Mechanical properties and fatigue behavior of electromagnetic riveted lap joints influenced by shear loading

Electromagnetic riveting (EMR) has gained increasing attention as a relatively new mechanical joining technique in automobile industry. In this paper, the mechanical properties and fatigue behavior of electromagnetic riveted lap joints are discussed systematically. The rivet deformation, microstructure and hardness distribution of the formed rivets were investigated, which were also compared with regular pressure riveting (RPR). The results of shear strength showed that there was almost no difference between EMR and RPR, and the fatigue performance of EMR was about 1-3 times higher than that of RPR at any cyclic stress level. Quasi-static fracture analysis showed that shear fracture occurred in rivet shaft and the rupture appearance of two processes was similar. For fatigue failure, there were two fatigue failure modes for both processes: rivet shaft fracture under a higher cyclic stress and manufactured head fracture under a lower cyclic stress. Under the higher cyclic stress level, there was no big difference between two processes in the fatigue appearance. However, the fatigue cracks propagation zone of EMR sample fracture was significantly wider than that of RPR under a lower cyclic stress level, indicating a higher fatigue life of EMR samples.