Quasi-static and fatigue characteristics of self-piercing riveted joints in dissimilar aluminium-lithium alloy and titanium sheets

Abstract

The dissimilar self-piercing riveted (SPR) joints between aluminium-lithium alloy (AL1420) and titanium (TA1) sheets were investigated. The effects of the overlap form and rivet hardness on the forming structures, quasi-static and fatigue characteristics of the considered dissimilar joints were analysed systematically. A new curve-fitting method was adopted to fit the fatigue data of SPR joints. The results show that the potential weak areas in the forming structures could be changed using different overlap forms or rivet hardness. The overlap form for the dissimilar joints plays a more important role on the joint strength compared to the rivet hardness, but has little influence on the energy absorption. The fatigue property of the dissimilar joints is improved with the rivet hardness increased and the joints taken TA1 as the locked sheet possess a better fatigue life. The rivet hardness presents an obvious influence on the fatigue fracture path. The forming structures of the dissimilar joints are significantly affected by the overlap forms, which finally results in the fatigue fracture originated in different initiation sites.