• Parametric study of three-sheet shear-clinching application classes • Inner punch diameter and outer-punch preload systematically varied • Force-displacement response linked to joint geometry • Joinability limits for DP1000 and X2CrNiMoN22-5-3 die-side materials • Guidelines for tool design in aluminum-steel three-layer sheet stacks The increasing use of high-strength and dissimilar sheet materials in lightweight structures requires element-free joining processes that meet demanding mechanical requirements. Shear-clinching combines cutting and forming to create a mechanical interlock by indirectly shearing the die-side sheet and displacing the punch-side sheet axially and radially. While process mechanisms are well understood for two-sheet joints, there is little fundamental knowledge on shear-clinching of three-layer sheet metal stacks. This study systematically investigates the influence of tool and process parameters on three-sheet shear-clinching of aluminum-steel combinations. The inner punch diameter is varied between 5.2, 5.4 and 5.6 mm with coupled outer punch chamfer widths that keep the outer chamfer diameter constant. For a selected punch configuration, the outer punch spring preload is adjusted to three discrete levels to modify the force-controlled offset between inner and outer punch and, in turn, the penetration depth of the outer punch into the stack. Three-layer stacks consist of AA5083 as the ductile punch-side sheet and either DP1000 or X2CrNiMoN22-5-3 as high-strength die-side sheets in two thickness levels. The process response is evaluated using force-displacement curves and joint cross-sections. The results show that the inner punch diameter is the primary design lever, systematically increasing joining and cutting forces and affecting the balance between interlock growth and neck thinning, whereas outer punch preload mainly sets the global load level. Joinability and achievable undercut remain strongly dependent on the application class and die-side material, highlighting the need for tailored tool designs for three-sheet shear-clinching of lightweight multi-material structures.
Neumann et al. (Sun,) studied this question.