Effect of the joining temperature on the tensile–shear mechanical properties of clinch-adhesive joints in steel and aluminum alloy sheets

Given the temperature dependence of the performance of polymer-based adhesives, a warm clinch-adhesive joining technique, aimed at enhancing the formation quality of dissimilar material joints between steel and aluminum, was proposed in this study. The temperature-sensitive epoxy resin Araldite${}^{}$® 2015 was selected as the adhesive. Clinching was implemented at four different process temperatures, i.e., $25^{\circ }$C, $50^{\circ }$C, $65^{\circ }$C and $80^{\circ }$C, and the mechanical response of the joints was comprehensively assessed through tensile–shear tests at room temperature. Additionally, a finite element model of the clinch-adhesive joints subjected to tensile–shear loading at room temperature was developed to investigate the failure mechanism. The results revealed that increasing the process temperature to $80^{\circ }$C effectively promoted plastic flow of the adhesive layer and significantly enhanced the formation of mechanical interlocks, with an increase in the interlock depth of 22.9%; furthermore, the energy absorption capacity of the joint upon adhesive layer failure increased by 53.9%, and the peak load capacity increased by 16.8%.