PSI - Issue 73

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Jakub Flodr et al. / Procedia Structural Integrity 73 (2025) 9–13 Jakub Flodr, Petr Lehner, Dominik Gřešica, Martin Krejsa / Structural Integrity Procedia 00 (2025) 000–000

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the input for these lines was steel coils. If the portfolio of thin-walled sections offered is designed to minimize the number of different input materials, i.e. the number of different widths or rolls is minimized, then a high degree of variability in the production of possible sections is ensured. Automation can then be improved by an alternative method of joining, e.g. a clinch joint, which is a method without adding additional material (Lambiase and Di Ilio, 2014; Lei et al., 2019; Varis and Lepistö, 2003). It is clear from previous research that the clinch joint is also suitable for building structure systems. Since a standard for the design of such a joint is still missing, the authors of this article have prepared a simple methodology based on the team's experimental and numerical studies (Flodr et al., 2020, 2019, 2017). The methodology of manual design of clinch joints is associated with one major complication. Without cross sectional analysis to determine the exact shape and geometry, the assumptions for manual design cannot be established. The following mandatory assumptions are made for the development and subsequent application of the methodology: • the clinch joint is manufactured technologically completely correctly and according to the recommendations of the technology manufacturer, • sufficient quality control must be ensured in the production process, for example, the couplings are tested by non-destructive methods, by measuring the so-called X1 value, • joint failures due to poor joint compactness because of the separation of the individual parts of the sheets to be joined without breaking the joint are avoided, • joints fail under shear and tensile loads at the weakest point - the neck, • actual material characteristics of the materials to be joined are available to the designer. 2. The simplified calculation 2.1. Initial assumptions The manual assessment is based on the analysis of the shape of the clinch joint from the cross section of Fig. 1. The weakest point among the analyses performed was always the so-called neck.

Fig. 1. Graphical representation of an equivalent cross-section for manual design of a clinch joint under shear load.

It is necessary to distinguish which type of stress is involved. In the case of shear stress, failure occurs roughly in the middle of the neck. Shear failure of the clinch joint is specific because of the eccentric loading and the generation of additional moments. In the case of a tensile failure of a clinch joint, the failure is always initiated at the weakest