Effects of die type on mechanical performance and failure behaviors of self-piercing riveting joints in AA5052

This study investigates the effects of self-piercing riveting (SPR) die type on the joint quality and failure modes of AA5052 SPR joints. Three die types: flat, pip, and ball-shaped were designed and processed for the SPR process, and 30 riveted specimens were prepared. A 2D axisymmetric finite element (FE) simulation model was established using LS-Dyna to evaluate the impact of each die type. The accuracy of the FE model was validated by comparing simulated joint cross-sections with experimental results. Subsequently, the quality and forming mechanisms of the SPR joints fabricated using each die type were analyzed. Mechanical properties were assessed through peak load and energy absorption during single-lap shear testing. Moreover, the macroscopic failure modes were observed via scanning electron microscopy (SEM) to determine failure modes. Results showed that specimens produced with the flat-type die exhibit the highest interlock value and mechanical properties. However, their forming quality is lower than those of the pip-type die due to the higher rivet head height. The pip die enhances rivet flaring, yielding mechanical properties superior to the flat-type die specimens. In contrast, specimens formed with the ball-shaped type die exhibit the lowest forming quality and mechanical performance. All specimens shared a rivet pull-out failure mode, though the degree of rivet hole deformation varied with riveting quality; the higher the quality, the greater the rivet hole deformation.