Potential of shear-clinching technology for joining of three sheets

The load-specific design of car bodies often requires the joining of more than two sheets. However, due to the additional interfaces and the mutual influence of the joining partners, joining of multi-layer sheets is challenging. This applies for welding technologies and in particular for joining by forming processes, which are often limited by the mechanical properties of the joining partners or require additional fasteners. The shear-clinching technology combines shear-cutting and clinching and therefore allows the joining by forming of high-strength materials without additional fasteners or pre-holing. Yet, the process has only been analyzed for two sheets. Thus, the potential of the technology for joining three sheets is investigated within the scope of this work. Starting from a two-sheet joint with punch-sided AA5182-O and die-sided DP600, the upper and the lower sheet are subsequently replaced by two sheets with half the thickness. The shear-clinching process, the joint formation and the resulting load-bearing capacity are analyzed for the joining of three sheets and compared to the two-sheet reference. Shear-clinching of three sheets with DP600 in the middle and the bottom layer was successfully conducted. Under shear load, the load-bearing capacity is comparable to the two-sheet specimens. However, applying tensile load leads to a two-staged failure of the joint and therefore to lower testing forces. When the force is applied to the top and the bottom layer, the joint strength is distinctly reduced, independent from the load direction