@inproceedings{60439,
  abstract     = {{Abstract. Mechanical joints are traditionally analyzed through destructive micrograph analysis, which may compromise internal geometry and morphology, as evidenced by radial cracks in semi-tubular self-pierce riveting. In contrast, industrial X-ray computed tomography (XCT) offers a non-destructive method for component diagnosis, providing volumetric insights without damaging the sample and enabling dimensional measurement. The DFG-funded Collaborative Research Center TRR 285 is exploring XCT's application in assessing mechanical joinability across various joining processes and materials, particularly in multi-material systems like steel-aluminum joints. XCT faces challenges in accurately capturing multi-material compositions, leading to artifacts that complicate interface detection. This research aims to validate XCT for joint investigations, yielding quantitative characteristics that surpass those from traditional micrograph analysis.}},
  author       = {{Lechner, M. and Borgert, Thomas and Busch, Matthias and Harms, A. and Holtkamp, Pia Katharina and Römisch, D. and Wituschek, Simon and Kappe, Fabian}},
  booktitle    = {{Materials Research Proceedings}},
  issn         = {{2474-395X}},
  publisher    = {{Materials Research Forum LLC}},
  title        = {{{Non-destructive testing in versatile joining processes}}},
  doi          = {{10.21741/9781644903551-12}},
  volume       = {{52}},
  year         = {{2025}},
}

@article{60105,
  abstract     = {{<jats:p> Lightweight design by using low-density and load-adapted materials can reduce the weight of vehicles and the emissions generated during operation. However, the usage of different materials requires innovative joining technologies with increased versatility. In this investigation, the focus is on describing and characterising the failure behaviour of connections manufactured by an innovative thermomechanical joining process with adaptable auxiliary joining elements in single-lap tensile-shear tests. In order to analyse the failure development in detail, the specimens are investigated using in-situ computed tomography (in-situ CT). Here, the tensile-shear test is interrupted at points of interest and CT scans are conducted under load. In addition, the interrupted in-situ testing procedure is validated by comparing the loading behaviour with conventional continuous tensile-shear tests. The results of the in-situ investigations of joints with varying material combinations clearly describe the cause of failure, allowing conclusions towards an improved joint design. </jats:p>}},
  author       = {{Borgert, T and Köhler, D and Wiens, E. and Kupfer, R and Troschitz, J and Homberg, W and Gude, M}},
  issn         = {{1464-4207}},
  journal      = {{Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications}},
  number       = {{12}},
  pages        = {{2299--2306}},
  publisher    = {{SAGE Publications}},
  title        = {{{In-situ computed tomography analysis of the failure mechanisms of thermomechanically manufactured joints with auxiliary joining element}}},
  doi          = {{10.1177/14644207241232233}},
  volume       = {{238}},
  year         = {{2024}},
}

@inproceedings{54650,
  abstract     = {{<jats:p>Abstract. Reducing the weight of vehicles can significantly lower the energy or fuel consumed and thus the emissions during operation. One possibility to assess this is the use of a property adapted multi-material systems containing high strength steel, light metals like aluminium or magnesium and fibre reinforced plastics. While expanding the number of materials used new challenges arise for the production and furthermore the joining technology to manufacture the vehicle made of the multi-material systems. One approach to overcome these challenges is to use innovative and adaptable joining techniques which allows the manufacturing of joints of different material combinations. Extensive research activities on the two stage thermo-mechanical joining process with adaptable joining elements was able to demonstrate the great potentials in terms of joining dissimilar materials with good strength. The previously kinematic and path-based fabrication of auxiliary joining elements is modified in this publication to a form-based approach with a perspective of establishing an efficient process chain using easily and cheaply available rods. Based on the new approach to produce the auxiliary joining elements, it can be demonstrated that a reproducible production of the geometry is possible for the investigated steel as well as aluminium material. </jats:p>}},
  author       = {{Borgert, Thomas and Nordieker, Ansgar Bernhard and Homberg, Werner}},
  booktitle    = {{Materials Research Proceedings}},
  issn         = {{2474-395X}},
  location     = {{Toulouse}},
  publisher    = {{Materials Research Forum LLC}},
  title        = {{{Form-based manufacturing of aluminium and steel auxiliary joining elements as the basis for an efficient joining operation}}},
  doi          = {{10.21741/9781644903131-180}},
  year         = {{2024}},
}

@article{54649,
  author       = {{Borgert, Thomas and Nordieker, Ansgar Bernhard and Wiens, Eugen and Homberg, Werner}},
  issn         = {{2666-3309}},
  journal      = {{Journal of Advanced Joining Processes}},
  publisher    = {{Elsevier BV}},
  title        = {{{Investigations to improve the tool life during thermomechanical and incremental forming of steel auxiliary joining elements}}},
  doi          = {{10.1016/j.jajp.2024.100185}},
  volume       = {{9}},
  year         = {{2024}},
}

@inproceedings{43031,
  abstract     = {{<jats:p>Abstract. Requirements of multi-material construction involve adjustments to standard joining techniques. Especially the growing importance of integral cast components poses additional engineering challenges for the industry. One approach to achieve these goals are adaptable joining elements formed by friction spinning. This approach uses friction-induced heat to form customisable joining elements to join sheets for different boundary conditions, even for brittle cast materials. It is possible to react immediately to adapt to the joining process inline and reduce the amount of different joining elements. As the joining partner serve casting plates of the aluminium casting alloy EN AC–AlSi9, which is processed in the sand casting. Joining hypoeutectic AlSi alloys constitutes a challenge because the brittle character of these cause cracks in the joint during conventional mechanical joining. Furthermore, the friction-induced heat of the novel joining process causes a finer microstructure in the hypoeutectic AlSi9 casting alloy. In particular, the eutectic Si is more fine-grained, resulting in higher joint ductility. This study indicates the joining suitability of a hypoeutectic aluminium casting alloy in combination with adaptive manufactured additional joining elements. Here, various mechanical and microstructural investigations validate the influence of the thermomechanical joining technique. In conclusion, the potential of this joining process is presented regarding the joinability of cast aluminium components. </jats:p>}},
  author       = {{Borgert, Thomas and Neuser, Moritz and Wiens, Eugen and Grydin, Olexandr and Homberg, Werner and Schaper, Mirko}},
  booktitle    = {{Materials Research Proceedings}},
  issn         = {{2474-395X}},
  location     = {{Nürnberg}},
  pages        = {{187--194}},
  publisher    = {{Materials Research Forum LLC}},
  title        = {{{Influence of thermo-mechanical joining process on the microstructure of a hypoeutectic aluminium cast alloy}}},
  doi          = {{10.21741/9781644902417-24}},
  volume       = {{25}},
  year         = {{2023}},
}

@article{47535,
  abstract     = {{<jats:p>Consistent lightweight construction in the area of vehicle manufacturing requires the increased use of multi-material combinations. This, in turn, requires an adaptation of standard joining techniques. In multi-material combinations, the importance of integral cast components, in particular, is increasing and poses additional technical challenges for the industry. One approach to solve these challenges is adaptable joining elements manufactured by a thermomechanical forming process. By applying an incremental and thermomechanical joining process, it is possible to react immediately and adapt the joining process inline to reduce the number of different joining elements. In the investigation described in this publication, cast plates made of the cast aluminium alloy EN AC-AlSi9 serve as joining partners, which are processed by sand casting. The joining process of hypoeutectic AlSi alloys is challenging as their brittle character leads to cracks in the joint during conventional mechanical joining. To solve this, the frictional heat of the novel joining process applied can provide a finer microstructure in the hypoeutectic AlSi9 cast alloy. In detail, its Si is finer-grained, resulting in higher ductility of the joint. This study reveals the thermomechanical joining suitability of a hypoeutectic cast aluminium alloy in combination with adaptively manufactured auxiliary joining elements.</jats:p>}},
  author       = {{Borgert, Thomas and Neuser, Moritz and Hoyer, Kay-Peter and Homberg, Werner and Schaper, Mirko}},
  issn         = {{2504-4494}},
  journal      = {{Journal of Manufacturing and Materials Processing}},
  keywords     = {{Industrial and Manufacturing Engineering, Mechanical Engineering, Mechanics of Materials}},
  number       = {{5}},
  publisher    = {{MDPI AG}},
  title        = {{{Thermomechanical Joining of Hypoeutectic Aluminium Cast Plates}}},
  doi          = {{10.3390/jmmp7050169}},
  volume       = {{7}},
  year         = {{2023}},
}

@article{46483,
  abstract     = {{<jats:p>The demands on joining technology are constantly increasing due to the consistent lightweight construction and the associated increasing material mix. To meet these requirements, the adaptability of the joining processes must be improved to be able to process different material combinations and to react to challenges caused by deviations in the process chain. One example of a highly adaptable process due to the two-step process sequence is thermomechanical joining with Friction Spun Joint Connectors (FSJCs) that can be individually adapted to the joint. In this paper, the potentials of the adaption in the two-stage joining process with aluminium auxiliary joining elements are investigated. To this end, it is first investigated whether a thermomechanical forming process can be used to achieve a uniform and controlled manufacturing regarding the process variable of the temperature as well as the geometry of the FSJC. Based on the successful proof of the high and good repeatability in the FSJC manufacturing, possibilities, and potentials for the targeted influencing of the process and FSJC geometry are shown, based on an extensive variation of the process input variables (delivery condition and thus mechanical properties of the raw parts as well as the process parameters of rotational speed and feed rate). Here it can be shown that above all, the feed rate of the final forming process has the strongest influence on the process and thus also offers the strongest possibilities for influencing it.</jats:p>}},
  author       = {{Borgert, Thomas and Henke, Maximilian and Homberg, Werner}},
  issn         = {{2504-4494}},
  journal      = {{Journal of Manufacturing and Materials Processing}},
  keywords     = {{Industrial and Manufacturing Engineering, Mechanical Engineering, Mechanics of Materials}},
  number       = {{4}},
  publisher    = {{MDPI AG}},
  title        = {{{Investigations on the Influences of the Thermomechanical Manufacturing of Aluminium Auxiliary Joining Elements}}},
  doi          = {{10.3390/jmmp7040147}},
  volume       = {{7}},
  year         = {{2023}},
}

@inbook{46752,
  abstract     = {{Due to current global challenges regarding energy security as well as climate change the importance of preserving the nature and all available resources is steadily increasing. In order to achieve the energy-saving and climate targets, it is not only necessary to develop new processes and processing possibilities, but also to optimise known process chains with regard to energy and resource efficiency in the area of production technology. Here, the recycling of supposed production waste represents an opportunity to save energy. In addition to the conventional and smelting metallurgical recycling process, extensive research activities have therefore been carried out for alternative solid-state recycling processes. One example is the friction-induced recycling process, which has been used in past studies to demonstrate the energy- and resource-efficient production of semi-finished products from aluminium scrap such as chips. In addition, properties like chemical composition and strength can be adjusted locally and in terms of processing time. This can be used to improve the versatility of further processing steps.}},
  author       = {{Borgert, Thomas and Homberg, Werner}},
  booktitle    = {{Lecture Notes in Mechanical Engineering}},
  isbn         = {{9783031413407}},
  issn         = {{2195-4356}},
  publisher    = {{Springer Nature Switzerland}},
  title        = {{{Friction-Induced Recycled Aluminium Semi-finished Products in Thermo-mechanical Joining Technology}}},
  doi          = {{10.1007/978-3-031-41341-4_1}},
  year         = {{2023}},
}

@article{34216,
  abstract     = {{Mechanical joining technologies are increasingly used in multi-material lightweight constructions and offer opportunities to create versatile joining processes due to their low heat input, robustness to metallurgical incompatibilities and various process variants. They can be categorised into technologies which require an auxiliary joining element, or do not require an auxiliary joining element. A typical example for a mechanical joining process with auxiliary joining element is self-piercing riveting. A wide range of processes exist which are not requiring an auxiliary joining element. This allows both point-shaped (e.g., by clinching) and line-shaped (e.g., friction stir welding) joints to be produced. In order to achieve versatile processes, challenges exist in particular in the creation of intervention possibilities in the process and the understanding and handling of materials that are difficult to join, such as fiber reinforced plastics (FRP) or high-strength metals. In addition, predictive capability is required, which in particular requires accurate process simulation. Finally, the processes must be measured non-destructively in order to generate control variables in the process or to investigate the cause-effect relationship. This paper covers the state of the art in scientific research concerning mechanical joining and discusses future challenges on the way to versatile mechanical joining processes.}},
  author       = {{Meschut, Gerson and Merklein, M. and Brosius, A. and Drummer, D. and Fratini, L. and Füssel, U. and Gude, M. and Homberg, Werner and Martins, P.A.F. and Bobbert, Mathias and Lechner, M. and Kupfer, R. and Gröger, B. and Han, Daxin and Kalich, J. and Kappe, Fabian and Kleffel, T. and Köhler, D. and Kuball, C.-M. and Popp, J. and Römisch, D. and Troschitz, J. and Wischer, Christian and Wituschek, S. and Wolf, M.}},
  issn         = {{2666-3309}},
  journal      = {{Journal of Advanced Joining Processes}},
  keywords     = {{Mechanical Engineering, Mechanics of Materials, Engineering (miscellaneous), Chemical Engineering (miscellaneous)}},
  publisher    = {{Elsevier BV}},
  title        = {{{Review on mechanical joining by plastic deformation}}},
  doi          = {{10.1016/j.jajp.2022.100113}},
  volume       = {{5}},
  year         = {{2022}},
}

@article{31360,
  abstract     = {{<jats:p>The adaptive joining process employing friction-spun joint connectors (FSJC) is a promising method for the realization of adaptable joints and thus for lightweight construction. In addition to experimental investigations, numerical studies are indispensable tools for its development. Therefore, this paper includes an analysis of boundary conditions for the spatial discretization and mesh modeling techniques, the material modeling, the contact and friction modeling, and the thermal boundary conditions for the finite element (FE) modeling of this joining process. For these investigations, two FE models corresponding to the two process steps were set up and compared with the two related processes of friction stir welding and friction drilling. Regarding the spatial discretization, the Lagrangian approach is not sufficient to represent the deformation that occurs. The Johnson-Cook model is well suited as a material model. The modeling of the contact detection and friction are important research subjects. Coulomb’s law of friction is not adequate to account for the complex friction phenomena of the adaptive joining process. The thermal boundary conditions play a decisive role in heat generation and thus in the material flow of the process. It is advisable to use temperature-dependent parameters and to investigate in detail the influence of radiation in the entire process.</jats:p>}},
  author       = {{Oesterwinter, Annika and Wischer, Christian and Homberg, Werner}},
  issn         = {{2075-4701}},
  journal      = {{Metals}},
  keywords     = {{General Materials Science, Metals and Alloys}},
  number       = {{5}},
  publisher    = {{MDPI AG}},
  title        = {{{Identification of Requirements for FE Modeling of an Adaptive Joining Technology Employing Friction-Spun Joint Connectors (FSJC)}}},
  doi          = {{10.3390/met12050869}},
  volume       = {{12}},
  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{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{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{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{30713,
  author       = {{Rostek, Tim and Wiens, Eugen and Homberg, Werner}},
  journal      = {{Procedia Manufacturing}},
  pages        = {{395--399}},
  publisher    = {{ Elsevier Ltd}},
  title        = {{{Joining with Versatile Friction-Spun Joint Connectors}}},
  doi          = {{10.1016/j.promfg.2020.04.313}},
  volume       = {{47}},
  year         = {{2020}},
}