Low-velocity impact response of self-piercing riveted carbon fiber reinforced polymer-AA6061T651 hybrid joints

Self-piercing riveting (SPR) is an effective method to join dissimilar materials, such as composite and aluminum alloy. In this paper, the dynamic loading response and the impact damage mechanism of carbon fiber reinforced polymer (CFRP) laminates and AA6061-T651 self-piercing riveting joints were investigated using the drop weight tests at energy levels between 7.5 J and 20 J at room temperature. The effect of diverse damage mechanisms on the impact resistance and quasi-static mechanical properties of the SPR joints were evaluated. The results showed that the low-velocity impact position has a great influence on the strength of SPR joints, and the strength of the joints is seriously decreased when impacted at the center of the rivet. There are two impact damage mechanisms. One was the internal damage of CFRP laminates and it was the dominant damage mech-anism before the impact energy of 10 J. Another one is the plastic deformation of aluminum alloy when the impact energy was above 10 J. The composite damage played a leading role in the absorption of the impact energy. Moreover, the impacted joints present residual strengths of 83 % (5 J), 76 % (7.5 J), 71 % (10 J), 57 % (12.5 J), 51 % (15 J), 48 % (17.5 J), 38 % (20 J) of the non-impact SPR joints. The axial impact resistance was more sensitive to the plastic deformation of aluminum alloy, while the quasi-static mechanical properties were more sensitive to the internal damage of CFRP.