@article{65373, abstract = {{To reduce CO₂ emissions, the automotive industry is adopting multi-material structures. Fusion-based joining reaches its limits for aluminium–steel due to brittle intermetallic phases and mismatched thermophysical properties; therefore, mechanical joining (e.g., SPR) is used. Though conventional SPR requires tool changes for different stack-ups. Versatile self-piercing riveting (V-SPR) addresses this with an extended punch actuator and a multi-range-capable rivet (Kappe in PERD16:363–378, 2022), enabling joints up to 600 MPa across varying thicknesses without retooling. With the use of ultra-high-strength steels up to 1000 MPa, optimisation is required. This study quantifies how rivet shank geometry affects joint formation using a design of experiments and validated 2D axisymmetric FE simulations. The optimum depends strongly on the material system. For CP1000–EN AW-6014, maximum interlock f is predicted for a medium shank thickness of about 0.73 mm, a small internal foot radius of 0.620 mm, and a deeper drill depth of 3.136 mm, yielding f fc =0.4503 mm with a desirability of 0.954. For EN AW-6014–EN AW-6014, the optimum shifts to a thinner shank of 0.670 mm, a larger internal foot radius of 0.820 mm and a shallow drill depth of 2.30 mm, giving ffc = 0.3023 mm with a desirability of 1.0. A compromise geometry of 0.713 mm shank thickness, 0.776 mm internal foot radius and 2.755 mm drill depth achieves ffc = 0.3641 mm for CP1000–aluminium and ffc = 0.1851 mm for aluminium–aluminium with an overall desirability D = 0.6378, expanding V-SPR to ultra-high-strength steel–aluminium joints while maintaining aluminium joinability.}}, author = {{Kaimann, Pia Katharina and Ritter, Nico and Bobbert, Mathias and Meschut, Gerson}}, issn = {{2731-6564}}, journal = {{Discover Mechanical Engineering}}, number = {{1}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Influence of the shank geometry on the joint formation of the versatile self-piercing riveting of ultra-high-strength steel-aluminium and aluminium-aluminium assemblies}}}, doi = {{10.1007/s44245-026-00221-y}}, volume = {{5}}, year = {{2026}}, } @article{65620, abstract = {{Abstract The design of clinch joints is a cost- and time-intensive iterative process due to the complex relationships between tool and process parameters and the resulting joint properties. To address this, this contribution proposes a novel hybrid workflow that combines knowledge- and data-based approaches. Relationships are categorized based on their knowledge quality and the need for a quantitative prediction. Well-established, generalizable relationships are formalized in an ontology as design guidelines (no quantification required) or SWRL rules (quantification required) to model expert knowledge. In contrast, hard-to-formalize or not-fully-understood relationships are treated with regression models for continuous or classification models for binary criteria. These approaches are combined in a generic user interface (GUI), where the ontology can be accessed using predefined SPARQL queries to select and adapt parameters using expert knowledge. These parameters are then used as input for the metamodels. The developed workflow is evaluated on two exemplary joining tasks to illustrate, how designers can retrieve similar prior joints, adapt parameters using the encoded design rules and predict resulting joint properties under varying process conditions. In summary, the combination of ontology and metamodels facilitates the transition of trial and error into an efficient, documentable design process.}}, author = {{Einwag, Jonathan-Markus and Wiemer, Maximilian and Wartzack, Sandro and Goetz, Stefan}}, issn = {{2731-6564}}, journal = {{Discover Mechanical Engineering}}, number = {{1}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{A hybrid knowledge based and data based approach for efficient clinch joint design}}}, doi = {{10.1007/s44245-026-00230-x}}, volume = {{5}}, year = {{2026}}, } @article{66622, abstract = {{Abstract The increasing use of thin-walled profiles in automotive battery housing construction is leading to a growing demand for one-sided access mechanical fasteners. Currently, the installation of blind rivet nuts still requires pre-drilling using chip-forming operations. In Meschut and Meyer (Vorlochfreies Setzen von Funktionselementen mittels Fließformen, Europäische Forschungsgesellschaft für Blechverarbeitung e.V. (EFB), Hannover, 2021), a chipless, two-step method for installing blind rivet nuts was developed, in which flow-drilling is the initial step. To eliminate the pre-drilling operation and optimise the joining process of blind rivet nuts, a pilot-hole-free joining method using a flow-drilling process is being pursued. The use of these blind rivet nuts can significantly simplify the joining process by eliminating chip-forming pre-drilling operations. Additionally, the screw-through capability reduces screw variance in automated fastening, optimising the feeding process by minimising the risk of incorrect screw selection. This work aims to develop a single-step process for the installation of a blind rivet nut. To achieve this, it is necessary to design the geometries of both the blind rivet nut and the flow-drill former, which also serves as the mandrel for the blind rivet nut. In addition to the geometries of the tools and functional elements, the flow-drilling process itself has been developed. Special attention is given to the pull-through and the formation of the closing head. To optimise the closing head formation, an iterative optimization process was used. The quality of the pull-through is improved by varying the tip geometries and adjusting the process parameters during flow-drilling.}}, author = {{Böhm, Yannic and Meschut, Gerson}}, issn = {{2731-6564}}, journal = {{Discover Mechanical Engineering}}, number = {{1}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Single-stage setting of blind rivet nuts without pre-drilling}}}, doi = {{10.1007/s44245-026-00222-x}}, volume = {{5}}, year = {{2026}}, } @article{66457, abstract = {{Abstract The service life of fatigue-loaded components that already contain manufacturing‑induced microcracks is primarily governed by the direction and the rate of fatigue-crack growth. When multiple loading components (e.g., tension, compression, shear) act simultaneously but not in temporal synchrony, out‑of‑phase mixed‑mode conditions occur. Such loadings are typical for automotive chassis parts and mechanically joined sheet‑metal assemblies. For optimized design of structural components, the crack kinking angle that occurs under mixed‑mode loading must be predicted as accurately as possible. At present, however, this is still challenging for out‑of‑phase loading conditions. To investigate the associated crack kinking behavior, a novel Compact‑Tension‑Shear‑Mini (CTSM) specimen was developed, enabling controlled generation of plane out-of-phase mixed-mode loading states. Experiments were performed under various combinations of cyclic and static mode I and mode II load components and compared with the analytical predictions of the Out-of-Phase Mixed-Mode (OMM) concept. The measured crack kinking angles showed very good agreement with the predicted values, with mean deviations of only a few degrees, demonstrating the validity and reproducibility of the approach. These findings confirm the applicability of the OMM concept for describing fatigue‑crack propagation under non‑proportional mixed‑mode loading and provide a basis for fatigue‑life assessment of clinched joints and other cyclic multi-axially loaded components.}}, author = {{Krome, Sven and Kullmer, Gunter and Weiß, Deborah and Duffe, Tobias and Ostwald, Richard}}, issn = {{2731-6564}}, journal = {{Discover Mechanical Engineering}}, number = {{1}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Experimental determination of kinking angles with out-of-phase mixed-mode loading by means of a novel specimen geometry}}}, doi = {{10.1007/s44245-026-00236-5}}, volume = {{5}}, year = {{2026}}, }