Influence of rivet structure on the bonding mechanism and mechanical properties of carbon fiber reinforced polyphenylene sulfide‐AA7075 friction stir blind riveted joint

Abstract This paper reports an experimental investigation into joining mechanism and mechanical properties of carbon fiber reinforced polyphenylene sulfide (CF/PPS)‐AA7075 friction stir blind riveting (FSBR) joints made of different structure rivets. Four types of rivets were obtained by second machining of the commercial rivet, the corresponding FSBR test were conducted. Penetration forces and temperatures during friction penetration process were collected. The joint quality, tensile shear strength, and failure mode of the four types of joints were compared. The results demonstrated that the joint quality and mechanical behavior of the FSBR joint were highly related with the rivet tip structure. Compared with the original commercial rivet, machining rectangular or triangular slots at the rivet tip can increase the cutting proportion during FSBR process, which will reduce material damage, penetration force, flash and the gap between the two workpieces. The premature mandrel breakage caused joining failure can be effectively avoided by introducing slots at the rivet tip. Rivet with four triangular grooves was the most effective, can reduce penetration force by 14.9%, increase joint tensile shear strength by 10.9% and increasing fatigue life up to five times that of original commercial rivet. Highlights FSBR technology is firstly applied to the joining of aluminum alloy with CFRTP. Rectangular or triangular slots are machined at the tips of commercial rivets. Forming quality, tensile strength, and failure mode of joints were evaluated. Probability of joining failure is effectively reduced. Joint tensile strength has increased by 10.9% and fatigue life up to five times.