TY - CHAP A1 - Galka, Stefan A1 - Meißner, Sebastian T1 - Simulation-Based Digital Twins for Internal Transport Systems T2 - Procedia Computer Science N2 - The increasing complexity of internal transport systems in industrial applications poses significant challenges for operational decision-making. This paper presents a simulation-based Digital Twin framework developed within the research project TwinTraSys to support the control of such systems. The framework is specifically tailored to the constraints of real-world IT infrastructures, requiring minimal transaction data, while enabling predictive analysis and dynamic scenario evaluation. It consists of a modular architecture divided into four core components: data provision, data preparation, simulation, and decision support. A dedicated simulation framework enables the automated generation of structural models and the integration of real-world operational control systems. The proposed approach has been validated in industrial settings and has demonstrated its ability to support resource planning and transport resource allocation through simulation-based experimentation and multi-criteria evaluation. This paper contributes to the practical advancement of Digital Twin applications in intralogistics by bridging the gap between theoretical models and real-world constraints. KW - Digital Twin KW - Intralogistics KW - Logistics KW - Operational Control KW - Simulation KW - Simulation-based Decision Support Y1 - 2025 U6 - https://doi.org/10.1016/j.procs.2025.12.016 N1 - Corresponding author der OTH Regensburg: Stefan Galka VL - 274 SP - 161 EP - 170 PB - Elsevier ER - TY - CHAP A1 - Saffert, Anne-Sophie A1 - Wiederer, Jonas A1 - Höng, Simon A1 - Linner, Thomas A1 - Obergrießer, Mathias A1 - Neumann, Patrick T1 - Towards AI-based optimization of human-centered and robot-assisted construction processes T2 - Proceedings of the 42nd International Symposium on Automation and Robotics in Construction (ISARC), Montreal, Canada July 28-31, 2025 N2 - This research explores an innovative AI-driven approach to optimizing construction processes with a focus on humancentered design, addressing key challenges in the construction industry, such as skilled labor shortages and ergonomic risks associated withwork-related musculoskeletal disorders. By integrating process design with AI-based algorithms into simulation tools, various construction process layout variants including robot-assisted scenarios can be simulated and evaluated based on user-specific key performance indicators (e.g., ergonomic score, layouting parameters) to identify optimized solutions. A data processing algorithm automates the process, eliminating the need for manual simulation variations and resulting in increased operational productivity. The AI-based system evaluates and optimizes process layouts by adjusting control parameters. A case study on a brick laying process serves as an exemplary use case, highlighting the necessity and impact of adopting process optimization. The findings emphasize the transformative potential of automated process optimization within simulation environments to rethink existing construction practices, enhance worker well-being, and boost operational productivity. KW - AI-based Learning KW - Simulation KW - Process optimization KW - Human Factors KW - Parametric Design Automation Y1 - 2025 SN - 978-0-6458322-2-8 U6 - https://doi.org/10.22260/ISARC2025/0112 SN - 2413-5844 N1 - Präsentationsvideo: https://www.youtube.com/watch?v=QL-1mIuy-_M SP - 861 EP - 868 PB - IAARC ER - TY - CHAP A1 - Schaeffer, Leon A1 - Schmaußer, Theresa A1 - Herrmann, David A1 - Lehmann, Lukas A1 - Dendorfer, Sebastian A1 - Böhm, Valter T1 - Multi-Body Simulation of a Dynamic Hand Orthosis based on a Prestressed Compliant Structure Incorporating the Human Hand T2 - 2025 International Symposium on Medical Robotics (ISMR), May 14-16, 2025, Atlanta, GA, USA, N2 - Many dynamic hand orthoses use one degree of freedom joints, such as hinge joints. Therefore, these orthoses can only partially replicate the complex, multi-axis movement of the hand. A possible solution for this is the use of prestressed compliant structures as the basis for orthoses. Determining the joint forces in the wrist and optimizing the dynamic orthosis to influence these forces as well as acting muscle forces are important steps in the development of these orthoses. For this reason, in this work multi-body simulation models of an orthosis with human hand models are presented. Based on these theoretical investigations, more detailed orthosis models as well as initial prototypes of prestressed compliant dynamic hand orthoses can be developed. KW - Hands KW - Wrist KW - Systematics KW - Simulation KW - Dynamics KW - Refining KW - Prototypes KW - Usability KW - Research and development KW - Testing Y1 - 2025 U6 - https://doi.org/10.1109/ISMR67322.2025.11025982 SP - 80 EP - 86 PB - IEEE ER - TY - CHAP A1 - Galka, Stefan A1 - Meißner, Sebastian A1 - Obermeir, Theresia ED - Fottner, Johannes T1 - Digitale Zwillinge für die Steuerung innerbetrieblicher Transportsysteme T2 - 32. Deutscher Materialfluss-Kongress 2025, Garching bei München, 20.-21.3.2025 N2 - Im Rahmen des Forschungsprojektes "Digitale(r) Zwillinge zur dynamischen Simulation für die Planung und Steuerung innerbetrieblicher Transportsysteme im Rahmen der digitalen Fabrik" (TwInTraSys) wurde ein simulationsbasierter Digitaler Zwilling zur vorausschauenden Entscheidungsunterstützung im operativen Betrieb von innerbetrieblichen Transportsystemen entwickelt. Das Konzept wurde demonstratorisch umgesetzt und bei verschiedenen Anwendungsunternehmen getestet und validiert. Im Folgenden werden die Einsatzmöglichkeiten im Zentrallager der Firma HiPP am Beispiel einer Ressourceneinsatzplanung dargestellt. KW - Innerbetrieblicher Transport KW - Simulation KW - Digitale Zwillinge Y1 - 2025 PB - VDI-Verlag ER - TY - CHAP A1 - Dilefeld, Maximilian A1 - Claus, Thorsten A1 - Teich, Enrico T1 - Robot Task Assignment In Dynamic Factory Environments T2 - Proceedings of the 38th ECMS International Conference on Modeling and Simulation (ECMS 2024): June 4th - June 7th, 2024, Cracow, Poland N2 - Automated Guided Vehicles (AGVs) and Autonomous Mobile Robots (AMRs) are being applied more and more frequently in a wide range of use cases. Following the general trend of decentralisation of control structure in the Industry 4.0 paradigm, this paper analyses the application of auction algorithms to solve the robot task assignment problem. We focus on the use of mobile robots in production environments with a high level of uncertainty which places hight demand on the flexibility of the online scheduling architecture. A sequential single-item (SSI) auction algorithm is validated for a real-world use case where multiple mobile robots supply car bodies to manual rework stations in a paint shop application using simulation. The optimization objective of such an algorithm is discussed in regards to the examined use case. KW - Mobile Robots KW - Auction KW - Simulation Y1 - 2024 SN - 978-3-937436-84-5 U6 - https://doi.org/10.7148/2024-0338 SN - 2522-2422 SP - 338 EP - 344 PB - ECMS ER - TY - CHAP A1 - Terbrack, Hajo A1 - Claus, Thorsten A1 - Herrmann, Frank T1 - Emission reduction through production scheduling by priority rules and energy onsite generation T2 - Proceedings of the 36th ECMS International Conference on Modelling and Simulation (ECMS 2022), May 30th - June 3rd, 2022, Ålesund, Norway N2 - This article describes primary findings of various simulation runs on job shop scheduling dealing with energy consumption and emission pollution. By two combinations of priority rules, production is linked to the generation output of a renewable energy source installed onsite. The resulting schedules show a reduction of energy-related emissions and makespan compared to several conventional priority rules often used in industrial practice. KW - Sustainable Production Planning KW - Energy-related Emissions KW - Job Shop Scheduling KW - Simulation Y1 - 2022 SN - 978-3-937436-77-7 U6 - https://doi.org/10.7148/2022-0114 SN - 2522-2414 SP - 114 EP - 120 PB - ECMS ER - TY - GEN A1 - Herrmann, Frank A1 - Dilefeld, Maximilian T1 - Improving the scheduling of AGV and AMR using simulation T2 - OR23, International Conference on Operations Research, August 29 to September 1, 2023, Hamburg N2 - Automated Guided Vehicles (AGV) and intelligent Autonomous Mobile Robots (AMR) are an important tool for designing a flexible Industry 4.0 shopfloor. Both types of Mobile Robots are usually deployed with a Fleet Management software to manage (transport) orders and vehicles together with other superordinate control systems. The planning tasks in the superordinate control system used by both AGVs and AMRs can be divided into Material Flow Management, Job Management, Vehicle Dispatching and Job Processing. Requests for supply and removal of material is issued by the stations and has to be combined to transport jobs. Alternatively, more complex system often user external Material Flow Controllers (e.g. MES). Jobs are collected in a queue and their execution order is determined. Vehicles which can execute the next job have to be identified and the best one is selected. Jobs are split into smaller tasks which are sent to the Mobile Robot and executed. For AGVs navigation functions are mostly integrated into the Fleet Manager as part of the Job Processing, while AMRs perform lower-level navigation functions directly on the vehicle and use the superordinate control system for implementing restrictions and traffic control functions. A need for further research and development was identified especially for decision-making algorithms within the Fleet Management. The goal is to compare existing and develop new strategies to solve the different planning problems. For the individual planning tasks different techniques have been discussed and used in research and practice. However, there is no universal best solution and different options must be compared in the context of the specific use case. KW - Simulation KW - Automated Guided Vehicles KW - Autonomous Mobile Robots Y1 - 2023 ER - TY - JOUR A1 - Kral, Christian A1 - Haumer, Anton A1 - Kapeller, Hansjörg A1 - Pirker, Franz T1 - Design and Thermal Simulation of Induction Machines for Traction in Electric and Hybrid Electric Vehicles JF - World Electric Vehicle Journal N2 - An electric traction machine for an electric or a hybrid electric vehicle is usually designed for a specific operating point or cycle. For such an operating point or cycle, the masses and the cooling circuit of the electric machine determine the time dependent temperature distribution within the machine. For a specific load cycle, the thermal simulation of the machine can reveal possible mass and size reductions for a given insulation class of the machine. In addition, such simulations allow the comparison of various cooling concepts. In the machine design process, the first step is a conventional electromagnetic machine design. From the geometric data of this design and the material properties, the parameters of a thermal equivalent circuit can be derived. The differential and algebraic equations of the thermal equivalent circuit are solved by a simulation tool to predict the temperatures of the critical parts in the electric machine. A thermal equivalent circuit is accurate enough to predict the thermal behavior of the critical parts in the electric machine, and yet not too complex, to obtain simulation results with moderate numerical effort. This enables an iterative design process to optimize the drive. KW - Induction Motor KW - Electric Drive KW - Modeling KW - Simulation KW - Thermal Management Y1 - 2007 U6 - https://doi.org/10.3390/wevj1010190 SN - 2032-6653 VL - 1 IS - 1 SP - 190 EP - 196 PB - MDPI ER - TY - CHAP A1 - Ulreich, Fabian A1 - Moser, Elisabeth A1 - Olbrich, Florian A1 - Ebert, Martin A1 - Bierl, Rudolf A1 - Kaup, André ED - Keil, Rudolf ED - Tschorn, Jan Alexander ED - Tümler, Johannes ED - Altinsoy, Mehmet Ercan T1 - Luminance Simulation in CARLA under Cloud Coverage - Model Validation and Implications T2 - 2023 IEEE International Workshop on Metrology for Automotive (MetroAutomotive), -30 June 2023, Modena, Italy N2 - To decrease the number of kilometers driven during the development of autonomous cars or driving assistance systems, performant simulation tools are necessary. Currently, domain distance effects between simulation and reality are limiting the successful application of rendering engines in data-driven perception tasks. In order to mitigate those domain distance effects, simulation tools have to be as close to reality as possible for the given task. For optical sensors like cameras, the luminance of the scene is essential. We provide within this paper a method to measure the luminance of rendered scenes within CARLA, an often used open-source simulation environment. Thereby, it is possible to validate the environment and weather models by taking real-world measurements with photometric sensors or with the help of open-source weather data, published e.g. by the German federal service for weather data (DWD - "Deutscher Wetterdienst"). Employing our proposed luminance measurement, the domain gap resulting from the simulation can be specified, which makes it possible to evaluate the statements about the safety of the automated driving system determined within the simulation. We show that the ratio between global and diffuse radiation modeled by the default atmosphere models within CARLA are under limited conditions similar to real-world measurements taken by the DWD. Nevertheless, we show, that the ratio’s temporal variability in real-world situations is not modeled by CARLA. KW - Atmospheric measurements KW - Atmospheric modeling KW - Cameras KW - carla KW - Cloud computing KW - cloud coverage KW - Data models KW - luminance KW - meteorology KW - Simulation KW - Soft sensors KW - weather KW - Wind Y1 - 2023 SN - 979-8-3503-2187-6 U6 - https://doi.org/10.1109/MetroAutomotive57488.2023.10219098 SP - 228 EP - 233 PB - IEEE ER - TY - BOOK A1 - Rill, Georg A1 - Schaeffer, Thomas A1 - Borchsenius, Fredrik T1 - Grundlagen und computergerechte Methodik der Mehrkörpersimulation BT - Vertieft in Matlab-Beispielen, Übungen und Anwendungen N2 - Dieses Lehr- und Übungsbuch vermittelt auf anschauliche Weise die Methoden der Mehrkörpersimulation und verdeutlicht deren Vor- und Nachteile bei der praktischen Anwendung anhand konkreter Beispiele. Die einzelnen Methoden werden durch Matlab-Skripte und -Funktionen verdeutlicht, wobei die Modellbildung, die mathematische Beschreibung und die numerische Simulation von Systemen starrer Körper die Schwerpunkte bilden. Die vorliegende Auflage wurde unter anderem um Matlab-Live-Skripte erweitert, welche kleine Animationen zur Veranschaulichung der Dynamik der Probleme enthalten. Die Lösungen zu den Übungsbeispielen und die integrierten Matlab-Skripte sowie weitere Beispiele und Anwendungen stehen über QR-Codes zum Download zur Verfügung und ermöglichen dadurch auch ein effizientes Selbststudium. KW - ADAMS-Modell KW - McPherson-Achse KW - Euler-Parameter KW - Bushings KW - Kontaktelement KW - Kinematische Bindung KW - Räumliches Doppelpendel KW - Analyse MKS KW - Lumped Mass Modelle KW - SIMPACK-Modell KW - Sparse Matrix KW - Mehrkörpersystem KW - MATLAB KW - Dynamik KW - Simulation Y1 - 2023 U6 - https://doi.org/10.1007/978-3-658-41968-4 PB - Springer Nature ER - TY - CHAP A1 - Galka, Stefan A1 - Schuhegger, Lukas ED - Feng, B. ED - Pedrielli, G. ED - Peng, Y. ED - Shashaani, S. ED - Song, E. ED - Corlu, C.G. ED - Lee, L.H. ED - Chew, E.P. ED - Roeder, T. ED - Lendermann, P. T1 - Integration of Discrete-event Simulation in the Planning of a Hydrogen Electrolyzer Production Facility T2 - Proceedings of the 2022 Winter Simulation Conference (WSC), 11-14 Dec. 2022, Singapore N2 - In the context of production and factory planning, the expansion of the factory must already be taken into account during initial planning. This results in an increase in planning complexity, as the involved planners have to know the expansion stages of the factory in the different time periods and have to evaluate concept modifications across all time periods. This paper presents an idea for a planning tool, which takes expansion stages into consideration. The data model contains all relevant information to generate a simulation model of the factory in an almost automated way. The aim is to enable factory planners to quickly investigate concept changes with the help of simulation, for example, to identify bottlenecks. KW - Simulation KW - Production KW - Digital Twin Y1 - 2022 UR - https://informs-sim.org/wsc22papers/pos114.pdf PB - IEEE CY - Singapore ER - TY - CHAP A1 - Haimerl, Simon A1 - Tschernitz, Christoph A1 - Schiller, Tobias A1 - Weig, Christoph A1 - Briem, Ulrich A1 - Galka, Stefan T1 - Development of a Simulation Framework for Urban Ropeway Systems and Analysis of the Planned Ropeway Network in Regensburg, Germany T2 - Proceedings of the 2022 Winter Simulation Conference (WSC), 11-14 Dec. 2022, Singapore N2 - To evaluate the performance of a ropeway in an urban environment, simulations of the dynamic passenger transport characteristics are required. Therefore, a modular simulation model for urban ropeway networks was developed, which can be flexibly adapted to any city and passenger volume. This simulation model was used to analyze the ropeway network concept of the German city Regensburg and to determine the expected operating conditions. The passenger volume, different types of persons, their occurrence probability and their destination distribution is depending on the location and daytime and can be defined for each individual station. In an initial analysis, the number of passengers currently occurring in bus traffic were projected onto the ropeway network. To enable climate-friendly and efficient operation, different strategies were developed to significantly reduce the number of gondolas. The best fitting strategies resulted in significant cost savings while passenger comfort, as represented by queue time, remained unchanged. KW - Simulation KW - urban mobility KW - ropeway Y1 - 2022 SN - 978-1-6654-7661-4 U6 - https://doi.org/10.1109/WSC57314.2022.10015510 SP - 1413 EP - 1424 PB - IEEE ER - TY - CHAP A1 - Schmid, Florian A1 - Wild, Tobias A1 - Schneidewind, Jan A1 - Vogl, Tobias A1 - Schuhegger, Lukas A1 - Galka, Stefan T1 - Simulation Based Approach for Reconfiguration and Ramp up Scenario Analysis in Factory Planning T2 - Proceedings of the 2022 Winter Simulation Conference (WSG), 11-14 Dec. 2022, Singapore N2 - Structural changes in production entail a potential economic risk for manufacturing companies. It is necessary to identify a suitable strategy for the reconfiguration process and to continue to meet the demand during the change in the factory structure and ramp-up phase. A simulation offers the possibility to analyze different ramp-up scenarios for the factory structure and to select a suitable concept for the reconfiguration process. A discrete event simulation approach is presented that can be used to evaluate variants of structural changes and serves as a basis for deciding on a reconfiguration strategy. This approach is demonstrated using a specific production step of a plant producing hydrogen electrolyzers, the results and generalized conclusions are discussed. KW - Simulation KW - Production KW - Ramp up Y1 - 2022 SN - 978-1-6654-7661-4 U6 - https://doi.org/10.1109/WSC57314.2022.10015310 SP - 2842 EP - 2852 PB - IEEE ER - TY - CHAP A1 - Galka, Stefan T1 - Untersuchung von Auftragsfreigabestrategien für mehrzonige Kommissioniersysteme im Online-Lebensmittelhandel T2 - ASIM SST 2022 Proceedings Langbeiträge, 26. ASIM Symposium Simulationstechnik: 25.07.-27.07.2022, TU Wien N2 - This paper briefly presents the challenges for order control and release of multi-zone order picking systems. On the one hand, the order control must ensure that all orders are processed on time, and on the other hand, the space requirements (buffer) and the utilisation of the zones must be considered. Within the framework of a case study, different strategies for order release were developed. The paper shortly describes the ideas of the strategies and presents results of a case-based simulative evaluation of the strategies. The findings of the simulation study are the basis for the development of a digital twin for the operational control of multi-zone picking systems. KW - Simulation KW - Kommissionierung KW - Simulation KW - Logistik KW - Planung Y1 - 2022 SN - 978-3-901608-97-1 U6 - https://doi.org/10.11128/arep.20.a2021 VL - 2022 SP - 23 EP - 30 PB - ARGESIM Verlag CY - Wien ER - TY - JOUR A1 - Galka, Stefan A1 - Follath, Alexander A1 - Bross, Florian ED - Bauer, Wilhelm ED - Volk, Wolfram ED - Zäh, Michael T1 - Vorgehensmodell zur Erstellung Digitaler Zwillinge für Produktion und Logistik JF - Zeitschrift für wirtschaftlichen Fabrikbetrieb N2 - Der Digitale Zwilling (DZ) ist ein wichtiger Bestandteil der Industrie 4.0 und ermöglicht Anwendungen wie Predictive Maintenance, virtuelles Prototyping oder die Steuerung von Produktions- und Logistikprozessen. Herausforderungen bei der Entwicklung des Digitalen Zwillings entstehen durch fehlende Struktur und Standards. Mit diesem Beitrag soll ein Vorgehensmodell für die Erstellung eines Digitalen Zwillings im Bereich der Produktion und Logistik aufgezeigt werden. Das Vorgehensmodell hilft bei der Einordnung, für welche Anwendungsfälle ein Digitaler Zwilling entwickelt werden kann, welche Schritte bei einer Umsetzung erfolgen müssen, und gibt einen Überblick über die Voraussetzungen und Komplexität bei der Entwicklung. Das zentrale Element bildet dabei die zielgerichtete Aufbereitung und Analyse der zugrunde liegenden Daten mittels des in der Industrie etablierten Vorgehensmodell CRISP-DM. KW - Digitale Zwillinge KW - Simulation KW - Logistik KW - Produktion Y1 - 2022 U6 - https://doi.org/10.1515/zwf-2022-1127 VL - 117 IS - 11 SP - 691 EP - 696 PB - De Gruyter CY - Berlin ER - TY - JOUR A1 - Moser, Elisabeth A1 - Jobst, Simon A1 - Bierl, Rudolf A1 - Jenko, Frank T1 - A Deep Learning System to Transform Cross-Section Spectra to Varying Environmental Conditions JF - Vibrational Spectroscopy N2 - Absorption cross-sections provide a basis for many gas sensing applications. Therefore, any error in molecular cross-sections caused by varying environmental conditions propagates to spectroscopic applications. Original molecular cross-sections in varying environmental conditions can only be simulated for some molecules, whereas for most multi-atom molecules, one must rely on high-precision measurements at certain environmental configurations. In this study, a deep learning system trained with simulated absorption cross-sections for predicting cross-sections at a different pressure configuration is presented. The system’s capability to transfer to measured, multi-atom cross-sections is demonstrated. Thus, it provides an alternative to (pseudo-) line lists whenever the required information for simulation is unavailable. The predictive performance of the system was evaluated on validation data via simulation, and its transfer learning capabilities were demonstrated on actual measurement chlorine nitrate data. From the comparison between the system and line lists, the system shows slightly worse performance than pseudo-line lists but its predictive quality is still deemed acceptable with less than 5% relative integral change with a highly localized error around the peak center. This opens a promising way for further research to use deep learning to simulate the effect of varying environmental conditions on absorption cross-sections. KW - Spectroscopy KW - Deep learning KW - Simulation KW - Pressure broadening KW - Pseudo-line lists KW - Transfer learning Y1 - 2022 U6 - https://doi.org/10.1016/j.vibspec.2022.103410 SN - 0924-2031 VL - 122 IS - September PB - Elsevier ER - TY - GEN A1 - Hipp, Susanne T1 - Designing steerable antenna arrays using simulation T2 - GeMIC 2020 N2 - Antenna arrays are one possibility to design a steerable antenna. Designing an antenna array is a challenging task, where simulation can help to reduce the design complexity. Simulating a complete array can be computational expensive, therefore designing the array is often broken in several task. The first goal is to design and optimize a single antenna element followed by an optimization of this antenna element while considering the vicinity of further equal elements. A unit cell approach is a feasible and easy way to accomplish this task. This approach already considers parameter such as active element pattern and radiation pattern angles. As soon as the unit cell optimization, emulating an infinite array, is finished, the real array with a finite size is simulated, especially considering edge elements and parameters such as excitation patterns or active and passive elements. Due to the high simulation effort at this stage optimization should be kept to a minimum and high performance computing might be required. Finally, a feeding network and different excitations for various beam patterns can be investigated using combined methods to reduce the simulation effort. KW - Antennengruppe KW - Entwurf KW - Simulation Y1 - 2020 ER - TY - JOUR A1 - Hager, Markus A1 - Seitz, Jochen A1 - Waas, Thomas T1 - Literature Survey on Recent Progress in Inter-Vehicle Communication Simulations JF - Journal of Transportation Technologies N2 - The vehicular ad hoc network (VANET) technology based on the approved IEEE 802.11p standard and the appendant inter-vehicle communication (IVC) has the potential to dramatically change the way transportation systems work. The fundamental idea is to change the individual behavior of each vehicle by exchanging information among traffic participants to realize a cooperative and more efficient ransportation system. Certainly, the evaluation of such systems is a comprehensive and challenging task in a real world test bed, therefore, simulation frameworks are a key tool to analyze IVC. Several models are needed to emulate the real behavior of a VANET in all aspects as much realistically as necessary. The intention of this survey is to provide a comprehensive overview of publications concerning IVC simulations of the year 2013 and to see how IVC simulation has changed since 2009. Based on this analysis, we will answer the following questions: What simulation techniques are applied to IVC? Which aspects of IVS have been evaluated? What has changed within five years of IVC simulations? We also take a closer look at commonly used software tools and discuss their functionality and drawbacks. Finally, we present open questions concerning IVC simulations. KW - Inter-Vehicle Communication KW - Simulation KW - Survey Y1 - 2015 UR - https://file.scirp.org/pdf/JTTs_2015071315165413.pdf U6 - https://doi.org/10.4236/jtts.2015.53015 VL - Vol. 5 IS - 3 SP - 159 EP - 168 ER - TY - JOUR A1 - Melzner, Maximilian A1 - Engelhardt, Lucas A1 - Simon, Ulrich A1 - Dendorfer, Sebastian T1 - Electromyography-Based Validation of a Musculoskeletal Hand Model JF - Journal of Biomechanical Engineering N2 - Regarding the prevention of injuries and rehabilitation of the human hand, musculoskeletal simulations using an inverse dynamics approach allow for insights of the muscle recruitment and thus acting forces on the hand. Currently, several hand models from various research groups are in use, which are mainly validated by the comparison of numerical and anatomical moment arms. In contrast to this validation and model-building technique by cadaver studies, the aim of this study is to further validate a recently published hand model [1] by analyzing numerically calculated muscle activities in comparison to experimentally measured electromyographical signals of the muscles. Therefore, the electromyographical signals of 10 hand muscles of five test subjects performing seven different hand movements were measured. The kinematics of these tasks were used as input for the hand model, and the numerical muscle activities were computed. To analyze the relationship between simulated and measured activities, the time difference of the muscle on- and off-set points was calculated, which resulted in a mean on- and off-set time difference of 0.58 s between the experimental data and the model. The largest differences were detected for movements that mainly addressed the wrist. One major issue comparing simulated and measured muscle activities of the hand is cross-talk. Nevertheless, the results show that the hand model fits the experiment quite accurately despite some limitations and is a further step toward patient-specific modeling of the upper extremity. KW - Elektromyographie KW - Biomechanik KW - Simulation KW - Electromyography KW - Muscle KW - Musculoskeletal system KW - Signals KW - Simulation Y1 - 2021 U6 - https://doi.org/10.1115/1.4052115 VL - 144 IS - 2 PB - American Society of Mechanical Engineers, ASME ER - TY - JOUR A1 - Melzner, Maximilian A1 - Suess, Franz A1 - Dendorfer, Sebastian T1 - The impact of anatomical uncertainties on the predictions of a musculoskeletal hand model – a sensitivity study JF - Computer Methods in Biomechanics and Biomedical Engineering N2 - Outputs of musculoskeletal models should be considered probabilistic rather than deterministic as they are affected by inaccuracies and estimations associated with the development of the model. One of these uncertainties being critical for modeling arises from the determination of the muscles' line of action and the physiological cross-sectional area. Therefore, the aim of this study was to evaluate the outcome sensitivity of model predictions from a musculoskeletal hand model in comparison to the uncertainty of these input parameters. For this purpose, the kinematics and muscle activities of different hand movements (abduction of the fingers, abduction of the thumb, and flexion of the thumb) were recorded. One thousand simulations were calculated for each movement using the Latin hypercube sampling method with a corresponding variation of the muscle origin/insertion points and the cross-sectional area. Comparing the standard hand to simulations incorporating uncertainties of input parameters shows no major deviations in on- and off-set time point of muscle activities. About 60% of simulations are located within a ± 30% interval around the standard model concerning joint reaction forces. The comparison with the variation of the input data leads to the conclusion that the standard hand model is able to provide not over-scattered outcomes and, therefore, can be considered relatively stable. These results are of practical importance to the personalization of a musculoskeletal model with subject-specific bone geometries and hence changed muscle line of action. KW - Biomechanik KW - Simulation Y1 - 2021 U6 - https://doi.org/10.1080/10255842.2021.1940974 SN - 1476-8259 N1 - Corresponding author: Maximilian Melzner VL - 25 IS - 2 SP - 156 EP - 164 PB - Taylor & Francis ER - TY - JOUR A1 - Kramer, Sharlotte L. B. A1 - Jones, Amanda A1 - Mostafa, Ahmed A1 - Ravaji, Babak A1 - Tancogne-Dejean, Thomas A1 - Roth, Christian C. A1 - Nonn, Aida T1 - The third Sandia fracture challenge: predictions of ductile fracture in additively manufactured metal JF - International Journal of Fracture N2 - The Sandia Fracture Challenges provide a forum for the mechanics community to assess its ability to predict ductile fracture through a blind, round-robin format where mechanicians are challenged to predict the deformation and failure of an arbitrary geometry given experimental calibration data. The Third Challenge (SFC3) required participants to predict fracture in an additively manufactured (AM) 316L stainless steel bar containing through holes and internal cavities that could not have been conventionally machined. The volunteer participants were provided extensive data including tension and notched tensions tests of 316L specimens built on the same build-plate as the Challenge geometry, micro-CT scans of the Challenge specimens and geometric measurements of the feature based on the scans, electron backscatter diffraction (EBSD) information on grain texture, and post-test fractography of the calibration specimens. Surprisingly, the global behavior of the SFC3 geometry specimens had modest variability despite being made of AM metal, with all of the SFC3 geometry specimens failing under the same failure mode. This is attributed to the large stress concentrations from the holes overwhelming the stochastic local influence of the AM voids and surface roughness. The teams were asked to predict a number of quantities of interest in the response based on global and local measures that were compared to experimental data, based partly on Digital Image Correlation (DIC) measurements of surface displacements and strains, including predictions of variability in the resulting fracture response, as the basis for assessment of the predictive capabilities of the modeling and simulation strategies. Twenty-one teams submitted predictions obtained from a variety of methods: the finite element method (FEM) or the mesh-free, peridynamic method; solvers with explicit time integration, implicit time integration, or quasi-statics; fracture methods including element deletion, peridynamics with bond damage, XFEM, damage (stiffness degradation), and adaptive remeshing. These predictions utilized many different material models: plasticity models including J2 plasticity or Hill yield with isotropic hardening, mixed Swift-Voce hardening, kinematic hardening, or custom hardening curves; fracture criteria including GTN model, Hosford-Coulomb, triaxiality-dependent strain, critical fracture energy, damage-based model, critical void volume fraction, and Johnson-Cook model; and damage evolution models including damage accumulation and evolution, crack band model, fracture energy, displacement value threshold, incremental stress triaxiality, Cocks-Ashby void growth, and void nucleation, growth, and coalescence. Teams used various combinations of calibration data from tensile specimens, the notched tensile specimens, and literature data. A detailed comparison of results based of these different methods is presented in this paper to suggest a set of best practices for modeling ductile fracture in situations like the SFC3 AM-material problem. All blind predictions identified the nominal crack path and initiation location correctly. The SFC3 participants generally fared better in their global predictions of deformation and failure than the participants in the previous Challenges, suggesting the relative maturity of the models used and adoption of best practices from previous Challenges. This paper provides detailed analyses of the results, including discussion of the utility of the provided data, challenges of the experimental-numerical comparison, defects in the AM material, and human factors. KW - Fracture KW - Rupture KW - Tearing KW - Deformation KW - Plasticity KW - Metal KW - Alloy KW - Additive manufacturing KW - Simulation KW - Prediction KW - Modeling Y1 - 2019 U6 - https://doi.org/10.1007/s10704-019-00361-1 VL - 218 SP - 5 EP - 61 PB - Springer Nature ER - TY - JOUR A1 - Keim, Vincent A1 - Paredes, Marcelo A1 - Nonn, Aida A1 - Münstermann, Sebastian T1 - FSI-simulation of ductile fracture propagation and arrest in pipelines BT - Comparison with existing data of full-scale burst tests JF - International Journal of Pressure Vessels and Piping N2 - The fracture propagation and arrest control for pipelines transporting rich natural gases and high vapor pressure liquids is based on the Battelle Two-Curve Model (BTCM). Distinct limitations of this model were demonstrated for past and modern steels and gas mixtures. These can be related to the insufficient description of individual physical processes and interactions between the pipe material and transported mixture during the running ductile fracture. In the past, fluid-structure interaction (FSI) models enabled a more sophisticated, coupled analysis of the failure scenario. To quantify their capability of describing the multi-physical processes, the FSI models need to be verified by experimental data from full-scale burst tests (FSBT). Therefore, this paper deals with the simulation of five FSBTs from the literature on API grade X65 pipes with different pipe geometries, mixtures and initial conditions. The FSI is modeled by the coupled Euler-Lagrange (CEL) method. The modified Mohr-Coulomb (MMC) model is implemented in the CEL framework to describe the deformation and ductile fracture in the X65/L450 pipes. 3D Euler equations are used to calculate the mixture decompression with the GERG-2008 equation of state defining the volumetric behavior of a CO2-rich mixture, CH4 and H2. The extended model considers the effect of soil backfill on the pipe deformation and inertia. The numerical predictions agree well with the experimental findings in terms of the crack propagation speed and arrest length underlining the capability of the developed numerical tool. KW - Running ductile fracture KW - Crack arrest KW - Fluid-structure interaction KW - MMC model KW - CO2 decompression KW - Bruchmechanik KW - Fluid-Struktur-Wechselwirkung KW - Pipeline KW - Simulation Y1 - 2020 U6 - https://doi.org/10.1016/j.ijpvp.2020.104067 VL - 182 IS - May PB - Elsevier ER - TY - CHAP A1 - Deubzer, Michael A1 - Hobelsberger, Martin A1 - Mottok, Jürgen A1 - Schiller, Frank A1 - Dumke, Reiner A1 - Siegle, Markus A1 - Margull, Ulrich A1 - Niemetz, Michael A1 - Wirrer, Gerhard T1 - Modeling and Simulation of Embedded Real-Time Multi-Core Systems T2 - Proceedings of the 3rd Embedded Software Engineering Congress, 7. bis 9. Dezember 2010, Sindelfingen KW - Real-Time Systems KW - Multicore KW - Model-Driven Development KW - Architecture Description Language KW - Simulation Y1 - 2010 UR - https://www.unibw.de/technische-informatik/mitarbeiter/professoren/siegle/publikationen/ese2010_muco_modsim.pdf ER - TY - CHAP A1 - Käsbauer, Johannes A1 - Schmailzl, Anton A1 - Prehm, Jens A1 - Loose, Tobias A1 - Hierl, Stefan T1 - Simulation of Quasi-Simultaneous Laser Transmission Welding of Plastics BT - Optimization of Material Parameters in Broad Temperature Range T2 - Procedia CIRP N2 - Thermo-mechanical simulation offers great opportunities to optimize welding processes of plastics. For realistic simulation, the temperature dependent mechanical properties need to be implemented from ambient temperature to temperatures above the flow temperature. Standard test methods are insufficient for characterization in the entire temperature range because close to the flow temperature the material is too soft for tensile tests and too stiff for rheometry. Therefore, an optimization strategy is developed, that determines unknown material parameters by testing in welding simulations. The unknown parameters are iteratively adjusted to minimize the mismatch between computed and measured set-paths. Thus, important process characteristics are calculated realistically, enabling the computer aided assessment of the weld quality. KW - plastics welding KW - simulation KW - material modelling KW - optimization KW - parameterization KW - Kunststoffschweißen KW - Thermomechanische Eigenschaft KW - Simulation Y1 - 2020 U6 - https://doi.org/10.1016/j.procir.2020.09.136 VL - 94 SP - 737 EP - 741 PB - Elsevier ER - TY - JOUR A1 - Weber, Karsten T1 - Simulationen in den Sozialwissenschaften JF - Journal for General Philosophy of Science N2 - Computer simulation—hereafter just called ‘simulation’— more and more is getting an important tool in scientific research and development. Simulations provide powerful means for quite different scientific disciplines, for instance for cosmology as well as for economics, and it seems that they can help to extend the borderline of science. However, from a methodological point of view, besides their benefits one can identify several theoretical problems which can occur in the process of scientific research. Some of these problems shall be discussed and consequences of these problems for the use of simulations shall be outlined. KW - Instrumentalismus KW - Realismus KW - Simulation KW - Theorieprütung Y1 - 2007 U6 - https://doi.org/10.1007/s10838-006-9011-8 VL - 38 IS - 1 SP - 111 EP - 126 ER - TY - JOUR A1 - De Pieri, Enrico A1 - Atzori, Federica A1 - Ferguson, Stephen J. A1 - Dendorfer, Sebastian A1 - Leunig, Michael A1 - Aepli, Martin T1 - Contact force path in total hip arthroplasty: effect of cup medialisation in a whole-body simulation JF - HIP International N2 - Background: Cup medialisation down to the true acetabular floor in total hip arthroplasty with a compensatory femoral offset increase seems to be mechanically advantageous for the abductor muscles due to the relocation of the lever arms (body weight lever arm decreased, abductor lever arm increased). However, limited information is currently available about the effects of this reconstruction type at the head cup interface, compared to an anatomical reconstruction that maintains the natural lever arms. Through a whole-body simulation analysis, we compared medialised versus anatomical reconstruction in THA to analyse the effects on: (1) contact force magnitude at the head cup interface; (2) contact force path in the cup; and (3) abductor activity. Methods: Musculoskeletal simulations were performed to calculate the above-mentioned parameters using inverse dynamics analysis. The differences between the virtually implanted THAs were calculated to compare the medialised versus anatomical reconstruction. Results: Cup medialisation with compensatory femoral offset increase led to: (1) a reduction in contact force magnitude at the head cup interface up to 6.6%; (2) a similar contact force path in the cup in terms of sliding distance and aspect ratio; and (3) a reduction in abductor activity up to 17.2% (gluteus medius). Conclusions: In our opinion, these potential biomechanical gains do not generally justify a fully medialised reconstruction, especially in younger patients that are more likely to undergo revision surgery in their lifetime. Cup medialisation should be performed until sufficient press fit and bony coverage of a properly sized and oriented cup can be achieved. KW - Cup medialisation KW - femoral offset KW - hip contact force KW - total hip anthroplasty KW - total hip replacement KW - Hüftgelenkprothese KW - Kontaktkraft KW - Biomechanische Analyse KW - Simulation Y1 - 2020 U6 - https://doi.org/10.1177/1120700020917321 VL - 31 IS - 5 SP - 624 EP - 631 PB - Sage ER - TY - JOUR A1 - Aurbach, Maximilian A1 - Spicka, Jan A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Evaluation of musculoskeletal modelling parameters of the shoulder complex during humeral abduction above 90° JF - Journal of Biomechanics N2 - Based on electromyographic data and force measurements within the shoulder joint, there is an indication that muscle and resulting joint reaction forces keep increasing over an abduction angle of 90°. In inverse dynamics models, no single parameter could be attributed to simulate this force behaviour accordingly. The aim of this work is to implement kinematic, kinetic and muscle model modifications to an existing model of the shoulder (AnyBody™) and assess their single and combined effects during abduction up to 140° humeral elevation. The kinematics and the EMG activity of 10 test subjects were measured during humeral abduction. Six modifications were implemented in the model: alternative wrapping of the virtual deltoid muscle elements, utilization of a three element Hill model, strength scaling, motion capture driven clavicle elevation/protraction, translation of the GH joint in dependency of the acting forces and an alteration of the scapula/clavicle rhythm. From the six modifications, 16 different combinations were considered. Parameter combinations with the Hill model changed the resultant GH joint reaction force and led to an increase in force during abduction of the humerus above 90°. Under the premise of muscle activities and forces within the GH joint rising after 90° of humeral abduction, we propose that the Hill type muscle model is a crucial parameter for accurately modelling the shoulder. Furthermore, the outcome of this study indicates that the Hill model induces the co-contraction of the muscles of the shoulder without the need of an additional stability criterion for an inverse dynamics approach. KW - Shoulder joint KW - Musculoskeletal modelling KW - EMG KW - Glenohumeral joint reaction force KW - Muscle model KW - Schultergelenk KW - Bewegungsapparat KW - Biomechanik KW - Simulation Y1 - 2020 U6 - https://doi.org/10.1016/j.jbiomech.2020.109817 VL - 106 IS - June PB - Elsevier ER - TY - CHAP A1 - Jungtäubl, Dominik A1 - Schmitz, Paul A1 - Gross, Simon A1 - Dendorfer, Sebastian ED - Badnjevic, Almir T1 - FEA of the transiliacal internal fixator as an osteosynthesis of pelvic ring fractures T2 - CMBEBIH 2017, Proceedings of the International Conference on Medical and Biological Engineering 2017 N2 - Common Schanz screw systems can be used to stabilize pelvic ring fractures. In order to accommodate for different patient’s requirements, implants can be placed in cranio-caudal direction into the os ilium (T1), or into the supraacetabular bone canal, and thus, in dorso-ventral direction (T2). Whereas both techniques are currently used, no data of the biomechanical behavior is available up to this date. The aim of this study is to analyze, whether T2 shows biomechanical advantages with respect to tissue and implant stresses due to the enlarged bone-implant interface. Forces acting on the pelvis were analyzed using motion capture data of a gait cycle obtained by the utilization of a musculoskeletal simulation program. A three dimensional finite element (FE) model of the pelvis with grayscale-based material properties was generated. The muscle and joint reaction forces at toe-off were applied to the FE model and instable pelvis fractures were implemented. The osteosynthesis systems were positioned within the model in order to enable the comparison between the two different surgical techniques. Stresses and displacements were analyzed for bone tissue, fracture zone and implant. T2 lead to approx. 30% larger displacements in the fracture zone. Von-Mises stresses were larger for T2 in the implant (80 MPa vs. 227 MPa), whereas T1 leads to larger stresses in the bone tissue (200 MPa vs. 140 MPa). Both implantation techniques showed a good biomechanical behavior. Differences could be found with respect to tissue strains and deformations in the fracture zone. If bone quality or fracture healing are of concern, T2 or T1 should be used, respectively. However, both techniques seem to be applicable for cases with no special requirements. Further analyses aim to investigate the behavior under cyclic loading. KW - Finite element analysis KW - Musculoskeletal simulation KW - Internal fixator KW - Pelvic ring fracture KW - Beckenbruch KW - Operationstechnik KW - Finite-Elemente-Methode KW - Biomechanik KW - Simulation Y1 - 2017 SN - 978-981-10-4165-5 U6 - https://doi.org/10.1007/978-981-10-4166-2_32 SP - 212 EP - 217 PB - Springer CY - Singapore ER -