Effect of locking mode on mechanical properties and failure behavior of CFRP/Al electromagnetic riveted joint

Electromagnetic riveting (EMR) has advantages in joining dissimilar materials due to the stable forming and uniform hole expansion. In this paper, CFRP and Al sheets were joined in three ways by EMR: slug rivet (SR), round head rivet (CFRP sheet was placed on the round head side, RC) and round head rivet (Al sheet was placed on the round head side, RA). The deformation characteristics, mechanical properties and failure behavior of the joints in above three locking modes were studied. Cross section observation, shear test and failure analysis were conducted. The results showed that the locking mode and discharge energy had obvious effects on the performance of the joint. The SR joint has stable deformation and the most uniform interference. RC joint had fewer microdefects and better mechanical properties. Furthermore, the weight analysis results showed that the weights of locking mode and discharge energy on shear property were 0.6647 and 0.3353, while that was 0.6149 and 0.3851 on energy absorption performance. In general, SR, RC and RA joints had their own characteristics, and the locking mode could be selected according to actual requirement. This study could provide guidance for the application of these CFRP/Al structures in automotive.