Reinforcement and toughening of the self‐piercing riveted bonded joints induced by the pre‐embedded adhesive in rivet cavities

Abstract Self‐piercing riveted bonded (SPRB) joints are widely used in body‐in‐white (BIW) to connect dissimilar materials owing to their high fatigue and electrochemical performance. However, the strength of the SPRB joint has been found to be inferior to that of self‐piercing riveted (SPR) joints, owing to the reduction in undercut induced by the introduction of an adhesive, especially under pull‐out loading conditions. Interestingly, the mechanical strength improved when the rivet cavity was pre‐embedded with an adhesive. Before the riveting process, the rivet cavities in SPRB joints were pre‐embedded with 0.01, 0.02, and 0.03 mL of adhesive, namely them PSPRB‐V1–V3, respectively. Finite element (FE) models of SPRB and PSPRB joints were developed to analyze their formability and mechanical properties. The simulated and experimental results showed that the hydraulic pressure in the rivet cavity increased as the pre‐embedded adhesive volume in the rivet cavity increased during the riveting process, which further improved the undercut, microhardness, effective bearing area, and mechanical properties of joints. Among the prepared PSPRB joints, the PSPRB‐V3 joint exhibited the best undercut and optimal mechanical properties. Specifically, its undercut and peak force increased by 16.43% and 12.87% compared with those of SPRB joints. These findings provide important guidance for designing steel‐aluminum SPRB joints that require high‐bearing capabilities. Highlights The effect of pre‐embedded adhesive on the SPRB joint cross‐section was studied. Failure mechanisms of the SPRB and PSPRB joints were investigated via FEM. The better PSPRB joint performance over SPRB joints was elucidated. The stress–strain history was considered in the FE model of the joint failure process. Strengthening mechanism of pre‐embedded adhesive in the rivet cavity was discussed.