@article{30661, abstract = {{As lightweight design gains more and more attention, time and cost-efficient joining methods such as clinching are becoming more popular. A clinch point’s quality is usually determined by ex situ destructive analyses such as microsectioning. However, these methods do not yield the detection of phenomena occurring during loading such as elastic deformations and cracks that close after unloading. Alternatively, in situ computed tomography (in situ CT) can be used to investigate the loading process of clinch points. In this paper, a method for in situ CT analysis of a single-lap shear test with clinched metal sheets is presented at the example of a clinched joint with two 2 mm thick aluminum sheets. Furthermore, the potential of this method to validate numerical simulations is shown. Since the sheets’ surfaces are locally in contact with each other, the interface between both aluminum sheets and therefore the exact contour of the joining partners is difficult to identify in CT analyses. To compensate for this, the application of copper varnish between the sheets is investigated. The best in situ CT results are achieved with both sheets treated. It showed that with this treatment, in situ CT is suitable to properly observe the three-dimensional deformation behavior and to identify the failure modes.}}, author = {{Köhler, D. and Kupfer, R. and Troschitz, J. and Gude, M.}}, journal = {{Materials}}, pages = {{1859}}, title = {{{In Situ Computed Tomography—Analysis of a Single-Lap Shear Test with Clinch Points}}}, doi = {{10.3390/ma14081859}}, volume = {{14}}, year = {{2021}}, } @article{30719, abstract = {{Due to increasing demands regarding ecological and economic specifications in vehicle design, the effort required for production is continuously increasing. One trend is the increased use of multi-material systems, which are characterised by the use of different materials such as high-strength steels or aluminium alloys. In addition to the varying mechanical properties of the components, an increased number of variants accompanied by different geometries is leading to increasing challenges on body construction. For the assembly and connection of the individual components, conventional joining methods reach their limitations. Therefore, new joining methods are necessary, which feature properties of versatility and can adapt to process and disturbance variables. One way of achieving tailored joints is to use a tumbling self-piercing riveting process. For the design of the process route, numerical investigations are necessary for which a characterisation of the friction properties is necessary. This paper therefore investigates the contact and friction conditions that occur in a tumbling self-piercing riveting process. The individual contacts between the process components are identified and based on this, suitable processes for the characterisation of the friction factors - and coefficients are selected and performed.}}, author = {{Wituschek, S. and Lechner, M.}}, journal = {{Key Engineering Materials}}, pages = {{27--34}}, title = {{{Friction Characterisation for a Tumbling Self-Piercing Riveting Process}}}, doi = {{10.4028/www.scientific.net/kem.883.27}}, volume = {{883}}, year = {{2021}}, } @article{30649, abstract = {{Nowadays, the production of modern lightweight structures, like a body in white structure requires a wide variety of mechanical joining processes. To fulfill the various demands, mechanical joining processes and joining elements (JE) are used. Very often, they are adapted to the application, which leads in turn to a numerous of different variants, high costs, and loss of the process chain versatility. To overcome this drawback, an innovative approach is the usage of individually produced and task-adapted JE, the so-called friction spun joint connectors (FSJC). These connectors can be modified in shape as well as in material properties. This flexibility offers high potential for lightweight design but also increases the necessary analytical effort regarding the forming process as well as the manufactured joint's properties. Therefore, a new analysis strategy based on the Finite-Element-Method (FEM) is proposed, which numerically determines the local load bearing capacity within a given joint in order to identify the critical regions for load transfer. The process of joining element manufacturing and the analysis strategy will be described in detail and optimization results of the joints are shown. Numerical results are discussed and possible recommendations for joint manufacturing are derived.}}, author = {{Wischer, Christian and Steinfelder, Christian and Homberg, Werner and Brosius, Alexander}}, journal = {{IOP Conference Series: Materials Science and Engineering}}, pages = {{012007}}, title = {{{Joining with Friction Spun Joint Connectors – Manufacturing and Analysis}}}, doi = {{10.1088/1757-899x/1157/1/012007}}, volume = {{1157}}, year = {{2021}}, } @article{30702, author = {{Wischer, Christian and Homberg, Werner}}, journal = {{Production Engineering}}, title = {{{A contribution on versatile process chains: joining with adaptive joining elements, formed by friction spinning}}}, doi = {{10.1007/s11740-021-01094-8}}, year = {{2021}}, } @article{30698, author = {{Gröger, B. and Köhler, D. and Vorderbrüggen, J. and Troschitz, J. and Kupfer, R. and Meschut, G. and Gude, M.}}, journal = {{Production Engineering}}, title = {{{Computed tomography investigation of the material structure in clinch joints in aluminium fibre-reinforced thermoplastic sheets}}}, doi = {{10.1007/s11740-021-01091-x}}, year = {{2021}}, } @article{30701, author = {{Römisch, D. and Popp, J. and Drummer, D. and Merklein, M.}}, journal = {{Production Engineering}}, title = {{{Joining of CFRT-steel hybrid parts via hole-forming and subsequent pin caulking}}}, doi = {{10.1007/s11740-021-01093-9}}, year = {{2021}}, } @article{30697, author = {{Lafarge, R. and Wolf, A. and Guilleaume, C. and Brosius, A.}}, journal = {{Minerals, Metals and Materials Series}}, pages = {{1461}}, title = {{{A New Non-destructive Testing Method Applied to Clinching}}}, doi = {{10.1007/978-3-030-75381-8_121}}, year = {{2021}}, } @article{30684, abstract = {{Due to stricter emission targets in the mobility sector and the resulting trend towards lightweight construction in order to reduce weight and consequently emissions, multi-material systems that allow a material to be placed in the right quantity and in the right place are becoming increasingly important. One major challenge that is holding back the rapid and widespread use of multi-material systems is the lack of adequate joining processes that are suitable for joining dissimilar materials. Joining processes without auxiliary elements have the advantage of a reduced assembly effort and no additional added weight. Conventional joining processes without auxiliary elements, such as welding, clinching, or the use of adhesives, reach their limits due to different mechanical properties and chemical incompatibilities. A process with potential in the field of joining dissimilar materials is joining without an auxiliary element using pin structures. However, current pin manufacturing processes are mostly time-consuming or can only be integrated barely into existing industrial manufacturing processes due to their specific properties. For this reason, the present work investigates the production of single- and multi-pin structures from high-strength dual-phase steel HCT590X + Z (DP600, t0 = 1.5 mm) by cold extrusion directly out of the sheet metal. These structures are subsequently joined with an aluminium sheet (EN AW-6014-T4, t0 = 1.5 mm) by direct pin pressing. For a quantitative evaluation of the joint quality, tensile shear tests are carried out and the influence of different pin heights, pin number, and pin arrangements, as well as different joining strategies on the joint strength is experimentally evaluated. It is proven that a single pin structure with a diameter of 1.5 mm and an average height of 1.86 mm achieves a maximum tensile shear force of 1025 N. The results reveal that the formation of a form-fit during direct pin pressing is essential for the joint strength. By increasing the number of pins, a linear increase in force could be demonstrated, which is independent of the arrangement of the pin structures.}}, author = {{Römisch, D. and Kraus, M. and Merklein, M.}}, journal = {{Journal of Manufacturing and Materials Processing}}, pages = {{25}}, title = {{{Experimental study on joining by forming of hct590x + z and en-aw 6014 sheets using cold extruded pin structures}}}, doi = {{10.3390/jmmp5010025}}, volume = {{5}}, year = {{2021}}, } @article{30682, abstract = {{Lightweight constructions become more and more important, especially in the mobility sector. In this industry, the increasingly strict regulations regarding the emissions of carbon dioxide can be achieved to a certain extent by reducing the vehicle weight. Thus, multi-material systems are used. Conventional joining techniques reach their limits when joining different materials due to different thermal expansion, unequal stiffness or chemical incompatibilities. This is why additional joining elements or adhesives are used. These must be viewed critically regarding a lightweight and resource-efficient production, since they add weight or complicate the recycling process of these components. Consequently, there is a great and growing need for new versatile joining technologies in order to overcome these challenges and to be able to react to changing process parameters and boundary conditions. Joining without an auxiliary element using pin structures formed directly from the sheet metal plane is one approach to meet these challenges. These pin structures are then joined by direct pressing into the joining partner. This is possible with a variety of material combinations, but is advantageous with regard to continuous fibre-reinforced thermoplastic composites (CFRTP), as the fibres do not have to be cut when joining CFRTP using pin structures. In this paper, the formability of pin structures made of a dual-phase steel DP600 (HCT590X + Z) is investigated. The extruded pin structures are joined by direct pin pressing with an EN AW-6014 to form tensile shear specimens. Different joining strategies are investigated to compare their influence on the joint strength. The results have shown that it is feasible to form suitable pins from a DP600 dual-phase steel to produce reliable connections with an aluminium sheet joined by direct pin pressing. }}, author = {{Römisch, D. and Kraus, M. and Merklein, M.}}, journal = {{Key Engineering Materials}}, pages = {{19--26}}, title = {{{Investigation of Different Joining by Forming Strategies when Connecting Different Metals without Auxiliary Elements}}}, doi = {{10.4028/www.scientific.net/kem.883.19}}, volume = {{883}}, year = {{2021}}, } @article{30718, abstract = {{The growing demands of resource-saving processes and products are leading to increasing importance of lightweight construction for the automotive industry. One approach is multi-material design, which uses high-strength steels and aluminium alloys in the production of vehicle bodies. Therefore, reliable processes for joining components with different mechanical properties and geometries are necessary. As conventional joining processes reach their limits, new versatile processes and methods are required which can adapt to different process conditions and disturbance variables. A widely used joining process to join different materials is self-piercing riveting as a joining by forming method, however it is characterised as inflexible to changing process conditions due to a linear process kinematic and rigid dies. An approach to extend the process limits is the application of a tumbling kinematic for the punch. Thus, an adapted tumbling strategy can be used to influence the joining process and to achieve a controlled material flow in order to manufacture tailored joints. For the fundamental investigation of the process, numerical investigations are necessary. In order to achieve high model quality a precise material modelling is crucial. Therefore, a characterisation of the materials HCT590X+Z and EN AW-6014 as typical materials of multi-material mixes and the rivet material 38B2 is performed. Due to the different stress conditions during tumbling self-piercing riveting suitable characterisation methods are selected and carried out.}}, author = {{Wituschek, S. and Lechner, M.}}, journal = {{ESAFORM 2021}}, title = {{{Material characterisation methods for a tumbling self-piercing riveting process}}}, doi = {{10.25518/esaform21.398}}, year = {{2021}}, } @article{30683, abstract = {{When joining lightweight parts of various materials, clinching is a cost efficient solution. In a production line, the quality of a clinch point is primarily controlled by measurement of dimensions, which are accessible from outside. However, methods such as visual testing and measuring the bottom thickness as well as the outer diameter are not able to deliver any information about the most significant geometrical characteristic of the clinch point, neck thickness and undercut. Furthermore, ex-situ destructive methods such as microsectioning cannot detect elastic deformations and cracks that close after unloading. In order to exceed the current limits, a new non-destructive in-situ testing method for the clinching process is necessary. This work proposes a concept to characterize clinch points in-situ by combining two complementary non-destructive methods, namely, computed tomography (CT) and ultrasonic testing. Firstly, clinch points with different geometrical characteristics are analysed experimentally using ex-situ CT to get a highly spatially resolved 3D-image of the object. In this context, highly X-ray attenuating materials enhancing the visibility of the sheet-sheet interface are investigated. Secondly, the test specimens are modelled using finite element method (FEM) and a transient dynamic analysis (TDA) is conducted to study the effect of the geometrical differences on the deformation energy and to qualify the TDA as a fast in-situ non-destructive method for characterizing clinch points at high temporal resolution. }}, author = {{Köhler, D. and Sadeghian, B. and Kupfer, R. and Troschitz, J. and Gude, M. and Brosius, A.}}, journal = {{Key Engineering Materials}}, pages = {{89--96}}, title = {{{A Method for Characterization of Geometric Deviations in Clinch Points with Computed Tomography and Transient Dynamic Analysis}}}, doi = {{10.4028/www.scientific.net/kem.883.89}}, volume = {{883}}, year = {{2021}}, } @article{30685, abstract = {{Joints are an essential part of modern (lightweight) structures in a broad variety of applications. The reason for this is the rapidly increasing number of different material combinations needing to be joined in application areas like the automotive industry. It is currently common to use numerous auxiliary or standardized elements instead of individually adapted joining elements. This leads to a large number of different joining elements per product and thus to high costs. An innovative approach to overcoming this issue is the design, manufacture and setting of joint-specific joining elements. A good candidate for the manufacture of adapted joining elements of this type is the so-called friction spinning process. The joining elements formed in this way can be specifically adapted to the application in question in terms of both shape and mechanical properties. The part geometry required for the properties of a given joint is formed using a universal forming tool. This makes it possible to form a wide variety of sub geometries for the auxiliary joining part as a function of the prevailing joint condition, using a single forming tool and starting from the same semi-finished bar material. By applying different process strategies for the rotational speed and feed rate during the forming operation, the same part geometry can even be given different local mechanical properties. The following contribution presents the results of ongoing research work and includes the process concept, process properties, tooling and the results of experimental investigations into the joining of two sheet metal parts with help of this new joining process.}}, author = {{Wiens, E. and Wischer, C. and Homberg, W.}}, journal = {{ESAFORM}}, pages = {{4682}}, title = {{{Development of a novel adaptive joining technology employing friction-spun joint connectors (FSJC)}}}, doi = {{10.25518/esaform21.4682}}, year = {{2021}}, } @article{24537, author = {{Neuser, Moritz and Kappe, Fabian and Busch, M and Grydin, Olexandr and Bobbert, Mathias and Schaper, Mirko and Meschut, Gerson and Hausotte, T}}, issn = {{1757-8981}}, journal = {{IOP Conference Series: Materials Science and Engineering}}, title = {{{Joining suitability of cast aluminium for self-piercing riveting}}}, doi = {{10.1088/1757-899x/1157/1/012005}}, year = {{2021}}, } @article{38517, author = {{Popp, Julian and Kleffel, Tobias and Drummer, Dietmar}}, journal = {{Joining Plastics}}, number = {{3-4}}, title = {{{Influence of pin geometry on the joint strength of CFRT-metal hybrid parts with metallic pins}}}, volume = {{15}}, year = {{2021}}, } @inproceedings{34222, abstract = {{Driven by the CO2-emission law by the European government and the increasing costs for raw materials as well as energy, the automotive industry is increasingly using multi-material constructions. This leads to a continuous increase in the use of mechanical joining techniques and especially the self-piercing riveting is of particular importance. The reason for this is the wide range of joining possibilities as well as the high load-bearing capacities of the joints. To be able to react to changing boundary conditions, like material thickness or strength variation of the sheets, research work is crucial with regard to the increase of versatility. In this paper, a numerical study of the influences on the selfpiercing riveting process is presented. For this purpose, the influence of different process parameters such as rivet length and die depth on various quality-relevant characteristics were investigated. With the help of the design of experiment, significant influences were determined and interactions between the individual parameters are shown.}}, author = {{Kappe, Fabian and Bielak, Christian Roman and Sartisson, Vadim and Bobbert, Mathias and Meschut, Gerson}}, booktitle = {{ESAFORM 2021}}, publisher = {{University of Liege}}, title = {{{Influence of rivet length on joint formation on self-piercing riveting process considering further process parameters}}}, doi = {{10.25518/esaform21.4277}}, year = {{2021}}, } @article{22798, abstract = {{The predictive quality of numerical simulations for mechanical joining processes depends on the implemented material model, especially regarding the plasticity of the joining parts. Therefore, experimental material characterization processes are conducted to determine the material properties of sheet metal and generate flow curves. In this regard, there are a number of procedures which are accompanied by varying experimental efforts. This paper presents various methods of determining flow curves for HCT590X as well as EN AW-6014, including varying specimen geometries and diverse hardening laws for extrapolation procedures. The flow curves thus generated are compared considering the variety of plastic strains occurring in mechanical joining processes. The material data generated are implemented in simulation models for the joining technologies, clinching and self-piercing riveting. The influence of the varied methods on the predictive accuracy of the simulation model is analysed. The evaluation of the differing flow curves is achieved by comparing the geometric formation of the joints and the required joining forces of the processes with experimentally investigated joints.}}, author = {{Böhnke, Max and Kappe, Fabian and Bobbert, Mathias and Meschut, Gerson}}, issn = {{2195-8572}}, journal = {{Materials Testing}}, number = {{6}}, pages = {{493--500}}, publisher = {{De Gruyter}}, title = {{{Influence of various procedures for the determination of flow curves on the predictive accuracy of numerical simulations for mechanical joining processes}}}, doi = {{10.1515/mt-2020-0082}}, volume = {{63}}, year = {{2021}}, } @article{34226, abstract = {{The increasing use of multi-material constructions lead to a continuous increase in the use of mechanical joining techniques due to the wide range of joining possibilities as well as the high load-bearing capacities of the joints. Nevertheless, the currently rigid tool systems are not able to react to changing boundary conditions, like changing the material-geometry-combination. Therefore research work is crucial with regard to versatile joining systems. In this paper, a new approach for a versatile self-piercing riveting process considering the joining system as well as the auxiliary joining part is presented.}}, author = {{Kappe, Fabian and Bobbert, Mathias and Meschut, Gerson}}, issn = {{1662-9795}}, journal = {{Key Engineering Materials}}, keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}}, pages = {{3--10}}, publisher = {{Trans Tech Publications, Ltd.}}, title = {{{New Approach for Versatile Self Piercing Riveting: Joining System and Auxiliary Part}}}, doi = {{10.4028/www.scientific.net/kem.883.3}}, volume = {{883}}, year = {{2021}}, } @article{30200, author = {{Wituschek, Simon and Kappe, Fabian and Lechner, Michael}}, journal = {{Production Engineering}}, title = {{{Investigation of the influence of varying tumbling strategies on a tumbling self-piercing riveting process}}}, doi = {{10.1007/s11740-021-01099-3}}, year = {{2021}}, } @article{26082, author = {{Wischer, Christian and Wiens, Eugen and Homberg, Werner}}, issn = {{2666-3309}}, journal = {{Journal of Advanced Joining Processes}}, publisher = {{Elsevier}}, title = {{{Joining with versatile joining elements formed by friction spinning}}}, doi = {{10.1016/j.jajp.2021.100060}}, volume = {{3}}, year = {{2021}}, } @article{51202, abstract = {{When joining lightweight parts of various materials, clinching is a cost efficient solution. In a production line, the quality of a clinch point is primarily controlled by measurement of dimensions, which are accessible from outside. However, methods such as visual testing and measuring the bottom thickness as well as the outer diameter are not able to deliver any information about the most significant geometrical characteristic of the clinch point, neck thickness and undercut. Furthermore, ex-situ destructive methods such as microsectioning cannot detect elastic deformations and cracks that close after unloading. In order to exceed the current limits, a new non-destructive in-situ testing method for the clinching process is necessary. This work proposes a concept to characterize clinch points in-situ by combining two complementary non-destructive methods, namely, computed tomography (CT) and ultrasonic testing. Firstly, clinch points with different geometrical characteristics are analysed experimentally using ex-situ CT to get a highly spatially resolved 3D-image of the object. In this context, highly X-ray attenuating materials enhancing the visibility of the sheet-sheet interface are investigated. Secondly, the test specimens are modelled using finite element method (FEM) and a transient dynamic analysis (TDA) is conducted to study the effect of the geometrical differences on the deformation energy and to qualify the TDA as a fast in-situ non-destructive method for characterizing clinch points at high temporal resolution.}}, author = {{Köhler, Daniel and Sadeghian, Behdad and Kupfer, Robert and Troschitz, Juliane and Gude, Maik and Brosius, Alexander}}, issn = {{1662-9795}}, journal = {{Key Engineering Materials}}, keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}}, pages = {{89--96}}, publisher = {{Trans Tech Publications, Ltd.}}, title = {{{A Method for Characterization of Geometric Deviations in Clinch Points with Computed Tomography and Transient Dynamic Analysis}}}, doi = {{10.4028/www.scientific.net/kem.883.89}}, volume = {{883}}, year = {{2021}}, }