@article{15945, author = {{Tinkloh, Steffen Rainer and Wu, Tao and Tröster, Thomas and Niendorf, Thomas}}, issn = {{0263-8223}}, journal = {{Composite Structures}}, title = {{{A micromechanical-based finite element simulation of process-induced residual stresses in metal-CFRP-hybrid structures}}}, doi = {{10.1016/j.compstruct.2020.111926}}, volume = {{238}}, year = {{2020}}, } @inproceedings{23409, author = {{Bertling, René and Hack, Mathias and Ausner, Ilja and Kenig, Eugeny}}, title = {{{CFD Simulation of Film and Rivulet Flows on Microstructured Surfaces}}}, year = {{2020}}, } @article{44996, author = {{Brehm, Martin and Thomas, M. and Gehrke, S. and Kirchner, B.}}, journal = {{J. Chem. Phys.}}, pages = {{164105}}, title = {{{TRAVIS – A Free Analyzer for Trajectories from Molecular Simulation}}}, doi = {{10.1063/5.0005078}}, volume = {{152 (16)}}, year = {{2020}}, } @article{45126, abstract = {{Abstract Purpose It has been reported that there is no correlation between anterior tibia translation (ATT) in passive and dynamic situations. Passive ATT (ATTp) may be different to dynamic ATT (ATTd) due to muscle activation patterns. This study aimed to investigate whether muscle activation during jumping can control ATT in healthy participants. Methods ATTp of twenty-one healthy participants was measured using a KT-1000 arthrometer. All participants performed single leg hops for distance during which ATTd, knee flexion angles and knee flexion moments were measured using a 3D motion capture system. During both tests, sEMG signals were recorded. Results A negative correlation was found between ATTp and the maximal ATTd (r = − 0.47, p = 0.028). An N-Way ANOVA showed that larger semitendinosus activity was seen when ATTd was larger, while less biceps femoris activity and rectus femoris activity were seen. Moreover, larger knee extension moment, knee flexion angle and ground reaction force in the anterior-posterior direction were seen when ATTd was larger. Conclusion Participants with more ATTp showed smaller ATTd during jump landing. Muscle activation did not contribute to reduce ATTd during impact of a jump-landing at the observed knee angles. However, subjects with large ATTp landed with less knee flexion and consequently showed less ATTd. The results of this study give information on how healthy people control knee laxity during jump-landing. Level of evidence III }}, author = {{Keizer, Michèle N. J. and Hijmans, Juha M. and Gokeler, Alli and Benjaminse, Anne and Otten, Egbert}}, issn = {{2197-1153}}, journal = {{Journal of Experimental Orthopaedics}}, keywords = {{Orthopedics and Sports Medicine}}, number = {{1}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Healthy subjects with lax knees use less knee flexion rather than muscle control to limit anterior tibia translation during landing}}}, doi = {{10.1186/s40634-020-00246-6}}, volume = {{7}}, year = {{2020}}, } @book{45662, author = {{Lutz, Katharina and Offergeld, Jana and Freymuth, Nina and Arp, Anna Liza}}, title = {{{Gemeinsam Forschung gestalten. Handreichung zu partizipativer Forschung}}}, year = {{2020}}, } @article{34670, author = {{Black, Tobias}}, issn = {{0218-2025}}, journal = {{Mathematical Models and Methods in Applied Sciences}}, keywords = {{Applied Mathematics, Modeling and Simulation}}, number = {{06}}, pages = {{1075--1117}}, publisher = {{World Scientific Pub Co Pte Lt}}, title = {{{Global generalized solutions to a forager–exploiter model with superlinear degradation and their eventual regularity properties}}}, doi = {{10.1142/s0218202520400072}}, volume = {{30}}, year = {{2020}}, } @inproceedings{17355, abstract = {{Ultrasonic wire bonding is a process to form electrical connections in electronics well established industry. Typically, a clamping tool is pressed on the wire and forced to vibrate at relative high frequency 40 to 100 kHz. The ultrasonic vibration is transmitted through the wire into the interface between wire and substrate. Due to frictional processes, contamination like oxide layers are removed from the contact zone, the surface roughness is reduced, and with increasing bond duration an metallic connection of wire and substrate is established. It is known that the amount of ultrasonic energy over time directly influences the strength and reliability of the bond connection, but the determination of optimum bond parameters is still a challenging experimental task. For this, in the past different model approaches have been presented, to calculate the bond quality by simulation. Measuring the friction between wire and substrate to validate these models is a challenging task at ultrasonic bonding frequency. Therefore a versatile test rig for bonding experiments at frequencies lower than 1 kHz is setup to get detailed insight into the different phases of the connection process. It includes a piezoelectric force sensor for the measurement of the three-dimensional process forces, an electrodynamic shaker for the vibration excitation and a conventional tension-compression testing machine to apply the bond normal force. Using this test rig, it is possible to observe the different phases of bond formation in detail, validate and enhance existing models and finally optimize bond parameters for different processes.}}, author = {{Schemmel, Reinhard and Scheidemann, Claus and Hemsel, Tobias and Kirsch, Olaf and Sextro, Walter}}, booktitle = {{CIPS 2020; 11th International Conference on Integrated Power Electronics Systems}}, pages = {{1--6}}, title = {{{Experimental analysis and modelling of bond formation in ultrasonic heavy wire bonding}}}, year = {{2020}}, } @inproceedings{17706, author = {{Schemmel, Reinhard and Krieger, Viktor and Hemsel, Tobias and Sextro, Walter}}, booktitle = {{2020 21st International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE)}}, isbn = {{9781728160498}}, title = {{{Co-simulation of MATLAB and ANSYS for ultrasonic wire bonding process optimization}}}, doi = {{10.1109/eurosime48426.2020.9152679}}, year = {{2020}}, } @inproceedings{56490, author = {{Hieke, Willi and Turhan, Anni-Yasmin}}, booktitle = {{Proceedings of the 6th Workshop on Formal and Cognitive Reasoning co-located with 43rd German Conference on Artificial Intelligence (KI-2020), Online / Bamberg, Germany, September 22, 2020}}, editor = {{Beierle, Christoph and Ragni, Marco and Stolzenburg, Frieder and Thimm, Matthias}}, pages = {{69–82}}, publisher = {{CEUR-WS.org}}, title = {{{Towards Model Transformation in Description Logics - Investigating the Case of Transductions}}}, volume = {{2680}}, year = {{2020}}, } @article{19973, abstract = {{As a result of lightweight design, increased use is being made of high-strength steel and aluminium in car bodies. Self-piercing riveting is an established technique for joining these materials. The dissimilar properties of the two materials have led to a number of different rivet geometries in the past. Each rivet geometry fulfils the requirements of the materials within a limited range. In the present investigation, an improved rivet geometry is developed, which permits the reliable joining of two material combinations that could only be joined by two different rivet geometries up until now. Material combination 1 consists of high-strength steel on both sides, while material combination 2 comprises aluminium on the punch side and high-strength steel on the die side. The material flow and the stress and strain conditions prevailing during the joining process are analysed by means of numerical simulation. The rivet geometry is then improved step-by-step on the basis of this analysis. Finally, the improved rivet geometry is manufactured and the findings of the investigation are verified in experimental joining tests.}}, author = {{Uhe, Benedikt and Kuball, Clara-Maria and Merklein, Marion and Meschut, Gerson}}, journal = {{Production Engineering}}, keywords = {{Self-piercing riveting, Joining technology, Rivet geometry, Multi-material design, High-strength steel, Aluminium}}, pages = {{417--423}}, title = {{{Improvement of a rivet geometry for the self-piercing riveting of high-strength steel and multi-material joints}}}, doi = {{10.1007/s11740-020-00973-w}}, volume = {{14}}, year = {{2020}}, } @article{62777, abstract = {{The simulation of complex engineering components and structures under loads requires the formulation and adequate calibration of appropriate material models. This work introduces an optimisation-based scheme for the calibration of viscoelastic material models that are coupled to gradient-enhanced damage in a finite strain setting. The parameter identification scheme is applied to a self-diagnostic poly(dimethylsiloxane) (PDMS) elastomer, where so-called mechanophore units are incorporated within the polymeric microstructure. The present contribution, however, focuses on the purely mechanical response of the material, combining experiments with homogeneous and inhomogeneous states of deformation. In effect, the results provided lay the groundwork for a future extension of the proposed parameter identification framework, where additional field-data provided by the self-diagnostic capabilities can be incorporated into the optimisation scheme.}}, author = {{Schulte, Robin and Ostwald, Richard and Menzel, Andreas}}, issn = {{1996-1944}}, journal = {{Materials}}, number = {{14}}, publisher = {{MDPI AG}}, title = {{{Gradient-Enhanced Modelling of Damage for Rate-Dependent Material Behaviour—A Parameter Identification Framework}}}, doi = {{10.3390/ma13143156}}, volume = {{13}}, year = {{2020}}, } @article{63329, abstract = {{AbstractRecent experimental work has revealed that interstitial fluid flow can mobilize two types of tumor cell migration mechanisms. One is a chemotactic-driven mechanism where chemokine (chemical component) bounded to the extracellular matrix (ECM) is released and skewed in the flow direction. This leads to higher chemical concentrations downstream which the tumor cells can sense and migrate toward. The other is a mechanism where the flowing fluid imposes a stress on the tumor cells which triggers them to go in the upstream direction. Researchers have suggested that these two migration modes possibly can play a role in metastatic behavior, i.e., the process where tumor cells are able to break loose from the primary tumor and move to nearby lymphatic vessels. In Waldeland and Evje (J Biomech 81:22–35, 2018), a mathematical cell–fluid model was put forward based on a mixture theory formulation. It was demonstrated that the model was able to capture the main characteristics of the two competing migration mechanisms. The objective of the current work is to seek deeper insight into certain qualitative aspects of these competing mechanisms by means of mathematical methods. For that purpose, we propose a simpler version of the cell–fluid model mentioned above but such that the two competing migration mechanisms are retained. An initial cell distribution in a one-dimensional slab is exposed to a constant fluid flow from one end to the other, consistent with the experimental setup. Then, we explore by means of analytical estimates the long-time behavior of the two competing migration mechanisms for two different scenarios: (i) when the initial cell volume fraction is low and (ii) when the initial cell volume fraction is high. In particular, it is demonstrated in a strict mathematical sense that for a sufficiently low initial cell volume fraction, the downstream migration dominates in the sense that the solution converges to a downstream-dominated steady state as time elapses. On the other hand, with a sufficiently high initial cell volume fraction, the upstream migration mechanism is the stronger in the sense that the solution converges to an upstream-dominated steady state. }}, author = {{Evje, Steinar and Winkler, Michael}}, issn = {{0938-8974}}, journal = {{Journal of Nonlinear Science}}, number = {{4}}, pages = {{1809--1847}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Mathematical Analysis of Two Competing Cancer Cell Migration Mechanisms Driven by Interstitial Fluid Flow}}}, doi = {{10.1007/s00332-020-09625-w}}, volume = {{30}}, year = {{2020}}, } @article{19313, abstract = {{The increasingly simulation-driven design process of ultrasonic transducers requires several reliable parameters for the description of the material behaviour. Exact results can only be achieved when a single specimen is used in the identification process, which typically is prone to the problem of low sensitivities to certain material parameters and thus high uncertainties. Therefore, a custom electrode topology for increased sensitivity is proposed for a piezoceramic disc. The thereupon conducted measurements of the electric impedance can be used as a starting point for an inverse approach where an equivalent simulation model is used to identify fitting material parameters. An optimisation strategy based on a preliminary sensitivity analysis is presented that leads to a good agreement between measurement and simulation. Furthermore, the proposed measurement procedure is able to evaluate the quality of the simulation model. Hence, different frequency-dependent damping models are presented and evaluated.}}, author = {{Feldmann, Nadine and Schulze, Veronika and Claes, Leander and Jurgelucks, Benjamin and Walther, Andrea and Henning, Bernd}}, issn = {{2196-7113}}, journal = {{tm - Technisches Messen}}, pages = {{50--55}}, title = {{{Inverse piezoelectric material parameter characterization using a single disc-shaped specimen}}}, doi = {{10.1515/teme-2020-0012}}, year = {{2020}}, } @inproceedings{29880, abstract = {{Although there are numerous design methodologies for the LLC resonant converter, they often do not consider the possibility of input voltage adjustment. In the proposed concept, a modular multi-level converter (MMC) is used to step-down the three-phase medium voltage of 10 kV, and provide up to 1 MW of pure DC power to the load consisting of electrolyzers for hydrogen generation. Therefore, each module is extended by an LLC resonant converter to adapt to the specific electrolyzers DC voltage range of 142...220 V and to provide galvanic isolation. In order to achieve a high efficiency for a wide range of load conditions, the input voltage of the LLC converter is adjusted between 600 V and 770 V while operating at resonance or close to resonance. The parameters of the 11kW LLC resonant converter with an integrated leakage inductance are systematically optimized to maximize the efficiency for all loads while achieving zero-voltage switching. For a fast estimation of eddy current losses, a new method is proposed, which uses a single FEM simulation to fit newly developed loss equations. The calculated average efficiency is 97.8%. The prototype of the LLC converter reaches a peak efficiency of over 98% at resonance at half load which is similar to the precalculated value.}}, author = {{Unruh, Roland and Schafmeister, Frank and Böcker, Joachim}}, booktitle = {{2020 IEEE 21st Workshop on Control and Modeling for Power Electronics (COMPEL)}}, keywords = {{Full-bridge, High voltage power converters, LLC resonant converter, Multilevel converters, ZVS Converters}}, publisher = {{IEEE}}, title = {{{11kW, 70kHz LLC Converter Design with Adaptive Input Voltage for 98% Efficiency in an MMC}}}, doi = {{10.1109/compel49091.2020.9265771}}, year = {{2020}}, } @inproceedings{24026, abstract = {{In this paper we present a new system concept for an optoelectronic wireless phased array system. Like in a conventional phased array system with optical carrier distribution, optical fibers are used to distribute the carrier from the basestation to the wireless frontends. However in contrast to prior concepts, we propose to use an optical IQ return path from the wireless frontends back to the basestation. Furthermore, we reuse the optical carrier signal for the IQ return path which allows to avoid local oscillator lasers in the wireless frontends and reduces the hardware effort significantly. The system concept allows to integrate all components of an optoelectronic wireless frontend in a single chip using silicon photonics technology.}}, author = {{Kruse, Stephan and Kress, Christian and Scheytt, Christoph and Kurz, Heiko G. and Schneider, Thomas}}, booktitle = {{GeMiC 2020 - German Microwave Conference}}, title = {{{Analysis and Simulation of a Wireless Phased Array System with Optical Carrier Distribution and an Optical IQ Return Path}}}, year = {{2020}}, } @article{21420, author = {{Mair, Christina and Scheffler, Wolfram and Senger, Isabell and Sureth-Sloane, Caren}}, journal = {{Steuer und Wirtschaft}}, number = {{4}}, pages = {{317--329}}, title = {{{Auswirkungen der digitalen Flexibilisierung des Fertigungsortes auf die Verteilung der Besteuerungsrechte – Ergebnisse von Modellrechnungen zum 3D-Druck-Verfahren}}}, volume = {{97}}, year = {{2020}}, } @article{34435, abstract = {{Radial shaft sealing rings (RSSR) are important machine elements used in rotating and oil lubricated systems. Their main task is to prevent oil from exiting the system and dirt particles from entering the system. When this function is not fulfilled, a leakage can occur and cause excessive damage after certain operating times, such as gear failure due to insufficient lubrication. This is the reason for the high level of current research interest in seals. The sealing function of RSSR occurs in the contact area between the sealing lip and the shaft. The contact takes place over a very small contact width of approximately 1 μm. These extremely small dimensions and the complex relationships between the functional influencing variables on the radial shaft sealing system make it difficult to simulate wear on the sealing ring. The energetic consideration of the wear process offers the possibility of quantifying influencing variables more easily by their energetic contribution, which can be determined experimentally. Based on experimentally measured total friction moments, and with the help of a semi-analytical (SA) solid contact model based on the half-space theory, this paper presents a modelling approach for the calculation of wear at the sealing ring. The model presented in this work differs from the existing models in two ways. The first particularity is the coupling of SA method with finite element method (FEM) for the resolution of the contact between the sealing lip and the shaft, allowing a fine discretization of the contact zone (by SA method) and the consideration of the structural behavior (by FE method). The SA method compared to the commonly used FEM presents a great saving in computation time. The second particularity is the use of the real data obtained during the wear tests. Most existing simulation models are based purely on contact pressure. This means that through the contact pressure obtained by simulation and a given sliding distance value, a friction energy will be estimated which will be used in a next step using a wear model such as Archad’s to calculate the wear rate. In this publication the value of friction energy was obtained directly on an experimental basis and a more appropriate wear law, such as Fleischer’s, taking into account the friction conditions, was used to estimate the wear rate.}}, author = {{Foko Foko, Flavien and Heimes, Julia and Magyar, Balázs and Sauer, Bernd}}, issn = {{2075-4442}}, journal = {{Lubricants}}, number = {{2}}, title = {{{Friction Energy-Based Wear Simulation for Radial Shaft Sealing Ring}}}, doi = {{10.3390/lubricants8020015}}, volume = {{8}}, year = {{2020}}, } @article{34436, abstract = {{Regarding the increasing demand in seal lifetime and energy efficiency, a detailed microscopic simulation is necessary—as an addition to experimental investigations—to better understand and improve radial shaft seals. For this purpose, typically thermoelastohydrodynamic lubrication (TEHL) simulations are used. The published models range from rather simple elastohydrodynamic lubrication (EHL) models to very sophisticated TEHL models. Only very few models take into account the roughness or microstructure of both contact surfaces, though, since this would require the consideration of transient effects. In this article, a transient TEHL model for the contact of radial shaft seals is presented. Studies of the sealing contact are conducted, and the possibility of investigating shaft microstructuring is shown.}}, author = {{Thielen, Stefan and Magyar, Balázs and Sauer, Bernd}}, issn = {{0742-4787}}, journal = {{Journal of Tribology}}, number = {{5}}, title = {{{Thermoelastohydrodynamic Lubrication Simulation of Radial Shaft Sealing Rings}}}, doi = {{10.1115/1.4045802}}, volume = {{142}}, year = {{2020}}, } @inproceedings{25617, author = {{Schöppner, Volker and Sporkmann, F.}}, booktitle = {{35th International Conference of the Polymer Processing Society (PPS)}}, location = {{Cesme (Türkei)}}, title = {{{Analysis of the Characteristic Flow Areas for Erdmenger-Elements to Predict the Throughput-Pressure Behavior of Co-Rotating Twin Screw Extruders by Using 3D FEM Simulation}}}, year = {{2019}}, } @inproceedings{20152, author = {{Masendorf, Lukas and Wächter, Michael and Esderts, Alfons and Otroshi, Mortaza and Horstmann, Stephan and Meschut, Gerson}}, location = {{Kassel, Germany}}, title = {{{Erstellung eines Simulationsmodells für die Lebensdauerabschätzung halbhohlstanzgenieteter Bauteile unter zyklischer Belastung}}}, year = {{2019}}, }