learning (ML) and Multi-Objective Optimization (MOO) to provide different points of view for the prediction of manufacturing parameters. While supervised learning depends on sufficient training data, GA lack the ability to explain how sufficient parameters were achieved. RL could help to overcome both issues, as it is independent from training data and can be used to learn a policy leading towards suitable parameter combinations, which can be tracked through the solution space. To probe RL in terms of feasibility for parameter prediction and necessary training effort SBMF serves as an appropriate use case because solution and objective function space are multidimensional, and their relations are challenging for MOO. The results of a Reinforcement Learner and a GA are compared and discussed to answer the question under which circumstances RL can provide an alternative for parameter prediction.<br

Reinforcement Learning for Engineering Design Automation - Dworschak, Fabian; Dietze, Sebastian; Wittmann, Maximilian; Schleich, Benjamin; Wartzack, Sandro (Advanced Engineering Informatics, 2022)
Reinforcement Learning has proven to be capable of solving complex tasks like playing video games, robotics control, speech or image recognition and processing. Transferring Reinforcement Learning into engineering design helps to overcome two current issues of data-driven Design Automation in engineering design. First, dealing with sparse training data resulting from differing design samples. Second, overcoming the limited number of samples in the training data as consequence of short or insufficient product history. To introduce an alternative approach for Design Automation, this contribution studies feasiblity, training effort and transferability of Reinforcement Learning in engineering design. The presented method maps engineering requirements and parametric models into learning environments and provides a novel approach for design automation. In addition to that, the contribution summarises the hyperparameters, which design engineers have to set prior to training, and introduces a novel transfer learning concept for Reinforcement Learning in related design tasks. The support is probed by design tasks of performance-oriented bike parts. Case-independent indicators are presented to estimate the case-specific training effort, the effects of hyperparameter variation and the effects of transferring a pretrained agent to related design tasks. Finally, the findings are used to compare Reinforcement Learning to other data-independent Design Automation approaches to assess potential fields of application for Reinforcement Learning in engineering desig
Keywords: Reinforcement Learning; Design Automation; Deep Q-learning

Requirement analysis for contextual management and supply of process- and design knowledge - a case study - Luft, Thomas; Wartzack, Sandro (DS 70: Proceedings of DESIGN 2012, the 12th International Design Conference, 2012)
This paper provides a methodology for analysing requirements for a knowledge management system that consists basically of a management and search functionality. On basis of a theoretical developed methodology, a requirement analysis for a knowledge management system in an industrial case study is presented. Therefore an analysis of the knowledge and information basis as well as of the needs and mentalities of employees is conducted. As a result all requirements for the management functionality and the search functionaly of a holistic knowledge management system are identified and described.
UnivIS-Import:2015-04-16:Pub.2012.tech.FT.FT-KLMEFK.requir
Keywords: Case study; Knowledge management; Product development process; Requirement analysis

Research in Tolerancing - Wartzack, Sandro (Research in Tolerancing, 2024)
Product development and manufacturing face a variety of challenges resulting from today’s dynamic markets, such as increasing complexity, rising quality demands, and required efficiency. Translating these challenges to tolerancing, there is a considerable need for new and innovative approaches to assist design engineers with the various tasks involved in this area. This textbook therefore focuses on current research topics in tolerancing and is aimed at researchers who are already working in this field or who plan to contribute new approaches to this interesting topic. This first chapter of Research in Tolerancing serves introductory purposes, first with a short introduction to the topic and the motivation for the book, second with insights into the exchange of tolerancing research between academia and industry, and third with an outline of the book’s structure and contents. The latter summarizes the four main parts of Research in Tolerancing: Part 1–Interconnected Tolerancing Activities and Robust Design, Part 2–Advanced Tolerance Analysis and Synthesis Methods, Part 3–Tolerance Analysis Methods for Non-geometrical Key Characteristics, and Part 4–Process- and Operation-oriented Tolerance Managemen
Keywords: Tolerance management; Robust Design; Skin Model Shapes; Systems in motion; Tolerance-cost optimization; Rolling bearing; Validation of functional limiting positions; Process-oriented tolerance management; Additive manufacturing; Composite structures; Tolerance management 4.0

ResNet networks for plausibility detection in Finite Element simulations - Bickel, Sebastian; Schleich, Benjamin; Wartzack, Sandro (Proceedings of NordDesign 2022: How Product and Manufacturing Design Enable Sustainable Companies and Societies, 2022)
Nowadays, the efficient execution of product design and process planning activities without the extensive use of Finite Element (FE) simulation is hardly conceivable. The ability to virtually test components at an early stage can reduce costs while significantly increas-ing product quality. In addition, the current business environment promotes ever shorter development times coupled with a greater variety of products. This combination poses the risk that more and more inexperienced users from the field of product design have to perform simulation and validation tasks. An idea to support the less experienced users is to automatically check their FE models and simulations for plausibility. This helps to con-duct simulations independently by alerting the designers when major errors occur. One approach to the automatic plausibility check of FE simulations utilizes simulations that have already been calculated as a database and applies them to train a Deep Learning model that classifies the new simulations into plausible and non-plausible. This requires converting the existing data into a uniform format by the projection method, so it is read-able for a Deep Learning network. However, for this method to be applied in an industrial environment, a high recognition accuracy is required for unknown simulations. Therefore, the goal of this paper is to investigate the ability of a new Deep Learning architecture to check the plausibility of FE simulations. The objective is to achieve the highest possible recognition accuracy. So far, mainly serial network types have been used for this procedure, which will now be extended by the application of ResNet networks. These have different paths in their structure through the addition of skip-connections, allowing for a theoretically better-trained model. This will be analysed together with a new dataset of simulations. These components for the structural mechanical simulation are geometrically varied and served to evaluate the new network types and their achieved accuracy.
CRIS-Team Scopus Importer:2022-12-09
Keywords: data driven design; data mining; Deep Learning; Plausibility checks; structural analysis

Result Visualization and Documentation of Tolerance Simulations of Mechanisms - Walter, Michael; Pribek, Michael; Sprügel, Tobias; 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)
Imprecise manufacturing processes lead to products which differ in their dimensions and shape. As a consequence, the product developer has to specify appropriate tolerances to limit these deviations and thus to ensure the adequate functional and aesthetic quality of the final products. These tolerances, however, affect several departments of a company, such as manufacturing, technical procurement, metrology or quality control. Hence, insights gained during tolerance analysis and tolerance synthesis must be documented and visualized in a clear and comprehensive manner toward all departments involved. This paper presents an academic recommendation on a comprehensive visualization and documentation of the results of statistical tolerance simulations, focusing on systems in motion which underlie different kinds of deviations. These so-called mechanisms demand a more detailed result visualization than common static (non-moving) systems. The implemented academic tool called “Tol/Mech–insight” provides a comprehensive result visualization and documentation for tolerance simulations of mechanisms and may serve as a sufficient basis for decision-making among experts in various departments.
UnivIS-Import:2015-10-26:Pub.2015.tech.FT.FT-KLMEFK.result
Keywords: Robust design; Tolerance representation and management; result visualization

Retrieving knowledge and information by using a systematic search interface - An industrial case study - Luft, Thomas; Wartzack, Sandro (NordDesign 2012 - Proceedings of the 9th NordDesign Conference, 2012)
Knowledge and information are nowadays the most important factors for the development of modern and innovative products. Therefore the efficient management and contextual supply of knowledge is nowadays becoming increasingly essential because more knowledge and information needs to be considered by engineers. However, there are a variety of problems in handling and retrieving knowledge and information in particular in the engineering design process. Existing IT systems do not meet the requirements of the users or do it only in an insufficient way. In this paper which is based on an industrial case study the identification and in particular the classification of “Knowledge and Information-Objects” of the considered company is described. These two steps are one of the most important preconditions for a holistic and computer-based knowledge management system from a management and a supply oriented view. In order to customise a systematic search interface that meets the requirements of the employees, an appropriate number of workshops with experts from different departments have to be organised. The focus of this paper is on a (combined) content- and source-based systematic search interface for knowledge and information retrieval.
CRIS-Team Scopus Importer:2020-04-28
Keywords: Industrial case study; Information retrieval; Information storage; Knowledge management; Product development; Requirement analysis

Retrieving knowledge and information by using a systematic search interface – an industrial case study - Luft, Thomas; Wartzack, Sandro (DS 71: Proceedings of NordDesign 2012, the 9th NordDesign conference, 2012)
Knowledge and information are nowadays the most important factors for the development of modern and innovative products. Therefore the efficient management and contextual supply of knowledge is nowadays becoming increasingly essential because more knowledge and information needs to be considered by engineers. However, there are a variety of problems in handling and retrieving knowledge and information in particular in the engineering design process. Existing IT systems do not meet the requirements of the users or do it only in an insufficient way. In this paper which is based on an industrial case study the identification and in particular the classification of “Knowledge and Information-Objects” of the considered company is described. These two steps are one of the most important preconditions for a holistic and computer-based knowledge management system from a management and a supply oriented view. In order to customise a systematic search interface that meets the requirements of the employees, an appropriate number of workshops with experts from different departments have to be organised. The focus of this paper is on a (combined) content- and source-based systematic search interface for knowledge and information retrieval.
Keywords: knowledge management; product development; requirement analysis; information storage; information retrieval; industrial case study

Retrofitting Digital Twins of Existing Systems - Fett, Michel; Macko, Stanislav; Wilking, Fabian; Götz, Stefan; Wartzack, Sandro; Kirchner, Eckhard (2024 IEEE International Symposium on Systems Engineering (ISSE), 2024)
Digital Twins offer a wide range of potentials in an industrial context but are rarely used in practice. Small and medium-sized companies in particular face challenges that can only be overcome with great effort and risk. One of these challenges is the fact that the development of Digital Twins is a complex and interdisciplinary task, for which small and medium-sized companies can rarely provide the necessary resources. Another challenge is that tight budgets lead to equipment and systems being used for a longer time and often do not provide the necessary elements for the use of Digital Twins. Therefore, this article presents an approach for retrofitting existing systems for Digital Twins by considering its three domains: models, sensors and IT infrastructure. The results are illustrated using a case stud

Reverse Engineering - Prozess, Technologien und Anwendungsfälle - Katona, Sebastian; Koch, Michael; Wartzack, Sandro (16. Bayreuther 3D-Konstrukteurstag, 2014)
Keywords: Reverse Engineering

Review of the mechanisms of action in the musculoskeletal system as a basis for new simulation models - Uttich, Eike; Bartz, Marcel; Bender, Beate (8th World Congress of Biomechanics, 2018)

Rheological behavior of an artificial synovial fluid – influence of temperature, shear rate and pressure - Rothammer, Benedict; Marian, Max; Rummel, Florian; Schroeder, Stefan; Uhler, Maximilian; Kretzer, J. Philippe; Tremmel, Stephan; Wartzack, Sandro (Journal of the Mechanical Behavior of Biomedical Materials, 2021)
Despite the excellent clinical performance of joint replacements, wear-induced aseptic loosening is a main cause of premature implant failure. Tribological testing is usually carried out using bovine serum as an artificial synovial fluid. In order to gain new insights into the suitability to simulate human synovial fluid and provide recommendations for the conditions of tribological testing, accurate rheological measurements on the influence of temperature, shear rate and pressure on density and viscosity were performed. Thus, a temperature dependence of density and viscosity could be verified, whereas both values decreased with higher temperatures. The temperature dependency of viscosity could be approximated by an Arrhenius model. Moreover, shear-thinning characteristics could be demonstrated and fitted to a Cross model, which agreed well with investigations on human synovial fluid reported in literature. Furthermore, an anomaly of pressure dependence of viscosity was found and correlated with the behavior of water as a main constituent. At room temperature, the viscosity initially decreased to a minimum and then increased again as a function of pressure. This was no longer distinct at human body temperatures. Consequently, the present study confirms the suitability of bovine serum as a substitute synovial fluid and emphasizes the importance of realistic testing conditions in order to ensure transferability and comparability.<br
Keywords: Bovine serum; Biomedical rheology; Temperature dependence; Shear-thinning; Pressure dependence

Roadmap für die Entwicklung einer Methodik zur dualen Nutzerintegration - Schröppel, Tina; Miehling, Jörg; Wartzack, Sandro (Stuttgarter Symposium fur Produktentwicklung, 2019)
Um den Herausforderungen wachsender und umkämpfter Märkte begegnen zu können, müssen Produkte heutzutage mehr denn je die Bedürfnisse der Nutzer erfüllen. Neben einer ergonomischen Produktgestaltung treten dabei zunehmend subjektive Faktoren in den Vordergrund. Ein gut für den Nutzer ausgelegtes Produkt berücksichtigt somit physiologische wie subjektive Bedürfnisse gleichermaßen. Bisherige nutzerzentrierte Ansätze fokussieren sich jedoch häufig auf nur einige wenige Nutzeraspekte. Es fehlt demnach an einer systematischen Vorgehensweise, mit der eine objektive Absicherung einer subjektiv-nutzergerechten und zugleich körperlich-geeigneten Produktgestaltung sichergestellt werden kann. Die duale Nutzerintegration stellt eine solche Methodik dar. Basierend auf einer kontextneutralen Nutzer- und Produktbeschreibung sowie einer physiologischen und subjektiven Produktbewertung wird eine zielgruppenorientierte Produktgestaltempfehlung gegeben. Der vorliegende Beitrag stellt die Roadmap für die Entwicklung der Methodik dualer Nutzerintegration inklusive dem hierfür benötigten Forschungsbedarf vor.<br
CRIS-Team Scopus Importer:2024-12-16
Keywords: Nutzerintegration; subjektive Produktgestaltung; physiologische Produktgestaltung

Roadmap to Consider Physiological and Psychological Aspects of User-product Interactions in Virtual Product Engineering - Wartzack, Sandro; Schröppel, Tina; Wolf, Alexander; Miehling, Jörg (Proceedings of the 22nd International Conference on Engineering Design (ICED19), 2019)
To successfully facilitate user-centred design, a multitude of different aspects has to be considered, from purely physiological to psychological-emotional factors. The overall aim is to increase the customer satisfaction by enhancing the fit between products and their users in the respective context of use. Further virtualisation of user-centred design processes holds the potential to convey the concepts of frontloading and predictive engineering from classical product engineering. Our vision is to facilitate a comprehensive consideration of user-product interactions in virtual product engineering operationalised by the mission to develop methods and tools to assess and design user-product interactions according to physiological and psychological aspects. A variety of work has already been done to model musculoskeletal user groups, to configure, predict, simulate and optimise physical user-product interactions, to integrate such models into CAD or to map individual subjective values to product design. Nevertheless, there are still research areas to be addressed to enable a comprehensive implementation of the mentioned approach. These are discussed in the present contribution
Keywords: User centred design; Simulation; Integrated product development; Affective Engineering; Biomechanical digital human models

Roboterassistenz in der Behindertenwerkstatt: Intuitiv bedienbare, sichere und flexible Zusammenarbeit mit Industrierobotern - Leutert, F.; Ramer, Christina; Pirkl, G.; Bahle, G.; Poxrucker, A.; Dresselhaus, M.; Ziegler, Christoph; Schilling, K.; Franke, Jörg; Lukowicz, P. (wt Werkstattstechnik - Online, 2014)
For a successful collaboration between humans and robotic assistants in a shared workspace, users must be enabled to intuitively understand robotic data and work processes, to easily operate the robot while being protected from harm by safety systems. This article introduces an assistance system employed in sheltered workshops that achieves these goals using Augmented Reality, novel input devices, and automatic collision avoidance.
Keywords: B|Mech

Robust Conceptual Design for a Robust Early Embodiment Design - Horber, Dennis; Li, Jiahang; Grauberger, Patric; Götz, Stefan; Matthiesen, Sven; Wartzack, Sandro (Proceedings of NordDesign 2024, 2024)
Utilisation of Robust Design (RD) principles in early stages of product development can reduce costly iterations by identifying concepts that are less prone to functional losses caused by variations. Valuable implications can be drawn from those principles, which are currently not transferred to later stages. Motivated by that, the RD principles are studied with the EFRT-Model. The transferability of nine different RD principles to later stages is analysed with a variation simulation of the exemplary snap fit joint use case and discussed based on their utilisation on a four-point scal
Keywords: Robust Design; Simulation Based Design; Embodiment Design

Robust-Design-Optimization of mechanisms based on kinematic requirements considering uncertainties - Heling, Björn; Schleich, Benjamin; Wartzack, Sandro (15th CIRP CAT 2018 - CIRP Conference on Computer Aided Tolerancing, 2018)
Today the market environments require products to be developed by multidisciplinary teams, which have to consider contradictory requirements in drastically reduced times-to-market. In this context, the importance of robust design ambitions, which strive for developing products that are insensitive to variations from manufacturing, assembly and use processes, increases. In this paper, a novel methodology for the robust-design optimization of a mechanism is introduced, which allows optimizing the mechanism so that contradictory requirements are met despite the presence of geometrical deviations and uncertainties during use. The result of this optimization process are mechanisms, which do not only fulfill kinematic requirements, but are also insensitive to geometrical part deviations and uncertain ambient parameter
Keywords: Tolerance-CostOptimization; Skin Model Shapes; Process-oriented Tolerancing

Robust design proposal by the use of structural topology optimization considering uncertainties of input parameters and boundary conditions - Stangl, Thomas; Walter, Michael; Wartzack, Sandro; Schneyer, Thomas (Proceedings of the 19th International Conference on Engineering Design, 2013)
Specifying a product's optimal mechanical and functional design primary depends on the requirements defined by the future operating conditions. In today's product design process the usage of topology optimization is a widely applied computer aided method to define an optimal design considering these requirements. However, in an early design stage, input parameters for this structural optimization process (e.g., operation conditions) are usually uncertain. Consequently, the resulting design is not optimal. This paper focuses on a detailed investigation of uncertainties in structural topology optimization. Hence, the different kinds of uncertainties and their effects on the resulting designs are considered in detail. Furthermore, a methodology is presented, which enables the consideration of uncertainties using e.g., a statistical investigation of the topology optimization results and a sensitivity analysis-based result visualization. Therefore, a cam drive rocker arm of a combustion engine is analyzed in a case study. Finally, several recommendations are derived, supporting the product developer to define a robust initial design, causing less computational and time expense.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.robust
Keywords: Design engineering; Early functional validation; Optimisation; Robust design; Uncertainty in topology optimization

Robust estimation of clinch joint characteristics based on data-driven methods - Zirngibl, Christoph; Schleich, Benjamin; Wartzack, Sandro (International Journal of Advanced Manufacturing Technology, 2022)
Given a steadily increasing demand on multi-material lightweight designs, fast and cost-efficient production technologies, such as the mechanical joining process clinching, are becoming more and more relevant for series production. Since the application of such joining techniques often base on the ability to reach similar or even better joint loading capacities compared to established joining processes (e.g., spot welding), few contributions investigated the systematic improvement of clinch joint characteristics. In this regard, the use of data-driven methods in combination with optimization algorithms showed already high potentials for the analysis of individual joints and the definition of optimal tool configurations. However, the often missing consideration of uncertainties, such as varying material properties, and the related calculation of their impact on clinch joint properties can lead to poor estimation results and thus to a decreased reliability of the entire joint connection. This can cause major challenges, especially for the design and dimensioning of safety-relevant components, such as in car bodies. Motivated by this, the presented contribution introduces a novel method for the robust estimation of clinch joint characteristics including uncertainties of varying and versatile process chains in mechanical joining. Therefore, the utilization of Gaussian process regression models is demonstrated and evaluated regarding the ability to achieve sufficient prediction qualities.
CRIS-Team Scopus Importer:2022-12-02
Keywords: Clinching; FEM; Machine learning; Mechanical joining; Robust product design

Robuste, verkürzte Prozesskette durch DfX-Workbenches: Praxisbeispiel Gussgerechtheit - Koch, Alexander; Wittmann, Stefan (Beiträge zum 26. DfX-Symposium, 2015)

Robustheitsbewertung von Produktkonzepten auf Basis von Graphen - Kirchner, Philipp; Götz, Stefan (Summer School Toleranzmanagement - Beiträge zur 4. Summer School - September 2020, 2020)

Robustness Analysis of Pin Joining - Römisch, David; Zirngibl, Christoph; Schleich, Benjamin; Wartzack, Sandro; Merklein, Marion (Journal of Manufacturing and Materials Processing, 2022)
The trend towards lightweight design, driven by increasingly stringent emission targets, poses challenges to conventional joining processes due to the different mechanical properties of the joining partners used to manufacture multi-material systems. For this reason, new versatile joining processes are in demand for joining dissimilar materials. In this regard, pin joining with cold extruded pin structures is a relatively new, two-stage joining process for joining materials such as high-strength steel and aluminium as well as steel and fibre-reinforced plastic to multi-material systems, without the need for auxiliary elements. Due to the novelty of the process, there are currently only a few studies on the robustness of this joining process available. Thus, limited statements on the stability of the joining process considering uncertain process conditions, such as varying material properties or friction values, can be provided. Motivated by this, the presented work investigates the influence of different uncertain process parameters on the pin extrusion as well as on the joining process itself, carrying out a systematic robustness analysis. Therefore, the methodical approach covers the complete process chain of pin joining, including the load-bearing capacity of the joint by means of numerical simulation and data-driven methods. Thereby, a deeper understanding of the pin joining process is generated and the versatility of the novel joining process is increased. Additionally, the provision of manufacturing recommendations for the forming of pin joints leads to a significant decrease in the failure probability caused by ploughing or buckling effects.
CRIS-Team Scopus Importer:2022-11-04
Keywords: joining by forming; pin joining; robustness analysis; versatile joining process

Robustness evaluation in early phases of product development - Li, Jiahang; Horber, Dennis; Grauberger, Patric; Götz, Stefan; Wartzack, Sandro; Matthiesen, Sven (2023)

Robustness Evaluation of Product Concepts based on Function Structures - Götz, Stefan; Hartung, Jonas; Schleich, Benjamin; Wartzack, Sandro (Proceedings of the 22nd International Conference on Engineering Design (ICED19), 2019)
Due to the varying environment conditions as well as the manufacturing induced deviations, the properties of products vary. In order to still meet the increasingly tightening of functional requirements, tolerancing as well as Robust Design practices became integral parts of the product development. However, despite the fact that the robustness of a product is mainly determined by its conceptual design in early design stages, these activities are usually carried out at the end of the design process. In order to overcome this shortcoming, this contribution shows a method that supports the selection of robust principal solutions and thus contributes to the design of product concepts, which are less sensitive to variations. The novelty lies in the adaption and combination of robust design criteria for the quantitative robustness evaluation in the conceptual design stage. First the product characteristics, which are relevant for the product robustness are determined on the basis of the function structure. By using an adopted VMEA and a newly developed evaluation matrix, this allows a thorough robustness evaluation of product concepts. The method is exemplary shown for a lifting table.<br
Keywords: Robust design; Conceptual design; Tolerance representation and management; QFD; VMEA

Robust optimization of continuously reinforced composites in the motorcycle industry - Kellermeyer, Markus; Perterer, Martin; Wartzack, Sandro (RDO-Journal, 2017)

Robust Tolerance Design of Systems with varying ambient Temperature influence due to worldwide manufacturing and operation - Sprügel, Tobias; Walter, Michael; Wartzack, Sandro (International Design Conference - DESIGN, 2014)
In today’s industrial environment products must be developed and brought to market in short time. To shorten the time-to-market between the product idea and the start-of-production various methods were developed over the last decades, which are applied during product development (e. g. concurrent engineering). However, the product developer still has to face additional challenges in modern product development [Liu 2009]. In this context, an extended relevance and discussion on quality topics and in particular, Robust Design Methods (RDM), both in industry and research, can be found in recent years [Gremyr 2003, Liu 2009, Eifler 2013]. These RDMs (which can be principles, tools, methods, metrics etc.) are used to analyze a product in order to reduce the sensitivity of its design parameters towards variation [Eifler 2013]. However, deviations of parts are inherently inevitable due to “axiom of manufacturing imprecision” [Zhang 2011]. Consequently, the product developer has to define appropriate tolerances to limit these dimensional and geometrical deviations and thus, to ensure a certain quality of the entire product [Wartzack 2011]. Therefore, statistical tolerance analyses are widely used in engineering design to quantify the effects of appearing deviations on functional key characteristics (FKCs) of a product [Jayaprakash 2012, Tsai 2012, Chase 1991, Walter 2013]. Tolerance analyses lead to significant cost reductions, as only required tolerance ranges may be manufactured [Söderberg 2006]. Unnecessarily narrow tolerance ranges, which lead to high production costs can be avoided or significantly reduced. However, the analysis of only dimensional and geometrical tolerances is not sufficient to evaluate functionality and assemblability of a system and thus, to achieve a robust design. Other aspects, such as deformation, thermal expansion, wear, etc. need to be integrated in tolerance analysis [Scholz 1995, Chase 1991]. However, existing approaches only consider the impact of these additional effects. So the authors claim that a holistic robust tolerance design essentially requires the consideration of both the impact as well as the cause of these deviations. These causes can be both technical (such as forces, friction) and non-technical (the company’s choice on the place of production, quality philosophy, qualification of workers, etc.). This is even the more serious, since traditionally product developers hardly take into account non-technical causes during product development and tolerance analyses, particularly.
UnivIS-Import:2015-04-16:Pub.2014.tech.FT.FT-KLMEFK.robust
Keywords: robust design; tolerance analysis; worldwide manufacturing; climate effects

Rolling Bearing Calculation with Deviated Components: Incorporating Geometrical Imperfections in the Layout Process of Rolling Bearing Assemblies - Kramer, Vincent; Wartzack, Sandro (Research in Tolerancing, 2024)
Rolling bearings range among the most important machine elements and are frequently deployed wherever rotating parts must be supported. Consequently, they are typically subject to a high number of load cycles, which may cause fatigue resulting in premature failure. The layout of bearings and their seats is therefore a crucial activity during the design of many mechanical systems such as transmissions. Bearing sizes must be chosen such that functional requirements (e.g., with regard to service life) are met while costs and weight are kept at bay at the same time. Within the state of the art, bearing calculations are regularly carried out based on the nominal shapes of the bearings and seat surfaces. However, real parts inevitably exhibit statistically distributed geometrical errors, which may cause changes of the load distribution within the bearings and thus affect vital quantities like fatigue life or operating clearance. This contribution presents a sampling-based method for the incorporation of deviated part geometries in the layout process of rolling bearing assemblies, enabling a more realistic calculation. The method is then demonstrated on an exemplary use case. Finally, remaining challenges are discussed and potential fields for future research are derive

RSM-DT: Reusable System Models for Digital Twins by Utilizing and Automating SysML Profiles - Wilking, Fabian; Fett, Michel; Götz, Stefan; Kirchner, Eckhard; Wartzack, Sandro (2024 IEEE International Symposium on Systems Engineering (ISSE), 2024)
Driven by the opportunities for condition monitoring and other new business models, Digital Twins have become a popular topic within research and industrial application over the last years. This contribution presents an approach for the reuse and utilization of system models as core models for the Digital Twin. Furthermore, it aims to build up the digital architecture as well as present a method to reuse the models over the product lifecycle. For this, a SysML profile is introduced to integrate the elements of the Digital Twin into the development phase. In addition, an approach is presented to automate these models and contribute towards reusable system models for Digital Twins (RSM-DT
Keywords: Digital Twin; MBSE; SysML; System Model; Systems Engineering

Sampling-based tolerance analysis: the key to establish tolerance-cost optimization in the product development process - Hallmann, Martin; Schleich, Benjamin; Wartzack, Sandro (Procedia CIRP, 2021)
Tolerance allocation during detail design aims to identify a combination of tolerances which are tight enough to ensure total product functionality but also as wide as possible to minimize the resultant manufacturing costs. Optimization techniques automatize and thus significantly accelerate the complex search for suitable tolerance values taking both the design and manufacturing perspective into account. While sampling techniques became well-established for tolerance analysis, statistical approximative approaches, e.g. the root sum square method, are still commonly used for tolerance-cost optimization. However, this leads to a limited applicability and validity of the optimization which currently prevents its successful implementation in industry. Thus, the article discusses the direct and indirect effects of sampling methods on the definition and solution of the optimization problem and reveals the benefits and drawbacks of sampling-based tolerance-cost optimization in terms of effectiveness and efficiency using an illustrative case study. In addition, guidelines as well as recommendations for its proper application in research and industry are given. In doing so, this article shows that the use of sampling-based techniques can significantly contribute to a shift of tolerance-cost optimization from an expert tool for tolerance specialists with in-depth knowledge in statistics, optimization and programming, to a user-friendly engineering design tool with an enhanced usability, which enables solving problems of industrial complexity.<br
Keywords: Tolerance-cost optimization; Sampling techniques; Statistical tolerance analysis; Least cost tolerance allocation

Sampling-Based Tolerance-Cost Optimization: Automating Least-Cost Tolerance Allocation Through Joint Metaheuristic Optimization and Sampling-Based Tolerance Analysis - Roth, Martin; Wartzack, Sandro (Research in Tolerancing, 2024)
Tolerance allocation is an essential tolerancing activity to assure the manufacturability of the individual parts, their assembly to the final product, and its functionality in use. Design engineers are responsible for assigning the values for all tolerances specified to limit the critical geometrical part variations. The challenge is to allocate them only as tight as necessary but as wide as possible to simultaneously assure high assembly quality and an economic manufacturing process. Over the last decades, tolerance-cost optimization has turned from first ideas into an effective instrument to address both quality and cost aspects by reformulating and automatically solving the tolerance allocation problem as a mathematical optimization problem. This article presents the basics of sampling-based tolerance-cost optimization. It gives detailed insights in the single methods and their interaction and emphasizes the benefits and challenges when incorporating sampling techniques for tolerance analysis in the optimization workflow. It further introduces a solution for considering multiple, interrelated assembly response functions and geometrical part tolerances correlating on feature, part, and assembly level. An exemplary application illustrates the presented aspects and serves as the basis to discuss the current research gaps and future challenges in this research fiel

Sampling-based Tolerance-Cost Optimization of Systems with Interrelated Key Characteristics - Hallmann, Martin; Schleich, Benjamin; Wartzack, Sandro (Procedia CIRP, 2020)
Robustness is a key factor contributing to a high functionality of technical systems under uncertainty. In this context, existing methodologies, such as Axiomatic Design and Quality Function Deployment, can help to identify coupled functional requirements which significantly affect the robustness of a system. However, it is often not possible to decouple all in the final product design. As a consequence, multiple interrelated tolerance chains have to be considered in the subsequent tolerance design leading to multi-constrained or multi-objective optimization problems. Despite their significant influence on the optimization process and its results, interrelated tolerance chains have not been studied in detail yet, especially in the context of sampling-based tolerance-cost optimization. Moreover, a holistic framework for the tolerance-cost optimization of systems with multiple key characteristics is missing so far. In order to close that gap, this paper presents a framework to consider multiple key characteristics in both least-cost and best-quality tolerance-cost optimization using sampling techniques for tolerance analysis. Therefore, interrelated tolerance chains and their effects on the optimization process in terms of the definition and handling of multiple constraints and objectives are discussed in detail. The proposed research aims to bring all important aspects together in one common framework. Thus, it is supposed to help researchers and practitioners to properly define and solve the tolerance optimization problem. In order to show its benefits and applicability, it is applied to an illustrative case study. The novelty of this paper is to present a comprehensive method to support the tolerance engineer in creating a robust and optimal tolerance design of products with multiple interrelated key characteristics.<br
Keywords: Tolerance-cost optimization; Optimal tolerance allocation; Interrelated key characteristics; Multi-objective optimization

Sampling-based Tolerance-Cost Optimization: The Key to Optimal Tolerance Allocation - Roth, Martin (FAU University Press, 2024)
Limiting manufacturing-caused part variations by size, location, orientation, and form tolerances primarily aims to assure the total assembly quality. At the same time, however, the manufacturing conditions and, thus, the manufacturing costs are already predefined in the product development phase. The method of sampling-based tolerance-cost optimization, a combination of statistical tolerance analysis based on sampling techniques and metaheuristic optimization algorithms, enables an automated and optimal allocation of tolerance values and, thus, solves the conflict of objectives between costs and quality. However, limitations in effectiveness and efficiency still prevent its profitable application for solving complex, industry-relevant problems and exploiting hidden cost potentials. To close the current research gaps, the individual methods involved, in particular the sampling, non-conformance rate estimation and surrogate model-based optimization, are (further) developed and harmonized in one common approach, ensuring that reliable optimization results can be obtained in adequate computing times. Its extension to simultaneous machine selection and allocation with different batch sizes and selective assembly, considering machine-specific part tolerance distributions and geometrical, mutually dependent tolerances, significantly expands the context of use to practical aspects. A final evaluation of the developed framework proves its potential for a profitable application to practical problems and serves to identify further research potentials.<br

Sampling-basierte Toleranz-Kosten-Optimierung - Eine optimierungsbasierte Methode zur Vergabe kostenminimaler Toleranzen - Hallmann, Martin; Schleich, Benjamin; Wartzack, Sandro (WiGeP News, 2020)

Scenario analysis and potential identification to structure of the roadmap to autonomous design - Dworschak, Fabian; Schleich, Benjamin; Wartzack, Sandro (11th Graz Symposium VIRTUAL VEHICLE, 2018)
In the long term, the cooperation between the central department for IT services of the AUDI AG and the institute of engineering design of the Friedrich-Alexander University aims for integration autonomous design in the deployment of virtual vehicles. To structure this task, a roadmap showing and arranging the upcoming steps is necessary similar to the roadmap towards autonomous driving. However, integration and deployment of data-driven solutions into the development processes differs widely to driving. First, the grade of automation is not homogenous across the development processes. Second, identifying useful solutions to a given task in the design process is difficult. This paper aims to answer the question how to bridge the gap between theoretical models for data-driven solutions and the deployment of these models in t
Keywords: Continuous integration and deployment of data and models; Model-based systems engineering; AI in vehicle development; testing; and operation

Schadens- und Ausfallmechanismen bei Wälzlagern unter Schwenkbewegungen - Halmos, Fabian; Bartz, Marcel; Wartzack, Sandro (15. VDI-Fachtagung „Gleit- und Wälzlagerungen 2023", 2023)

Schadens- und Ausfallmechanismen bei Wälzlagern unter Schwenkbewegungen - Halmos, Fabian; Bartz, Marcel; Wartzack, Sandro (Gleit- und Wälzlagerungen 2023, 2023)
Rolling bearings under oscillating motion are used in a wide range of applications. However, there are no validated calculation methods for calculating the rating life for this application. Instead, the oscillating motions are usually converted into continuous revolutions and then designed according to DIN ISO 281 or DIN 26281. Alternatively, one of the existing, but not validated, calculation approaches for non-continuous revolutions can be used. However, especially for small oscillations, it is unclear to what extent these calculation approaches are valid at all, since wear can occur here as a failure mechanism instead of fatigue. The aim of this paper is therefore to provide an understanding of possible failure mechanisms in oil-lubricated rolling bearings under small oscillating motions. For this purpose, several life tests are carried out and evaluated with a new type of rolling bearing oscillation test rig. Based on the damage that occurs, a statement can be made about the failure mechanisms under
CRIS-Team Scopus Importer:2023-12-08

Segmentation of musculotendinous structures of the hip from 3d imaging for patient-specific individualization of biomechanical simulations - Fleischmann, Christopher; Scherb, David; Leher, Irina; Wolf, Alexander; Miehling, Jörg; Wartzack, Sandro; Sesselmann, Stefan (Advances in Intelligent Systems and Computing, 2021)
Due to a steady increase of total hip arthroplasty, biomechanical multibody simulations are moving more and more into focus. These simulations allow to calculate forces, moments and muscle activities in the human body and, thus, can help to improve surgery planning and outcomes. However, generic human body models based on anthropometric data are mostly used for these simulations. Since these models are not customized to patients, there is a need to adapt the models to the individual patient. Therefore, 3D models of bones are created by segmentation of CT and MRI scans and assigned different landmarks. This allows to define both, the shape and size of bones, in this case the femur, which leads to patient-specific adjustments of muscle attachment points. Also muscles can be segmented to determine important parameters such as muscle volume, allowing the definition of important simulation parameters, like the maximum isometric force or the tendon slack length of individual patients leading to customized models.
CRIS-Team Scopus Importer:2020-08-28
Keywords: Biomechanics; Multibody simulation; Muscle function; Muscle segmentation; Orthopaedics; Subject-specific modeling and simulation; Surgery planning; Total hip arthroplasty

Semantic Support for Engineering Design Processes - Breitsprecher, Thilo; Codescu, Silvestru Mihai; Schröder, Lutz; Wartzack, Sandro; jucovschi, Constantin; Kohlhase, Michael (In Proc. 13th International Design Conference, DESIGN 2014, 2014)
UnivIS-Import:2015-04-17:Pub.2014.tech.IMMD.profes_1.semant
Keywords: design knowledge; ontology; semantics in product development

Sensitivitätsanalyse der tribologischen Eigenschaften gefräster Oberflächenstrukturen bei der Blechmassivumformung - Breitsprecher, Thilo; Hense, Rouven; Beyer, Florian; Biermann, Dirk; Wartzack, Sandro; Willner, Kai (Tagungsband zum 2. Erlanger Workshop Blechmassivumformung 2013, 2013)
Reibeigenschaften von Oberflächen für Umformwerkzeuge gezielt einzustellen (Tailored Friction) nimmt bei der Entwicklung moderner Umformprozesse in technischer und ökonomischer Hinsicht eine zentrale Rolle ein. Dies betrifft insbesondere die Blechmassivumformung, die im Rahmen des SFB Transregio 73 erforscht wird. Ein neues Verfahren, das im SFB entwickelt wird, ist die Strukturierung durch regenerative Werkzeugschwingungen beim Fräsen. Ziel dabei ist es, einen separaten Prozessschritt, in dem nur strukturiert wird, einzusparen. Beim Fräsen mit Werkzeugschwingungen ist aufgrund der hohen Komplexität eine simulationsgestützte Auslegung unentbehrlich. Realitätsnahe Ergebnisse können dabei nur durch eine hinreichend gute Parametrisierung der Simulation erzielt werden, was im Besonderen für die Zerspankraftparameter gilt. In diesem Artikel wird die Sensitivität von tribologisch relevanten Kenngrößen auf die Zerspankraftparameter mit dem Ziel diskutiert, eine Aussage über die notwendige Güte zu treffen, mit der diese ermittelt werden müssen, um die Reibeigenschaften gefräster Oberflächen zuverlässig vorhersagen zu können. Um aus den simulierten gefrästen Oberflächen tribologische Kennwerte zu ermitteln, die für die Blechmassivumformung mit ihren hohen Flächenpressungen realitätsnah sind, findet ein Halbraummodell Anwendung.
Keywords: Tailored Friction; Sensitivitätsanalyse; Knowledge Discovery in Databases

Sensitivity Analysis of features in tolerancing based on constraint function level sets - Ziegler, Philipp; Wartzack, Sandro (Reliability Engineering & System Safety, 2015)
Usually, the geometry of the manufactured product inherently varies from the nominal geometry. This may negatively affect the product functions and properties (such as quality and reliability), as well as the assemblability of the single components. In order to avoid this, the geometric variation of these component surfaces and associated geometry elements (like hole axes) are restricted by tolerances. Since tighter tolerances lead to significant higher manufacturing costs, tolerances should be specified carefully. Therefore, the impact of deviating component surfaces on functions, properties and assemblability of the product has to be analyzed. As physical experiments are expensive, methods of statistical tolerance analysis tools are widely used in engineering design. Current tolerance simulation tools lack of an appropriate indicator for the impact of deviating component surfaces. In the adoption of Sensitivity Analysis methods, there are several challenges, which arise from the specific framework in tolerancing. This paper presents an approach to adopt Sensitivity Analysis methods on current tolerance simulations with an interface module, which bases on level sets of constraint functions for parameters of the simulation model. The paper is an extension and generalization of Ziegler and Wartzack [1]. Mathematical properties of the constraint functions (convexity, homogeneity), which are important for the computational costs of the Sensitivity Analysis, are shown. The practical use of the method is illustrated in a case study of a plain bearing.
UnivIS-Import:2015-10-26:Pub.2015.tech.FT.FT-KLMEFK.sensit
Keywords: Computer-aided tolerancing; Design features; Deviation Domain; Sensitivity Analysis

Sensor selection and integration for Cyber-Physical Systems in context of Digital Twins – A systematic review of requirements - Fett, Michel; Wilking, Fabian; Götz, Stefan; Kirchner, Eckhard; Wartzack, Sandro (2023 18th Annual System of Systems Engineering Conference (SoSe), 2023)
Digital Twins process real-time data collected from a Physical Twin. This real-time data is often measurement by sensors, which must be selected and integrated during the development or modification of the physical twin. In this paper, a systematic literature review on sensors for Digital Twins and Cyber-Physical Systems is conducted. The results are mapped into a framework for selection and integration. From this, the special requirements for the sensors that arise from the use of Digital Twins can be identified.<br

Shaping the digital twin for design and production engineering - Schleich, Benjamin; Anwer, Nabil; Mathieu, Luc; Wartzack, Sandro (CIRP Annals - Manufacturing Technology, 2017)
The digitalization of manufacturing fuels the application of sophisticated virtual product models, which are referred to as digital twins, throughout all stages of product realization. Particularly, more realistic virtual models of manufactured products are essential to bridge the gap between design and manufacturing and to mirror the real and virtual worlds. In this paper, we propose a comprehensive reference model based on the concept of Skin Model Shapes, which serves as a digital twin of the physical product in design and manufacturing. In this regard, model conceptualization, representation, and implementation as well as applications along the product life-cycle are addressed.
Keywords: Design; Tolerancing; Digital twin

Sheet-bulk Metal Forming a New Process for the Production of Sheet Metal Parts with Functional Components - Schaper, M.; Lizunkova, Y.; Vucetic, M.; Cahyono, T.; Hetzner, Harald; Opel, Simon; Schneider, J.; Koch, T.; Plugge, B. (Metallurgical and Mining Industry, 2011)
The first results of different new sheet-bulk forming methods are presented in the article. It is shown how an additional superimposing of oscillation can be attached to the forming punch in order to improve the forming limit of the sheet material. New coating and atmospheric plasma-nitriding methods for processing of the forming tools (for improving of hardness and wear resistance) are also represented in the article. © Metallurgical and Mining Industry, 2011.
UnivIS-Import:2015-03-09:Pub.2011.tech.FT.FT-KLMEFK.sheetb
Keywords: Atmospheric plasma-nitriding; Pvd/pacvd coatings; Reduce the forming forces; Sheet-bulk metal forming

Shifting value stream patterns along the product lifecycle with digital twins - Schleich, Benjamin; Dittrich, Marc André; Clausmeyer, Till; Damgrave, Roy; Erkoyuncu, John Ahmet; Haefner, Benjamin; de Lange, Jos; Plakhotnik, Denys; Scheidel, Wieben; Wuest, Thorsten (Procedia CIRP, 2020)
The concept of digital twins promises high potentials for product design, manufacturing, user experience and recycling. Thus, digital twins have received increasing interest in academia and industry. However, the actual benefits of digital twins remain in many cases unclear. This article aims to summarize selected recent developments in this field and demonstrate use cases from different phases of the product lifecycle. For that purpose, examples from the design, manufacturing, use and recycling phase are presented. In a subsequent discussion, ideas for new value stream patterns using digital twins are envisioned and research questions are derived.
CRIS-Team Scopus Importer:2020-03-27
Keywords: Cyber-physical systems; Design; Digital twin; Manufacturing; Recycling

Simplified integrative simulation of short fibre reinforced polymers under varying thermal conditions - Witzgall, Christian; Wartzack, Sandro (10th European LS-DYNA Conference - Book of Abstracts, 2015)
The use of injection moulded, short fibre reinforced structural parts in vehicle design is increasing due to their low density and outstanding mechanical properties. As the distribution and orientation of fibres within the components are heavily dependent on the moulding process, product developers do well to take process simulations into consideration before performing anisotropic structural analyses. To enable the use of these integrative simulations within early design stages, a simplified approach has been developed by Schöpfer [2] and extended by Gruber/Wartzack [1]. It considers the material's anisotropy by using the fibre orientation data gained from the injection moulding simulation. By reducing the complexity of the orientation condition and the material representation, a simulation approach suitable for early design stages was created. However, within the so-called IS4ED approach by Gruber the influence of high or low temperatures on the material behaviour is not considered. As the thermoplastic materials are sensitive to even minor changes in temperature, the IS4ED approach has to be enhanced. The decrease of stiffness and maximum stress levels and the increase of maximum strain at elevated temperatures have to be added to the approach. Nevertheless, the reduced complexity and suitability for early design steps, which are the main advantages, shall remain untouched. The material behaviour within the enhanced IS4ED approach will still be modelled by overlapping different material descriptions. In addition to the layers covering the anisotropic and strain-rate dependent behaviour, the definition of new layers to describe temperature dependency will be introduced in this paper. This will enable to predict the structural behaviour in a wide temperature range.
Keywords: Simulation; SFRP

Simplified simulation of aluminum-CFRP adhesive joints - Wartzack, Sandro; Witzgall, Christian; Kellermeyer, Markus; Most, Thomas (RDO-Journal, 2016)

Simplifying Computer Aided Ergonomics: A User-Product Interaction-Modeling Framework in CAD Based on a Taxonomy of Elementary Affordances - Wolf, Alexander; Wagner, Yvonne; Oßwald, Marius; Miehling, Jörg; Wartzack, Sandro (IISE Transactions on Occupational Ergonomics and Human Factors, 2021)
OCCUPATIONAL APPLICATIONS
CRIS-Team WoS Importer:2021-07-09

Simplifying Ergonomic Assessment for Designers: A User-Product Interaction-Modelling Framework in CAD - Wolf, Alexander; Wagner, Yvonne; Oßwald, Marius; Miehling, Jörg; Wartzack, Sandro; Wolf, Alexander; Wagner, Yvonne; Oßwald, Marius; Miehling, Jörg; Wartzack, Sandro (Proceedings of the 21st Congress of the International Ergonomics Association (IEA 2021), 2021)
Digital human models have not yet reached their full potential for proactive virtual assessment of ergonomics in engineering and industrial design. Especially the modelling of interaction between user and product often is time demanding, cumbersome, unstandardized and embedded insufficiently in the computer-aided engineering environment. On the one hand, the interaction modelling needs to be applicable for a majority of products and shall contain as much a-priori knowledge regarding human behavior as possible. On the other hand, the method needs to be appropriate for designers, without special ergonomic expertise or human behavior training. In this contribution, we present an interaction-modelling framework based on the concept of affordances, which ought to resolve these partly contradictable demands. Hence, 31 elementary affordances, describing fundamental physical interaction possibilities between human end effectors and rudimental (product) geometries, were deduced using a classification method. The elementary affordances shall serve as a medium for interaction modeling. For this purpose, we introduce an interaction modelling routine, implemented in a CAD system, which makes use of the identified elementary affordances in terms of CAD-features. Those enable designers to apply interaction possibilities directly to a CAD-model in order to define the constraints for a DHM simulatio
CRIS-Team Scopus Importer:2021-08-13
Keywords: User product interaction; Digital human models; Affordance; CAD; Interaction modelling

Simulation-based development of Pareto-optimized tailored blanks for the use within sheet-bulk metal forming - Küstner, Christof; Beyer, Florian; Kumor, Dustin; Loderer, Andreas; Wartzack, Sandro; Willner, Kai; Blum, Heribert; Rademacher, Andreas; Hausotte, Tino (DS 84: Proceedings of the DESIGN 2016 14th International Design Conference, 2016)
In the context of lightweight design, the so-called tailored blanks are more frequently used to improve sheet-bulk metal forming process results. In order to meet the requirements of tailored blank designs for subsequent sheet-bulk metal forming process steps, design engineers can influence many process or geometry parameters. A crucial task for design engineers is to find the optimal process and geometry parameter setting that is an optimal design with respect to multiple design requirements. A simulation-based approach to face this challenge is presented in this pape
Keywords: pareto-optimized design; simulation study; friction law

Simulation based generation of an initial design taking into account geometric deviations and deformations - Walter, Michael; Breitsprecher, Thilo; Gruber, Georg; Wartzack, Sandro (Proceedings of the 18th International Conference on Engineering Design 2011 (ICED11), 2011)
The success of a product's development is essentially affected by its functionality. So the product developer has to ensure the functionality as early as possible. Since this usually can't be achieved with the first design several iterations are needed to modify the design. The product's functionality depends largely on the interaction of its components and their geometries. So geometric deviations of these components need to be taken into account. These deviations can result e.g. from manufacturing discrepancies or being operation-depending like deformations. This paper presents an approach which enables the product developer to determine an initial design proposal that fulfils its function. So no time- and money-consuming iterations are needed. Therefore the approach uses methods and tools like tolerance allocation, topology optimization and parameter optimization at an early stage. The tolerance allocation is needed to define the functional requirement of the non-ideal components. The optimization tools are used to create the initial design proposal fulfilling the functional requirement. A case study of a non-ideal scissor-type lift table illustrates the approach.
UnivIS-Import:2015-04-16:Pub.2011.tech.FT.FT-KLMEFK.simula
Keywords: Early functional validation; Initial design proposal; Non-ideal parts; Topology optimization

Simulation elastohydrodynamischer Wälz-/Gleit-Kontakte mit Oberflächenstrukturen durch kommerzielle FE-Programme - Weschta, Martin; Tremmel, Stephan; Wartzack, Sandro (Wissenschaftliches Kolloquium Wälzlager, 2015)

Simulation in Human-Centered Design - Past, Present and Tomorrow - Miehling, Jörg; Krüger, Daniel; Wartzack, Sandro (Smart Product Engineering - Proceedings of the 23rd CIRP Design Conference, 2013)
Due to the ever rising significance of the products’ usability the consideration of the user in the product development process becomes more and more important to stay competitive. This paper firstly outlines the historical evolution of how user-product relationships have been investigated and considered in product design in the past. A literature research has been conducted to acquire information about the state of the art in the multidisciplinary field of human-centered design as well as to derive which challenges towards a virtual assessment of human-related product properties exist. Finally the most recent research activities aiming to solve the identified issues as well as future prospects in simulating human-product interactions are presented.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.simula
Keywords: human-centered design; ergonomics; simulation; virtual product development; digital human modeling; biomechanics; hybrid mock-up