Structural design of half hollow rivet for electromagnetic self-piercing riveting process of dissimilar materials

Abstract Electromagnetic self-piercing riveting (E-SPR) as a new riveting method is attracting more and more attentions due to its superiority in joining dissimilar materials. In this paper, nine sets of half hollow rivets with different blade angles, inner diameters and leg lengths were designed for E-SPR process. The section quality and mechanical properties of the joints with these rivets for CFRP/Al and steel/Al structures were evaluated, and then the joints with optimal mechanical properties were analyzed by grey correlation theory. The results showed that rivet structures had a significant impact on the section quality of the E-SPR joints, and mechanical properties of the joints with different rivet types performed various. Specifically, in terms of shear load and energy absorption, the rivets with blade angle of 30° and inner diameter of 2.8 mm and the rivets with blade angle of 40° and inner diameter of 2.6 mm were the most suitable for CFRP/Al and steel/Al structure in E-SPR process, respectively. This was because these joints had moderate leg thickness and undercut simultaneously, which provided greater resistance in shear process. This study would provide an available reference for selecting half hollow rivet structures in different applications.