Joining mechanism and damage of self-piercing riveted joints in carbon fibre reinforced polymer composites and aluminium alloy

The joining mechanism and damage of self-piercing riveted joints in carbon fibre reinforced polymer (CFRP) composites and aluminium alloy were investigated. The damage constitutive model for composite materials, considering the shear effect, was proposed to predict the mechanical behaviour and damage evolution of the CFRP. Self-piercing riveting (SPR) tests were performed to determine the damage patterns of joints with different laminate structures. Furthermore, numerical simulations of the SPR process were performed to understand the joining mechanism and analyse the damage evolution process of the joints. The results show that matrix cracks and fibre cracks existed in the SPR joints in the CFRP and aluminium alloy, located around the rivet head. With the increase in CFRP thickness, the damage degree of the joint surface decreases. Therefore, the proposed constitutive model can predict the complex damage behaviours of a CFRP subjected to large deformations. The matrix cracks are mainly caused by the matrix tensile damage, with the ply angle influencing the damage evolution trend. In addition, delamination exists between each ply of the SPR joint; the propagation direction of delamination damage is consistent with the fibre direction of the lower layer, especially for the joints with [0/90/0], CFRP or [45/-45/45], CFRP.

Automated summary

This study investigates the joining mechanism and damage of self-piercing riveted joints in carbon fibre reinforced polymer (CFRP) composites and aluminium alloy. A damage constitutive model, accounting for shear effects, is proposed to predict the mechanical behavior and damage evolution of CFRP. Self-piercing riveting (SPR) tests and numerical simulations are conducted to determine the damage patterns and understand the joining mechanism and damage evolution process of the joints. The results show the existence of matrix cracks and fiber cracks around the rivet head in the SPR joints of CFRP and aluminium alloy. The proposed constitutive model can effectively predict the complex damage behaviors of CFRP under large deformations. The direction of delamination damage propagation is consistent with the fiber direction of the lower layer in the SPR joints.