@article{64985, abstract = {{Modern industrial development has necessitated a wide range of joining technologies. Self-pierce riveting has become a prevalent technique for sheet metal assembly, especially in automotive applications. Achieving proper joint geometry and adequate load-bearing capacity depends on appropriate tool selection and precise process control. Material properties and condition also play a significant role in process performance. To accommodate the inevitable variations in component characteristics during production, a robust and stable joining process is essential. The study focuses on investigating the influence of preformed joining partners on the joining process and the joint's load capacity. An EN AW-6014 in T4 condition, as well as an HCT590X, are used as materials for this study. For this purpose, an exemplary process chain consisting of the steps of performing, joining, and shear load testing is studied. Each process step is implemented using an FE model to predict the outcome of subsequent steps. For analysis of the influence of pre-strain, an optimisation software is used to plan and execute variations of the process. These variations are used to create a meta-model that can describe the relationships between pre-forming and characteristic parameters of subsequent process steps. The resulting model is validated by comparing simulation and experimental data. Finally, in a novel approach, the robustness of the presented process chain is analyzed in terms of a tolerable performance level for the joining partners.}}, author = {{Ludwig, Jean-Patrick and Tolke, Emil and Schlichter, Malte Christian and Bobbert, Mathias and Meschut, Gerson}}, issn = {{2666-3309}}, journal = {{Journal of Advanced Joining Processes}}, keywords = {{Self-pierce riveting, FE modelling, Plastic pre-deformation, Meta modelling}}, publisher = {{Elsevier BV}}, title = {{{Numerical analysis of the robustness of self-pierce riveting with pre-formed joining partners}}}, doi = {{10.1016/j.jajp.2026.100391}}, volume = {{13}}, year = {{2026}}, } @article{58492, abstract = {{A coupled finite plasticity ductile damage and failure model is proposed for the finite element simulation of clinch joining, which incorporates stress-state dependency and regularisation by gradient-enhancement of the damage variable. Ductile damage is determined based on a failure indicator governed by a failure surface in stress space. The latter is exemplary chosen as a combination of the Hosford–Coulomb and Cockcroft–Latham–Oh failure criteria for the high and low stress triaxiality range, respectively, to cover the wide stress range encountered in forming. Damage is coupled to elasto-plasticity to capture the damage-induced degradation of the stiffness and flow stress. This affects the material behaviour up to failure, thereby realistically altering the stress state. Consequently, especially for highly ductile materials, where substantial necking and localisation precede material fracture, the failure prediction is enhanced. The resulting stress softening is regularised by gradient-enhancement to obtain mesh-objective results. The analysis of a modified punch test experiment emphasises how the damage-induced softening effect can strongly alter the actual stress state towards failure. Moreover, the impact of successful regularisation is shown, and the applicability of the damage and failure model to clinch joining is proven.}}, author = {{Friedlein, Johannes and Mergheim, Julia and Steinmann, Paul}}, issn = {{0022-5096}}, journal = {{Journal of the Mechanics and Physics of Solids}}, keywords = {{Finite plasticity, Ductile damage, Gradient-enhancement, Stress-state dependency, Failure}}, publisher = {{Elsevier BV}}, title = {{{Modelling of stress-state-dependent ductile damage with gradient-enhancement exemplified for clinch joining}}}, doi = {{10.1016/j.jmps.2025.106026}}, volume = {{196}}, year = {{2025}}, } @inproceedings{62752, abstract = {{In higher education, assessment/examination procedures should be designed to form a coherent learning process that is aligned with the intended learning objectives and planned learning activities. However, in academic teacher education programmes often use assessment formats that are not well aligned with the demands of teachers' actual professional practice. Performance-based assessments can offer an alternative, for example in the form of role-play-based simulations with trained actors representing typical professional activities in environments of reduced complexity. We have developed such a performance-based assessment format for physics teacher education, analogous to the Objective Structured Teaching Examinations (OSTE) approach used in medical education. The OSTE prototype consists of seven short simulative assessments, reflecting four areas of competence (Instruction, Assessment, Pedagogy and Innovation) that form a 90-minute examination course. In order to investigate prospective physics teachers' perceptions of such an assessment format in terms of its suitability as a summative examination procedure, we piloted the OSTE prototype with N = 34 physics student teachers from three German universities using short questionnaires. The results show that participants perceived the OSTE prototype as authentic and relevant, but they also highlight the need for adequate new learning opportunities to prepare for such simulative examinations to be integrated into teacher education programmes.}}, author = {{Vogelsang, Christoph and Grotegut, Lea and Wotschel, Philipp and Janzen, Thomas}}, keywords = {{teacher education, physics, assessment, pre-service teachers}}, location = {{Copenhagen}}, title = {{{Prospective Physics Teachers' Perceptions of an Objective Structured Teaching Examination (OSTE)}}}, year = {{2025}}, } @article{58491, abstract = {{Similar to bulk metal forming, clinch joining is characterised by large plastic deformations and a variety of different 3D stress states, including severe compression. However, inherent to plastic forming is the nucleation and growth of defects, whose detrimental effects on the material behaviour can be described by continuum damage models and eventually lead to material failure. As the damage evolution strongly depends on the stress state, a stress-state-dependent model is utilised to correctly track the accumulation. To formulate and parameterise this model, besides classical experiments, so-called modified punch tests are also integrated herein to enhance the calibration of the failure model by capturing a larger range of stress states and metal-forming-specific loading conditions. Moreover, when highly ductile materials are considered, such as the dual-phase steel HCT590X and the aluminium alloy EN AW-6014 T4 investigated here, strong necking and localisation might occur prior to fracture. This can alter the stress state and affect the actual strain at failure. This influence is captured by coupling plasticity and damage to incorporate the damage-induced softening effect. Its relative importance is shown by conducting inverse parameter identifications to determine damage and failure parameters for both mentioned ductile metals based on up to 12 different experiments.}}, author = {{Friedlein, Johannes and Böhnke, Max and Schlichter, Malte and Bobbert, Mathias and Meschut, Gerson and Mergheim, Julia and Steinmann, Paul}}, issn = {{2504-4494}}, journal = {{Journal of Manufacturing and Materials Processing}}, keywords = {{ductile damage, stress-state dependency, failure, parameter identification, punch test, clinching}}, number = {{4}}, publisher = {{MDPI AG}}, title = {{{Material Parameter Identification for a Stress-State-Dependent Ductile Damage and Failure Model Applied to Clinch Joining}}}, doi = {{10.3390/jmmp8040157}}, volume = {{8}}, year = {{2024}}, } @inproceedings{56983, abstract = {{Detecting the veracity of a statement automatically is a challenge the world is grappling with due to the vast amount of data spread across the web. Verifying a given claim typically entails validating it within the framework of supporting evidence like a retrieved piece of text. Classifying the stance of the text with respect to the claim is called stance classification. Despite advancements in automated fact-checking, most systems still rely on a substantial quantity of labeled training data, which can be costly. In this work, we avoid the costly training or fine-tuning of models by reusing pre-trained large language models together with few-shot in-context learning. Since we do not train any model, our approach ExPrompt is lightweight, demands fewer resources than other stance classification methods and can serve as a modern baseline for future developments. At the same time, our evaluation shows that our approach is able to outperform former state-of-the-art stance classification approaches regarding accuracy by at least 2 percent. Our scripts and data used in this paper are available at https://github.com/dice-group/ExPrompt.}}, author = {{Qudus, Umair and Röder, Michael and Vollmers, Daniel and Ngonga Ngomo, Axel-Cyrille}}, booktitle = {{Proceedings of the 33rd ACM International Conference on Information and Knowledge Management}}, isbn = {{79-8-4007-0436-9/24/10}}, keywords = {{Stance Classification, Few-shot in-context learning, Pre-trained large language models}}, location = {{Boise, ID, USA}}, pages = {{3994 -- 3999}}, publisher = {{ACM}}, title = {{{ExPrompt: Augmenting Prompts Using Examples as Modern Baseline for Stance Classification}}}, doi = {{10.1145/3627673.3679923}}, volume = {{9}}, year = {{2024}}, } @inproceedings{61273, abstract = {{In human-machine explanation interactions, such as tutoring systems or customer support chatbots, it is important for the machine explainer to infer the human user's understanding. Nonverbal signals play an important role for expressing mental states like understanding and confusion in these interactions. However, an individual's expressions may vary depending on other factors. In cases where these factors are unknown, machine learning methods that infer understanding from nonverbal cues become unreliable. Stress for example has been shown to affect human expression, but it is not clear from the current research how stress affects the expression of understanding. To address this gap, we design a paradigm that induces understanding and confusion through game rule explanations. During the explanations, self-perceived understanding and confusion are annotated by the participants. A stress condition is also introduced to enable the investigation of changes in the expression of social signals under stress. We conducted a study to validate the stress induction and participants reported a statistically significant increase in stress during the stress condition compared to the neutral control condition. Additionally, feedback from participants shows that the paradigm is effective in inducing understanding and confusion. This paradigm paves the way for further studies investigating social signals of understanding to improve human-machine explanation interactions for varying contexts.}}, author = {{Paletschek, Jonas}}, booktitle = {{12th International Conference on Affective Computing & Intelligent Interaction}}, keywords = {{Understanding, Nonverbal Social Signals, Stress Induction, Explanation, Machine Learning Bias}}, location = {{Glasgow}}, publisher = {{IEEE}}, title = {{{A Paradigm to Investigate Social Signals of Understanding and Their Susceptibility to Stress}}}, doi = {{10.1109/ACII63134.2024.00040}}, year = {{2024}}, } @inproceedings{62969, author = {{Pollmeier, Pascal and Vogelsang, Christoph and Fechner, Sabine}}, booktitle = {{15th Conference of the European Science Education Research Association (ESERA)}}, keywords = {{Epistemologie, Evidenzen, Daten, Umgang mit Daten, Kompetenzen, Studierende, pre-service teachers}}, location = {{Cappadocia}}, title = {{{Evidence based practice of pre-service teachers}}}, year = {{2023}}, } @article{27186, abstract = {{The presented paper aims to characterize the damage and fracture behavior of HX340LAD Micro-Alloyed steels using small punch test. Variations with respect to punch geometries and cutting clearance are made to describe the damage behavior of the material under different loading conditions. Experimental investigations are conducted to identify the crack initiation in the specimens. Furthermore, the numerical FEM simulations are performed to identify the stress state at crack initiation. It is shown that different stress states from shear to biaxial tension can be achieved by changing the geometries of punch and varying the cutting clearance. Moreover, it is presented how changing the configurations can influence the stress state variables: Triaxiality and lode angle parameter.}}, author = {{Otroshi, Mortaza and Meschut, Gerson}}, issn = {{1350-6307}}, journal = {{Engineering Failure Analysis}}, keywords = {{Ductile damage, stress state, small punch test, triaxiality, lode angle parameter}}, number = {{c}}, publisher = {{Elsevier}}, title = {{{Influence of cutting clearance and punch geometry on the stress state in small punch test }}}, doi = {{10.1016/j.engfailanal.2022.106183}}, volume = {{136}}, year = {{2022}}, } @inproceedings{40046, abstract = {{Theoretical approaches to the transformation towards an inclusive educational system in Germany mostly agree on the involvement of developmental tasks in subject related research (Hinz, 2011). The common understanding of inclusion as a process geared towards equal participation of all children (Booth, 2012) requires a reflexive questioning of established values, attitudes and practices in order to develop inclusive subject related research, teacher training and teaching and learning (Pech & Schomaker, 2013). Among other things, this results in consequences for the design of pre- service teacher training. To a large extent, teacher education is driven by the promotion of central competencies, interests and self-efficacy (Baumert & Kunter, 2011). It aims towards the development and realisation of inclusive interdisciplinary science and social studies (‘Sachunterricht’) in primary education (Moser, 2018). In conjunction with largely acknowledged constructivist approaches to teaching and learning (Möller, 2001), the development of personality, the consideration of basic needs (Deci & Ryan, 1993) and promotion of individual potentials are repeatedly fundamentally represented in subject related and pedagogical considerations (Feuser, 1989; GDSU, 2013). Therefore, the aforementioned constructivist approach is connected to several certain key paradigms for teaching and learning processes (e.g., Vygotskij, 1978; Posner et al., 1982; van de Pol et al., 2010). In this regard, the nature of primary school students’ basic needs have empirically not been sufficiently studied yet. Theoretical frameworks from motivational psychology (Deci & Ryan, 1993) do not explicitly address how individual needs differ and how the diversity of needs can be included in joint-learning, multi-perspective technology education classes. The research project the present paper is part of aims to develop a research-based concept for the professionalisation of pre-service teachers in a seminar course. Therefore, the promotion of the pre- service teachers’ interests and self-efficacy expectations have been assessed in a pre-post research design with a control group visiting another course not related to technology education and inclusion. The present paper describes and discusses first results of the project and will give an outlook on subsequent developmental tasks.}}, author = {{Schröer, Franz and Tenberge, Claudia}}, booktitle = {{PATT39 - PATT on the Edge Technology, Innovation and Education}}, editor = {{Gill, David and Tuff, Jim and Kennedy, Thomas and Pendergast, Shawn and Jamil, Sana}}, keywords = {{Inclusion, basic needs, pre-service teacher training, interest, self-efficacy}}, location = {{St. John’s, Newfoundland and Labrador, Canada}}, pages = {{49--57}}, title = {{{How to enable pre-service teachers to design technological teaching and learning inclusively? – On the nature and consideration of basic needs in teacher training}}}, year = {{2022}}, } @article{25476, abstract = {{This study deals with the damage behavior of metallic materials by the application of different manufacturing processes and using different optical measurement methods to identify the crack initiation in the damage specimen. The study is intended to highlight the importance of considering manufacturing processes and optical measurement methods in a numerical simulation when analyzing the damage behavior of metallic materials. To describe the damage behavior of the material in the process chain simulations, it is important to calibrate the parameters of damage model more accurately. These parameters are determined using experimental investigation of desired damage specimens. In this regard, a selected damage specimen manufactured by different cutting processes is first experimentally and then numerically investigated. It is shown that the manufacturing process and the optical measurement methods influence the stress state analyzed in the numerical simulation.}}, author = {{Otroshi, Mortaza and Meschut, Gerson and Nesakumar, Aathavan}}, journal = {{Journal of Manufacturing Engineering}}, keywords = {{Damage behaviour, Stress triaxiality, Manufacturing process and Optical measurement}}, number = {{3}}, pages = {{70--76}}, title = {{{The influence of manufacturing processes and optical measurement methods on the damage behavior of HX340LAD micro-alloyed steels}}}, doi = {{https://doi.org/10.37255/jme.v16i3pp070-076}}, volume = {{16}}, year = {{2021}}, } @article{20678, author = {{Bielak, Christian Roman and Böhnke, Max and Beck, Robert and Bobbert, Mathias and Meschut, Gerson}}, journal = {{Journal of Advanced Joining Processes. }}, keywords = {{Clinching, process simulation, FEM, pre-straining, sensitivity analysis}}, publisher = {{Elsevier}}, title = {{{Numerical analysis of the robustness of clinching process considering the pre-forming of the parts }}}, doi = {{https://doi.org/10.1016/j.jajp.2020.100038}}, year = {{2020}}, } @article{13155, author = {{Tanaka, Shunji and Tierney, Kevin}}, issn = {{0377-2217}}, journal = {{European Journal of Operational Research}}, keywords = {{OR in maritime industry, Container pre-marshalling, Terminal operations}}, number = {{1}}, pages = {{165 -- 180}}, title = {{{Solving Real-World Sized Container Pre-Marshalling Problems with an Iterative Deepening Branch-and-Bound Algorithm}}}, doi = {{https://doi.org/10.1016/j.ejor.2017.05.046}}, volume = {{264}}, year = {{2018}}, } @inproceedings{9895, abstract = {{Power semiconductor modules are used to control and switch high electrical currents and voltages. Within the power module package wire bonding is used as an interconnection technology. In recent years, aluminum wire has been used preferably, but an ever-growing market of powerful and efficient power modules requires a material with better mechanical and electrical properties. For this reason, a technology change from aluminum to copper is indispensable. However, the copper wire bonding process reacts more sensitive to parameter changes. This makes manufacturing reliable copper bond connections a challenging task. The aim of the BMBF funded project Itsowl-InCuB is the development of self-optimizing techniques to enable the reliable production of copper bond connections under varying conditions. A model of the process is essential to achieve this aim. This model needs to include the dynamic elasto-plastic deformation, the ultrasonic softening effect and the proceeding adhesion between wire and substrate. This paper focusses on the pre-deformation process. In the touchdown phase, the wire is pressed into the V-groove of the tool and a small initial contact area between wire and substrate arise. The local characteristics of the material change abruptly because of the cold forming. Consequently, the pre-deformation has a strong effect on the joining process. In [1], a pre-cleaning effect during the touchdown process of aluminum wires by cracking of oxide layers was presented. These interactions of the process parameters are still largely unknown for copper. In a first step, this paper validates the importance of modeling the pre-deformation by showing its impact on the wire deformation characteristic experimentally. Creating cross-section views of pre-deformed copper wires has shown a low deformation degree compared to aluminum. By using a digital microscope and a scanning confocal microscope an analysis about the contact areas and penetration depths after touchdown has been made. Additionally, it has to be taken into account that the dynamical touchdown force depends on the touchdown speed and the touchdown force set in the bonding machine. In order to measure the overshoot in the force signals, a strain gauge sensor has been used. Subsequently, the affecting factors have been interpreted independently Furthermore, the material properties of copper wire have been investigated with tensile tests and hardness measurements. In a second step, the paper presents finite element models of the touchdown process for source and destination bonds. These models take the measured overshoot in the touchdown forces into account. A multi-linear, isotropic material model has been selected to map the material properties of the copper. A validation of the model with the experimental determined contact areas, normal pressures and penetration depths reveals the high model quality. Thus, the simulation is able to calculate and visualize the three dimensional pre-deformation with an integrated material parameter of the wire if the touchdown parameters of the bonding machine are known. Based on the calculated deformation degrees of wire and substrate, it is probably possible to investigate the effect of the pre-deformation on the pre-cleaning phase in the copper wire bonding.}}, author = {{Unger, Andreas and Sextro, Walter and Althoff, Simon and Eichwald, Paul and Meyer, Tobias and Eacock, Florian and Brökelmann, Michael}}, booktitle = {{Proceedings of the 47th International Symposium on Microelectronics (IMAPS)}}, keywords = {{pre-deformation, copper wire bonding, finite element model}}, pages = {{289--294}}, title = {{{Experimental and Numerical Simulation Study of Pre-Deformed Heavy Copper Wire Wedge Bonds}}}, year = {{2014}}, } @article{9745, abstract = {{In the modeling of piezoelectric Langevin transducers using usual transfer matrix methods, some simplifications have been adopted. This leads to reduction of the model quality. A mixed transfer matrix method is employed in the modeling of Langevin transducers, where the pre-stressed bolt is modeled as a separate four-pole element, which is connected to other elements in parallel. Based on the mixed transfer matrix method, the four (six)-pole element description of the piezoelectric Langevin transducer is built up and the total transfer matrix relation is derived. The resonance frequencies of the transducer are calculated and then measured using the impedance analyzer (HP4192). Experimental result shows that the mixed transfer matrix method has better modeling quality than the usual transfer matrix method for the vibration analysis of piezoelectric Langevin transducers.}}, author = {{Fu, Bo and Li, Chao and Zhang, Jianming and Huang, Zhenwei and Hemsel, Tobias}}, issn = {{1948-5719}}, journal = {{Journal of Korean Physical Society}}, keywords = {{Piezoelectric langevin transducer, Transfer matrix method, Four (six)-pole element description, Pre-stressed bolt}}, number = {{4}}, pages = {{929}}, title = {{{Modeling of Piezoelectric Langevin Transducers by Using Mixed Transfer Matrix Methods}}}, doi = {{10.3938/jkps.57.929}}, volume = {{57}}, year = {{2010}}, } @inproceedings{9568, abstract = {{A simple pre-stress estimate method of Langevin transducers is studied. The measurement setup consists of a capacitor, an impedance converter and a voltmeter. Based on the piezoelectric equation and the basic circuit theory, the mathematical expression between the pre-stress and the voltage across the capacitor is derived. The pre-stress level can then be calculated out of the measurement of the capacitor voltage. In order to evaluate the precision of this method, a force washer is used to measure the pre-stress of the Langevin transducer. The result shows the pre-stress level obtained from this method is 30-40\% higher than the pre-stress level measured by the force washer. This method is simple and can be used to estimate the pre-stress of various Langevin transducers. The precision of this method can be raised if d33 is identified under different pre-stress levels.}}, author = {{Bo, Fu and Ting, Li and Hemsel, Tobias}}, booktitle = {{Piezoelectricity, Acoustic Waves, and Device Applications, 2008. SPAWDA 2008. Symposium on}}, keywords = {{capacitors, impedance convertors, piezoelectric transducers, stress analysis, Langevin transducers, basic circuit theory, capacitor, impedance converter, piezoelectric equation, pre-stress estimating method, voltmeter, Capacitors, Educational institutions, Equations, Force measurement, Impedance measurement, Manufacturing, Mechatronics, Piezoelectric transducers, Voltage, Voltmeters, Langevin transducer, capacitor, piezoelectric element, pre-stress}}, pages = {{324--327}}, title = {{{A simple pre-stress estimating method of langevin transducers}}}, doi = {{10.1109/SPAWDA.2008.4775801}}, year = {{2008}}, }