Revisiting the design of the rivet chamfered ends in double-sided self-pierce riveting

As an innovative joining method, double-sided self-pierce riveting (DSSPR) shows great potential in sheet joining area due to its high connection strength, smooth joining surface, simple die structure, etc. By modifying the process, such as the use of rivets with different angles or two-stroke riveting method, dissimilar materials with great difference in mechanical property can be joined successfully. However, the chamfered angle is always at the outermost side of the rivet in previous studies, and its effect has not been paid attention to. In this paper, the chamfered angle position was proposed and studied as a design parameter of tubular rivet for the first time. DSSPR processes with a combination of three chamfered angles and five chamfered angle positions were carried out, and then a single-lap shear test was performed to evaluate the joint strength. Results showed that the chamfered angle position had a significant influence on the riveting force, final rivet morphology, shear strength, and failure mode. When the chamfered angle was 30° and 45°, the maximum shear force for the case of l=0.25 was 82.53% and 51.21% higher than that of the traditional tubular rivet, respectively. In addition, the failure modes during the DSSPR process were analyzed and summarized, and the development process of the three failure modes was discussed. The results can provide theoretical guidance for tubular rivet parameter design in the DSSPR process and its further engineering application.