TY - JOUR AU - Bloh, Thiemo AU - Caruso, Carina ID - 34198 JF - die hochschullehre TI - Ein kritisch-multiperspektivischer Blick auf Forschendes Lernen in der Lehrkräftebildung. Fragen, Erwägungen und Rekonstruktionen. VL - 8 ER - TY - JOUR AU - Bloh, Thiemo ID - 34199 IS - 6 JF - Zeitschrift für Pädagogik TI - Grundlagentheoretische Differenzen in der Lehrkräftekooperationsforschung VL - 68 ER - TY - JOUR AB - AlSi casting alloys combine excellent castability with high strength. Hence, this group of alloys is often used in the automotive sector. The challenge for this application is the brittle character of these alloys which leads to cracks during joint formation when mechanical joining technologies are used. A rise in ductility can be achieved by a considerable increase in the solidification rate which results in grain refinement. High solidification rates can be realized in twin–roll casting (TRC) by water-cooled rolls. Therefore, a hypoeutectic EN AC–AlSi9 (for European Norm - aluminum cast product) is manufactured by the TRC process and analyzed. Subsequently, joining investigations are performed on castings in as-cast and heat-treated condition using the self-piercing riveting process considering the joint formation and the load-bearing capacity. Due to the fine microstructure, the crack initiation can be avoided during joining, while maintaining the joining parameters, especially by specimens in heat treatment conditions. Furthermore, due to the extremely fine microstructure, the load-bearing capacity of the joint can be significantly increased in terms of the maximum load-bearing force and the energy absorbed. AU - Neuser, Moritz AU - Kappe, Fabian AU - Ostermeier, Jakob AU - Krüger, Jan Tobias AU - Bobbert, Mathias AU - Meschut, Gerson AU - Schaper, Mirko AU - Grydin, Olexandr ID - 34207 IS - 10 JF - Advanced Engineering Materials KW - Condensed Matter Physics KW - General Materials Science SN - 1438-1656 TI - Mechanical Properties and Joinability of AlSi9 Alloy Manufactured by Twin‐Roll Casting VL - 24 ER - TY - CONF AU - Bloh, Thiemo ID - 34203 TI - Was bedeutet Post-Digitalität? – Universitäre Lehrpraktiken zwischen situativer Anforderung und habitueller Prägung ER - TY - CONF AU - Bloh, Thiemo ID - 34201 TI - AussteigerInnen – Fluchtbewegungen in der LehrerInnenbiographie ER - TY - CONF AU - Bloh, Thiemo ID - 34202 TI - „Referenzrahmen“ als gewinnbringendes Konstrukt im Kontext Dokumentarischer Evaluationsforschung!? ER - TY - CONF AU - Bloh, Thiemo ID - 34204 TI - The Deconstruction of Professionalism ER - TY - CHAP AB - Nowadays, clinching is a widely used joining technique, where sheets are joined by pure deformation to create an interlock without the need for auxiliary parts. This leads to advantages such as reduced joining time and manufacturing costs. On the other hand, the joint strength solely relies on directed material deformation, which renders an accurate material modelling essential to reliably predict the joint forming. The formation of the joint locally involves large plastic strains and possibly complex non-proportional loading paths, as typical of many metal forming applications. Consequently, a finite plasticity formulation is utilised incorporating a Chaboche–Rousselier kinematic hardening law to capture the Bauschinger effect. Material parameters are identified from tension–compression tests on miniature spec- imens for the dual-phase steel HCT590X. The resulting material model is implemented in LS-Dyna to study the locally diverse loading paths and give a quantitative statement on the importance of kinematic hardening for clinching. It turns out that the Bauschinger effect mainly affects the springback of the sheets and has a smaller effect on the joint forming itself. AU - Friedlein, Johannes AU - Mergheim, Julia AU - Steinmann, Paul ID - 34211 KW - Clinching KW - Material modelling KW - Kinematic hardening KW - Parameter identification KW - Bauschinger effect SN - 2367-1181 T2 - The Minerals, Metals & Materials Series TI - Influence of Kinematic Hardening on Clinch Joining of Dual-Phase Steel HCT590X Sheet Metal ER - TY - JOUR AB - In this paper, a study based on experimental and numerical simulations is performed to analyze fatigue cracks in clinched joints. An experimental investigation is conducted to determine the failure modes of clinched joints under cyclic loading at different load amplitudes with single-lap shear tests. In addition, numerical FEM simulations of clinching process and subsequent shear loading are performed to support the experimental investigations by analyzing the state of stresses at the location of failure. An attempt is made to explain the location of crack initiation in the experiments using evaluation variables such as contact shear stress and maximum principal stress. AU - Ewenz, L. AU - Bielak, Christian Roman AU - Otroshi, Mortaza AU - Bobbert, Mathias AU - Meschut, Gerson AU - Zimmermann, M. ID - 34213 IS - 2-3 JF - Production Engineering KW - Industrial and Manufacturing Engineering KW - Mechanical Engineering SN - 0944-6524 TI - Numerical and experimental identification of fatigue crack initiation sites in clinched joints VL - 16 ER - TY - CHAP AB - Force–displacement measurements and micrograph analyses are commonly used methods to validate numerical models of clinching processes. However, these methods often lead to resetting of elastic deformations and crack- closing after unloading. In contrast, the in situ computed tomography (CT) can provide three-dimensional images of the clinch point under loading conditions. In this paper, the potential of the in situ investigation of a clinching process as validation method is analyzed. For the in situ testing, a tailored test set-up featuring a beryllium cylinder for load-bearing and clinching tools made from ultra-high-strength titanium and Si3N4 are used. In the experiments, the clinching of two aluminum sheets is interrupted at specific process steps in order to perform the CT scans. It is shown that in situ CT visualizes the inner geometry of the joint at high precision and that this method is suitable to validate numerical models. AU - Köhler, Daniel AU - Kupfer, Robert AU - Troschitz, Juliane AU - Gude, Maik ID - 34212 KW - Clinching KW - Non-destructive testing KW - Computed tomography KW - In situ CT SN - 2367-1181 T2 - The Minerals, Metals & Materials Series TI - Clinching in In Situ CT—A Novel Validation Method for Mechanical Joining Processes ER - TY - JOUR AB - Resource-saving and sustainable production is becoming increasingly important regarding social, political and economic aspects, thus making the use of lightweight-construction technologies a current trend. For this reason, multi-material-systems made of high-strength steel and aluminium as well as metal and fibre-reinforced plastics gain in importance. However, different material properties, e.g. stiffness, thermal expansion coefficients or chemical incompatibilities, are challenging for conventional joining technologies. Joining by cold formed pin structures has shown to have high potential for joining multi-material-systems. These pins can be joined either by direct pin pressing into an unperforated joining partner or by caulking, where the pins are inserted through a pre-punched joining partner and the pin head is upset, resulting in a form-fit joint. Usually, cylindrical pins are used for joining. However, non-rotationally symmetrical pin geometries offer the possibility of introducing a predetermined breaking point or reinforcing a connection in the principal force direction. In this work, cylindrical pins as well as non-rotationally symmetrical pin geometries, such as polygonal and oval pin structures, are cold extruded from the sheet metal plane of an HCT590X+Z dual phase steel and joined in the next step with an EN AW-6014 aluminium using direct pin pressing. Since the formation of an undercut has an crucial influence on the joint strength, the investigations will be focused on the resulting joint geometry. In addition, the effect of different pin heights will be examined to analyse the joint formation at different levels of compression of the pin structures. Finally, the joints are evaluated regarding their joint strength in tensile shear tests and cross tension tests. Here the flow resistance of the geometry used as well as the pin height and thus the strain hardening of the pin base during the extrusion of the pins play a decisive role for the shear strength. AU - Römisch, David AU - Kraus, Martin AU - Merklein, Marion ID - 34219 IS - 6 JF - Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications KW - Mechanical Engineering KW - General Materials Science SN - 1464-4207 TI - Investigation of the influence of formed, non-rotationally symmetrical pin geometries and their effect on the joint quality of steel and aluminium sheets by direct pin pressing VL - 236 ER - TY - JOUR AB - In this study, quasi-unidirectional continuous fiber reinforced thermoplastics (CFRTs) are joined with metal sheets via cold formed cylindrical, elliptical and polygonal pin structures which are directly pressed into the CFRT component after local infrared heating. In comparison to already available studies, the unique novelty is the use of non-rotational symmetric pin structures for the CFRT/metal hybrid joining. Thus, a variation in the fiber orientation in the CFRT component as well as a variation in the non-rotational symmetric pins’ orientation in relation to the sample orientation is conducted. The created samples are consequently mechanically tested via single lap shear experiments in a quasi-static state. Finally, the failure behavior of the single lap shear samples is investigated with the help of microscopic images and detailed photographs. In the single lap shear tests, it could be shown that non-rotational symmetric pin structures lead to an increase in maximum testing forces of up to 74% when compared to cylindrical pins. However, when normalized to the pin foot print related joint strength, only one polygonal pin variation showed increased joint strength in comparison to cylindrical pin structures. The investigation of the failure behavior showed two distinct failure modes. The first failure mode was failure of the CFRT component due to an exceedance of the maximum bearing strength of the pin-hole leading to significant damage in the CFRT component. The second failure mode was pin-deflection due to the applied testing load and a subsequent pin extraction from the CFRT component resulting in significantly less visible damage in the CFRT component. Generally, CFRT failure is more likely with a fiber orientation of 0° in relation to the load direction while pin extraction typically occurs with a fiber orientation of 90°. It is assumed that for future investigations, pin structures with an undercutting shape that creates an interlocking joint could counteract the tendency for pin-extraction and consequently lead to increased maximum joint strengths. AU - Popp, Julian AU - Römisch, David AU - Merklein, Marion AU - Drummer, Dietmar ID - 34223 IS - 10 JF - Applied Sciences KW - Fluid Flow and Transfer Processes KW - Computer Science Applications KW - Process Chemistry and Technology KW - General Engineering KW - Instrumentation KW - General Materials Science SN - 2076-3417 TI - Joining of CFRT/Steel Hybrid Parts via Direct Pressing of Cold Formed Non-Rotational Symmetric Pin Structures VL - 12 ER - TY - JOUR AB - Thermoplastic composites (TPCs) are predestined for use in lightweight structures, especially for high-volume applications. In many cases, joining is a key factor for the successful application of TPCs in multi-material systems. Many joining processes for this material group are based on warm forming the joining zone. This results in a change of the local material structure characterised by modified fibre paths, as well as varying fibre contents, which significantly influences the load-bearing behaviour. During the forming process, many different phenomena occur simultaneously at different scales. In this paper, the deformation modes and flow mechanisms of TPCs during forming described in the literature are first analysed. Based on this, three different joining processes are investigated: embedding of inserts, moulding of contour joints, and hotclinching. In order to identify the phenomena occurring in each process and to describe the characteristic resulting material structure in the joining zones, micrographs as well as computed tomography (CT) analyses are performed for both individual process stages and final joining zones. AU - Troschitz, Juliane AU - Gröger, Benjamin AU - Würfel, Veit AU - Kupfer, Robert AU - Gude, Maik ID - 34225 IS - 15 JF - Materials SN - 1996-1944 TI - Joining Processes for Fibre-Reinforced Thermoplastics: Phenomena and Characterisation VL - 15 ER - TY - JOUR AB - Unter dem Begriff der Auflösung wird für gewöhnlich das kleinste messbare Merkmal eines Messsystems verstanden. In der dimensionellen Computertomografie hingegen haben sich in den vergangenen Jahren mehrere Auflösungskonzepte etabliert, die aufgrund der fehlenden Normung zueinander im Kontrast stehen. In diesem Beitrag werden die drei häufigsten Konzepte, die Voxelgröße, die Ortsauflösung und die metrologische Strukturauflösung in Kürze vorgestellt. Anschließend wird eine Abgrenzung zwischen den Konzepten getroffen und ein Integration der bestehenden Konzepte in ein gemeinsames Amplituden-Wellenlängen Diagramm diskutiert. AU - Binder, Felix AU - Hausotte, Tino ID - 34221 IS - s1 JF - tm - Technisches Messen KW - Electrical and Electronic Engineering KW - Instrumentation SN - 2196-7113 TI - Über die Abgrenzung von Auflösungskonzepten in der industriellen Computertomografie VL - 89 ER - TY - JOUR AB - Die Erkennbarkeit von Rissen und geometrischen Qualitätskennwerten von Fügeverbindungen mittels Computertomografie ist von der Interfacestrukturauflösung abhängig, welche mittels geeigneter Prüfkörper untersucht wird. Die Reduktion von Abbildungsartefakten im Bereich von Bauteilzwischenräumen und -oberflächen verbessert deren dimensionelle Erfassbarkeit. AU - Busch, Matthias AU - Butzhammer, Lorenz AU - Hausotte, Tino ID - 34220 IS - s1 JF - tm - Technisches Messen KW - Electrical and Electronic Engineering KW - Instrumentation SN - 2196-7113 TI - Herausforderungen bei computertomografischen Untersuchungen von Fügeverbindungen VL - 89 ER - TY - CONF AU - Marx, Julian AU - Rieskamp, Jonas AU - Mirbabaie, Milad ID - 33519 T2 - Proceedings of the 33rd Australasian Conference on Information Systems TI - ‘Just a Normal Day in the Metaverse’ – Distraction Conflicts of Knowledge Work in Virtual Environments ER - TY - CONF AU - Alshomary, Milad AU - Rieskamp, Jonas AU - Wachsmuth, Henning ID - 32247 T2 - Proceedings of the 9th International Conference on Computational Models of Argument TI - Generating Contrastive Snippets for Argument Search ER - TY - THES AB - Das Ultraschall-Dickdrahtbonden mit Aluminiumdraht ist ein Standardverfahren zur elektrischenKontaktierung von Leistungshalbleitermodulen. Die steigenden Anforderungen an die Effizienzund Zuverlässigkeit der Module haben zu technologischen Weiterentwicklungen geführt und eswerden vermehrt Kupferdrähte mit wesentlich besseren elektrischen und thermischen Eigenschafteneingesetzt. Hieraus resultieren durch höhere Prozesskräfte und Ultraschallleistung neueHerausforderungen bei der Prozessentwicklung; hierfür wird ein Simulationsmodell zur Verbesserungder Prozessentwicklung entwickelt.In Ultraschall-Drahtbondversuchen mit 400 m Aluminium und Kupfer Drähten wurde der Einflussder Prozessparameter auf die Bondqualität untersucht; diese Ergebnisse und zusätzliche Messungender Drahtdeformation und Schwingungen wurden für die Formulierung der Anforderungenund zur Validierung der Ergebnisse des Simulationsmodells genutzt.Es wurde ein Prozessmodell, basierend auf einer Co-Simulation zwischen MATLAB und ANSYS,entwickelt; hierbei wurden die phyiskalischen Phänomene wie die Ultraschall Werkstoffentfestigung,der Verbindungsaufbau und die dynamischen Systemeigenschaften abgebildet.Basierend auf einer Zug-Druck-Prüfmaschine wurde ein Prüfstand zur Identifikation der Modellparameterentwickelt. In zusätzlichen Druckversuchen mit den Bonddrähten mit und ohneUltraschallanregung wurde die Reduktion der Umformkräfte unter Ultraschalleinfluss untersucht.Mit dem entwickelten Prozessmodell wurden die Parameterstudien aus den Ultraschall-Drahtbondversuchensimuliert und direkt mit den experimentellen Ergebnissen verglichen, wobei sich einerelativ gute Übereinstimmung zwischen Simulation und Messung sowohl für Aluminium, als auchfür Kupfer, erzielen ließ. AU - Schemmel, Reinhard ID - 34272 SN - 978-3-8440-8527-3 TI - Enhanced process development by simulation of ultrasonic heavy wire bonding VL - 13 ER - TY - JOUR AU - Gutt, Jana Kim AU - Thommes, Kirsten ID - 34283 IS - 1 JF - Academy of Management Proceedings KW - Microbiology SN - 0065-0668 TI - Speaking of Performance: Evaluating Team Members’ Performance with Open-Ended Audio Comments VL - 2022 ER - TY - CONF AU - Trentinaglia, Roman ID - 34298 T2 - Proceedings of the 25th International Conference on Model Driven Engineering Languages and Systems: Companion Proceedings TI - Deriving model-based safety and security assurance cases from design rationale of countermeasure patterns ER -