@article{51197,
  abstract     = {{<jats:p>Clinching is a cost efficient method for joining components in series production. To assure the clinch point’s quality, the force displacement curve during clinching or the bottom thickness are monitored. The most significant geometrical characteristics of the clinch point, neck thickness and undercut, are usually tested destructively by microsectioning. However, micrograph preparation goes ahead with a resetting of elastic deformations and crack-closing after unloading. To generate a comprehensive knowledge of the clinch point’s inner geometry under load, in-situ computed tomography (CT) and acoustic testing (TDA) can be combined. While the TDA is highly sensitive to the inner state of the clinch point, it could detect critical events like crack development during loading. If such events are indicated, the loading process is stopped and a stepped in-situ CT of the following crack and deformation development is performed. In this paper, the concept is applied to the process of clinching itself, providing a detailed three-dimensional insight in the development of the joining zone. A test set-up is used which allows a stepwise clinching of two aluminium sheets EN AW 6014. Furthermore, this set-up is positioned within a CT system. In order to minimize X-ray absorption, a beryllium cylinder is used within the set-up frame and clinching tools are made from Si3N4. The actuator and sensor necessary for the TDA are integrated in the set-up. In regular process steps, the clinching process is interrupted in order to perform a TDA and a CT scan. In order to enhance the visibility of the interface, a thin tin layer is positioned between the sheets prior clinching. It is shown, that the test-set up allows a monitoring of the dynamic behaviour of the specimen during clinching while the CT scans visualize the inner geometry and material flow non-destructively.</jats:p>}},
  author       = {{Köhler, Daniel and Stephan, Richard and Kupfer, Robert and Troschitz, Juliane and Brosius, Alexander and Gude, Maik}},
  issn         = {{1662-9795}},
  journal      = {{Key Engineering Materials}},
  keywords     = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}},
  pages        = {{1489--1497}},
  publisher    = {{Trans Tech Publications, Ltd.}},
  title        = {{{Investigations on Combined &lt;i&gt;In Situ&lt;/i&gt; CT and Acoustic Analysis during Clinching}}},
  doi          = {{10.4028/p-32330d}},
  volume       = {{926}},
  year         = {{2022}},
}

@article{63829,
  abstract     = {{<jats:p>The 3D shear deformation and failure behaviour of a glass fibre reinforced polypropylene in a shear strain rate range of γ˙=2.2×10−4 to 3.4 1s is investigated. An Iosipescu testing setup on a servo-hydraulic high speed testing unit is used to experimentally characterise the in-plane and out-of-plane behaviour utilising three specimen configurations (12-, 13- and 31-direction). The experimental procedure as well as the testing results are presented and discussed. The measured shear stress–shear strain relations indicate a highly nonlinear behaviour and a distinct rate dependency. Two methods are investigated to derive according material characteristics: a classical engineering approach based on moduli and strengths and a data driven approach based on the curve progression. In all cases a Johnson–Cook based formulation is used to describe rate dependency. The analysis methodologies as well as the derived model parameters are described and discussed in detail. It is shown that a phenomenologically enhanced regression can be used to obtain material characteristics for a generalising constitutive model based on the data driven approach.</jats:p>}},
  author       = {{Gerritzen, Johannes and Hornig, Andreas and Gröger, Benjamin and Gude, Maik}},
  issn         = {{2504-477X}},
  journal      = {{Journal of Composites Science}},
  number       = {{10}},
  publisher    = {{MDPI AG}},
  title        = {{{A Data Driven Modelling Approach for the Strain Rate Dependent 3D Shear Deformation and Failure of Thermoplastic Fibre Reinforced Composites: Experimental Characterisation and Deriving Modelling Parameters}}},
  doi          = {{10.3390/jcs6100318}},
  volume       = {{6}},
  year         = {{2022}},
}

@article{36332,
  abstract     = {{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.}},
  author       = {{Neuser, Moritz and Kappe, Fabian and Ostermeier, Jakob and Krüger, Jan Tobias and Bobbert, Mathias and Meschut, Gerson and Schaper, Mirko and Grydin, Olexandr}},
  issn         = {{1438-1656}},
  journal      = {{Advanced Engineering Materials}},
  keywords     = {{Condensed Matter Physics, General Materials Science}},
  number       = {{10}},
  publisher    = {{Wiley}},
  title        = {{{Mechanical Properties and Joinability of AlSi9 Alloy Manufactured by Twin‐Roll Casting}}},
  doi          = {{10.1002/adem.202200874}},
  volume       = {{24}},
  year         = {{2022}},
}

@article{37647,
  abstract     = {{Mechanical joining processes are an essential part of modern lightweight construction. They permit materials of different types to be joined in a way that is suitable for the loads involved. These processes reach their limits, however, as soon as the boundary conditions change. In most cases, these elements are specially adapted to the joining point and cannot be used universally. Changes require cost-intensive adaptation of both the element and the process control, thus making production more complex. This results in high costs due to the increased number of auxiliary joining element variants required and reduces the economic efficiency of mechanical joining. One approach to overcoming this issue is the use of adaptive auxiliary joining elements formed by friction spinning. This article presents the current state of research on pre-hole-free joining with adaptive joining elements. The overall process chain is illustrated, explained and analyzed. Special attention is paid to demonstrating the feasibility of pre-hole-free joining with adaptive joining elements. The chosen mechanical parameters are subsequently listed. Finally, a comprehensive outlook of the future development potential is derived.</jats:p>}},
  author       = {{Wischer, Christian and Homberg, Werner}},
  issn         = {{1662-9795}},
  journal      = {{Key Engineering Materials}},
  keywords     = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}},
  pages        = {{1468--1478}},
  publisher    = {{Trans Tech Publications, Ltd.}},
  title        = {{{Further Development of an Adaptive Joining Technique Based on Friction Spinning to Produce Pre-Hole-Free Joints}}},
  doi          = {{10.4028/p-1n6741}},
  volume       = {{926}},
  year         = {{2022}},
}

@article{30963,
  abstract     = {{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.}},
  author       = {{Ewenz, Lars and Bielak, Christian Roman and Otroshi, Mortaza and Bobbert, Mathias and Meschut, Gerson and Zimmermann, Martina}},
  issn         = {{0944-6524}},
  journal      = {{Production Engineering}},
  keywords     = {{Industrial and Manufacturing Engineering, Mechanical Engineering}},
  number       = {{2-3}},
  pages        = {{305--313}},
  publisher    = {{Springer Science and Business Media LLC}},
  title        = {{{Numerical and experimental identification of fatigue crack initiation sites in clinched joints}}},
  doi          = {{10.1007/s11740-022-01124-z}},
  volume       = {{16}},
  year         = {{2022}},
}

@article{34257,
  abstract     = {{Galvanic corrosion is a destructive process between dissimilar metals. The present paper presents a constructed numerical test case to simulate galvanic corrosion of two dissimilar metals. This test case is used to study the accuracy of different implementations to track the dissolving anode boundary. One technique is to numerically simulate a mesh displacement based on the prescribed displacement at the anode boundary. The second method is to adjust only the boundary elements. Re-meshing after a certain number of time steps is applied to both implementations. They produce similar results for an electrical and electrochemical field problem. This work shows that mesh smoothing does not result in higher accuracy when modeling a moving anode front. Adjusting only the boundary elements is sufficient when frequent re-meshing is used.}},
  author       = {{Harzheim, Sven and Hofmann, Martin and Wallmersperger, Thomas}},
  issn         = {{0001-5970}},
  journal      = {{Acta Mechanica}},
  keywords     = {{Mechanical Engineering, Computational Mechanics}},
  number       = {{11}},
  pages        = {{4427--4439}},
  publisher    = {{Springer Science and Business Media LLC}},
  title        = {{{Comparison of two mesh-moving techniques for finite element simulations of galvanic corrosion}}},
  doi          = {{10.1007/s00707-022-03326-z}},
  volume       = {{233}},
  year         = {{2022}},
}

@article{34069,
  author       = {{Schramm, Britta and Martin, Sven and Steinfelder, Christian and Bielak, Christian Roman and Brosius, Alexander and Meschut, Gerson and Tröster, Thomas and Wallmersperger, Thomas and Mergheim, Julia}},
  issn         = {{2666-3309}},
  journal      = {{Journal of Advanced Joining Processes}},
  keywords     = {{Mechanical Engineering, Mechanics of Materials, Engineering (miscellaneous), Chemical Engineering (miscellaneous)}},
  publisher    = {{Elsevier BV}},
  title        = {{{A Review on the Modeling of the Clinching Process Chain - Part I: Design Phase}}},
  doi          = {{10.1016/j.jajp.2022.100133}},
  volume       = {{6}},
  year         = {{2022}},
}

@article{34068,
  author       = {{Schramm, Britta and Friedlein, Johannes and Gröger, Benjamin and Bielak, Christian Roman and Bobbert, Mathias and Gude, Maik and Meschut, Gerson and Wallmersperger, Thomas and Mergheim, Julia}},
  issn         = {{2666-3309}},
  journal      = {{Journal of Advanced Joining Processes}},
  keywords     = {{Mechanical Engineering, Mechanics of Materials, Engineering (miscellaneous), Chemical Engineering (miscellaneous)}},
  publisher    = {{Elsevier BV}},
  title        = {{{A Review on the Modeling of the Clinching Process Chain - Part II: Joining Process}}},
  doi          = {{10.1016/j.jajp.2022.100134}},
  year         = {{2022}},
}

@article{34070,
  author       = {{Schramm, Britta and Harzheim, Sven and Weiß, Deborah and Joy, Tintu David and Hofmann, Martin and Mergheim, Julia and Wallmersperger, Thomas}},
  issn         = {{2666-3309}},
  journal      = {{Journal of Advanced Joining Processes}},
  keywords     = {{Mechanical Engineering, Mechanics of Materials, Engineering (miscellaneous), Chemical Engineering (miscellaneous)}},
  publisher    = {{Elsevier BV}},
  title        = {{{A Review on the Modeling of the Clinching Process Chain - Part III: Operational Phase}}},
  doi          = {{10.1016/j.jajp.2022.100135}},
  year         = {{2022}},
}

@article{31238,
  author       = {{Kupfer, Robert and Köhler, Daniel and Römisch, David and Wituschek, Simon and Ewenz, Lars and Kalich, Jan and Weiß, Deborah and Sadeghian, Behdad and Busch, Matthias and Krüger, Jan Tobias and Neuser, Moritz and Grydin, Olexandr and Böhnke, Max and Bielak, Christian-Roman and Troschitz, Juliane}},
  issn         = {{2666-3309}},
  journal      = {{Journal of Advanced Joining Processes}},
  keywords     = {{Mechanical Engineering, Mechanics of Materials, Engineering (miscellaneous), Chemical Engineering (miscellaneous)}},
  publisher    = {{Elsevier BV}},
  title        = {{{Clinching of Aluminum Materials – Methods for the Continuous Characterization of Process, Microstructure and Properties}}},
  doi          = {{10.1016/j.jajp.2022.100108}},
  year         = {{2022}},
}

@inbook{29771,
  author       = {{Grydin, Olexandr and Mortensen, Dag and Neuser, Moritz and Lindholm, Dag and Fjaer, Hallvard G. and Schaper, Mirko}},
  booktitle    = {{Light Metals 2022}},
  isbn         = {{9783030925284}},
  issn         = {{2367-1181}},
  publisher    = {{Springer International Publishing}},
  title        = {{{Numerical and Experimental Investigation of Heat Transfer in the Solidification-Deformation Zone During Twin-Roll Casting of Aluminum Strips}}},
  doi          = {{10.1007/978-3-030-92529-1_96}},
  year         = {{2022}},
}

@article{30647,
  abstract     = {{The increasing economic and ecological demands on the mobility sector require efforts to reduce resource consumption in both the production and utilization phases. The use of lightweight construction technologies can save material and increase energy efficiency during operation. Multi-material systems consisting of different materials and geometries are used to achieve weight reduction. Since conventional joining processes reach their limits in the connection of these components, new methods and technologies are necessary in order to be able to react versatilely to varying process and disturbance variables. For fundamental investigations of new possibilities in joining technology, numerical investigations are helpful to identify process parameters. To generate valid results, robust and efficient material models are developed which are adapted to the requirements of versatile joining technologies, for instance to the high plastic strains associated with self-piercing riveting. To describe the inherent strain-induced plastic orthotropy of sheet metal an anisotropic Hill-plasticity model is formulated. Tensile tests for different sheet orientations are conducted both experimentally and numerically to adjust the anisotropic material parameters by inverse parameter identification for aluminium EN AW-6014 and steel HCT590X. Then, the layer compression test is used to validate the model and the previously identified parameters.}},
  author       = {{Friedlein, J. and Wituschek, S. and Lechner, M. and Mergheim, J. and Steinmann, P.}},
  journal      = {{IOP Conference Series: Materials Science and Engineering}},
  pages        = {{012004}},
  title        = {{{Inverse parameter identification of an anisotropic plasticity model for sheet metal}}},
  doi          = {{10.1088/1757-899X/1157/1/012004}},
  volume       = {{1157}},
  year         = {{2021}},
}

@article{30645,
  abstract     = {{As a new and innovative processing method for fabrication for fiber-reinforced thermoplastic composites (CFRTs), the feasibility of ultrasonic welding technology was proven in several studies. This method offers potential for the direct manufacturing of CFRT–metal structures via embedded pin structures. Despite the previous studies, a deeper understanding of the process of energy input and whether fibers work as energy directors and consequently can, in combination with chosen processing parameters, influence the consolidation quality of the CFRTs, is still unknown. Consequently, the aim of this work is to establish a deeper process understanding of the ultrasonic direct impregnation of fiber-reinforced thermoplastics with an emphasis on the fiber’s function as energy directors. Based on the generated insights, a better assessment of the feasibility of direct, hybrid part manufacturing is possible. The produced samples were primarily evaluated by optical and mechanical test methods. It is demonstrated that with higher welding time and amplitude, a better consolidation quality can be achieved and that independent of the process parameters chosen in this study, no significant fiber breakage occurs. This is interpreted as a sign of a gentle impregnation process. Furthermore, based on the examination of single roving and 5-layer set-ups, it is shown that the glass fibers function as energy directors and can influence the transformation of sonic energy into thermal energy. In comparison to industrially available CFRT material, the mechanical properties are weaker, but materials and processes offer potential for significant improvement. Based on these findings, proposals for a direct impregnation and joining process are made.}},
  author       = {{Popp, J. and Wolf, M. and Mattner, T. and Drummer, D.}},
  journal      = {{Journal of Composites Science}},
  pages        = {{239}},
  title        = {{{Energy direction in ultrasonic impregnation of continuous fiber-reinforced thermoplastics}}},
  doi          = {{10.3390/jcs5090239}},
  volume       = {{5}},
  year         = {{2021}},
}

@article{30643,
  abstract     = {{The multi-material design and the adaptability of a modern process chain require joining connections with specifically adjustable mechanical, thermal, chemical, or electrical properties. Previous considerations primarily focused on the mechanical properties. The multitude of possible combinations of requirements, materials, and component- and joining-geometry makes an empirical determination of these joining properties for the clinching process impossible. Based on the established and empirical procedure, there is currently no model that takes into account all questions of joinability—i.e., the materials (suitability for joining), design (security of joining), and production (joining possibility)—that allows a calculation of the properties that can be achieved. It is therefore necessary to describe the physical properties of the joint as a function of the three binding mechanisms—form closure, force closure, and material closure—in relation to the application. This approach illustrates the relationships along the causal chain “joint requirement-binding mechanism-joining parameters” and improves the adaptability of the mechanical joining technology. Geometrical properties of clinch connections of the combination of aluminum and steel are compared in a metallographic cross-section. The mechanical stress state of the rotationally symmetrical clinch points is qualified with a torsion test and by measuring the electrical resistance in the base material, in the clinch joint, and during the production cycle (after clinching, before precipitation hardening and after precipitation hardening).}},
  author       = {{Kalich, J. and Füssel, U.}},
  journal      = {{Journal of Manufacturing and Materials Processing}},
  pages        = {{105}},
  title        = {{{Influence of the production process on the binding mechanism of clinched aluminum steel mixed compounds}}},
  doi          = {{10.3390/jmmp5040105}},
  volume       = {{5}},
  year         = {{2021}},
}

@article{30644,
  abstract     = {{Computational homogenization is a powerful tool allowing to obtain homogenized properties of materials on the macroscale from simulations of the underlying microstructure. The response of the microstructure is, however, strongly affected by variations in the microstructure geometry. In particular, we consider heterogeneous materials with randomly distributed non-overlapping inclusions, which radii are also random. In this work we extend the earlier proposed non-deterministic computational homogenization framework to plastic materials, thereby increasing the model versatility and overall realism. We apply novel soft periodic boundary conditions and estimate their effect in case of non-periodic material microstructures. We study macroscopic plasticity signatures like the macroscopic von-Mises stress and make useful conclusions for further constitutive modeling. Simulations demonstrate the effect of the novel boundary conditions, which significantly differ from the standard periodic boundary conditions, and the large influence of parameter variations and hence the importance of the stochastic modeling.}},
  author       = {{Pivovarov, D. and Mergheim, J. and Willner, K. and Steinmann, P.}},
  journal      = {{Computational Mechanics}},
  title        = {{{Stochastic local FEM for computational homogenization of heterogeneous materials exhibiting large plastic deformations}}},
  doi          = {{10.1007/s00466-021-02099-x}},
  year         = {{2021}},
}

@article{30642,
  abstract     = {{Sheet metal forming as well as mechanical joining demand increasingly accurate and efficient material modelling to capture large deformations, the inherent sheet orthotropy and even process-induced damage, which is expected to be influential. To account for large strains the additive logarithmic strain space is utilised that enables a straightforward incorporation of plastic anisotropy, herein modelled by a Hill48 yield function. A gradient-enhancement is used to equip the ductile damage model with an internal length scale curing the damage-induced localisation. An affine combination of the local and non-local softening variable is derived enabling a more efficient single surface formulation for the regularised plasticity-damage material model.}},
  author       = {{Friedlein, J. and Mergheim, J. and Steinmann, P.}},
  journal      = {{PAMM}},
  title        = {{{Anisotropic plasticity‐damage material model for sheet metal — Regularised single surface formulation}}},
  doi          = {{10.1002/pamm.202100068}},
  volume       = {{21}},
  year         = {{2021}},
}

@inproceedings{20807,
  author       = {{Bielak, Christian Roman and Böhnke, Max and Bobbert, Mathias and Meschut, Gerson}},
  location     = {{Lüttich}},
  title        = {{{Further development of a numerical method for analyzing the load capacity of clinched joints in versatile process chains}}},
  doi          = {{10.25518/esaform21.4298}},
  year         = {{2021}},
}

@article{30650,
  abstract     = {{Due to increasingly strict emission targets and regulatory requirements, especially for companies in the transport industry, the demand for multi-material-systems is continuously rising in order to lower energy consumption. In this context, mechanical joining processes offer an environmentally friendly and flexible alternative to established joining methods, especially in the field of lightweight design. For example, cold-formed cylindrical pin structures show high potentials in joining multi-material-systems without auxiliary elements. The pin structures are joined either by pressing them directly into the joining partner or by caulking with a pre-punched part. However, to evaluate the strength of the joint and to ensure the joining reliability for versatile processes, such as changing joining partners or batch variations, engineering designers currently have only limited design principles available compared to thermal joining processes. Consequently, the design of an optimal pin joint requires cost- and time-intensive experimental investigations and adjustments to design or process parameters. As a solution, data-driven methods offer procedures for structuring data and identifying dependencies between varying process parameters and resulting pin structure characteristics. Motivated by this, the paper presents an approach for the data-driven analysis of cold-formed pin structures and offers a deeper understanding of how versatile processes affect the pin characteristics. Therefore, the application of an intelligent design of experiment in combination with several machine learning methods enable the setup of a best-fitting meta-model. Resulting, the determination of a mathematical model provides the opportunity to accurately estimate the pin height considering only relevant geometrical and process parameters with a prediction quality of 95 %.}},
  author       = {{Römisch, D. and Zirngibl, C. and Schleich, B. and Wartzack, S. and Merklein, M.}},
  journal      = {{IOP Conference Series: Materials Science and Engineering}},
  pages        = {{012077}},
  title        = {{{Data-driven analysis of cold-formed pin structure characteristics in the context of versatile joining processes}}},
  doi          = {{10.1088/1757-899X/1157/1/012077}},
  volume       = {{1157}},
  year         = {{2021}},
}

@article{30648,
  abstract     = {{In clinching, the combinations of requirements, materials, component dimensions and tools influence the resulting joint geometry and the resulting bonding mechanisms. These in turn affect the property profile of the joint. For example, it is possible to use different tools to flexibly adapt clinching points to the respective required load regime. Clinching points dimensioned in this way can be geometrically similar, but have different mechanical stress states, which leads to different properties in terms of load-bearing behavior. Within the scope of this work, the clinching process with different tools in optimal and compromise design and its effect on the force and form-closure component, is investigated in a torsion test of the clinched connection. Clinched steel sheets with two thicknesses and joining directions are analyzed. Virtual experiments are carried out using finite element analyses (FEA) of the joining process and are followed by a springback simulation. Subsequently, the surface pressure between the two joining partners in the clinching points is calculated on the basis of the results from the FEA and the transmittable moment of the connection, as an indicator for the force-closure component, is determined. Finally, the experimental and simulated data are compared and discussed.}},
  author       = {{Steinfelder, C. and Kalich, J. and Brosius, A. and Füssel, U.}},
  journal      = {{IOP Conference Series: Materials Science and Engineering}},
  pages        = {{012003}},
  title        = {{{Numerical and experimental investigation of the transmission moment of clinching points}}},
  doi          = {{10.1088/1757-899x/1157/1/012003}},
  volume       = {{1157}},
  year         = {{2021}},
}

@article{30653,
  abstract     = {{Continuous Fiber Reinforced Thermoplastic (CFRT) hybrid parts offer interesting possibilities for lightweight application, which can exceed the capabilities of mono material metal or CFRT parts. In this case, the joining technology oftentimes is the limiting factor. This study investigates a joining operation with metal pin structures which are additively manufactured via powder bed fusion featuring different diameters and tip geometries, which are inserted into the locally infrared heated CFRT part. The resulting fiber rearrangement is assessed using transmitted light microscopy, confocal laser scanning microscopy as well as micro-computer-tomography. It could be shown that for all assessed pin variants a similar distinct fiber displacement can be seen and that the pin diameter has a significant effect on the resulting fiber orientation with smaller pin diameters being advantageous because of gentle fiber displacement and reduced undulation. The tip geometry has only minor effect on the fiber orientation. Especially in the X/Y plane no systematic influence of the tip geometry on the fiber displacement could be observed. Based on the gained insights a three-stage model of the fiber orientation processes is proposed.}},
  author       = {{Popp, J. and Kleffel, T. and Römisch, D. and Papke, T. and Merklein, M. and Drummer, D.}},
  journal      = {{Applied Composite Materials}},
  pages        = {{951–972}},
  title        = {{{Fiber Orientation Mechanism of Continuous Fiber Reinforced Thermoplastics Hybrid Parts Joined with Metallic Pins}}},
  doi          = {{10.1007/s10443-021-09892-0}},
  volume       = {{28}},
  year         = {{2021}},
}