Study of Mechanical Properties and Failure Mechanism of CFRP-Aluminum Alloy Self-Piercing Riveted-Adhesive Joints

The mechanical properties and failure mechanisms of self-piercing riveted-adhesive joints of carbon fiber-reinforced polymers/6061-T6 aluminum plates was investigated. The effects of riveting pressure, aluminum surface treatment, and lap length on the mechanical properties of the joints were analyzed. The microscopic morphology of the joint at each stage of the failure process was obtained by tensile-shear test and electron microscopy scan, on which the changes of CFRP, aluminum plate, rivet, and adhesive layer at different stages were further discussed to reveal the failure mechanism of the joint. The results showed that the joint strength could be improved by appropriately increasing the riveting pressure. The surface treatment of aluminum plate could improve the surface properties of the joint, and the joint strength showed a trend of first increasing and then decreasing with the increase of the sandpaper mesh. Increasing the lap length led to an increase in joint strength; however, when the lap length was increased to a certain value, the increase in joint strength was not obvious. The failure process of the adhesive riveted specimen was from the failure of the adhesive layer to the failure of the rivet, and after rivet failure, the joint failed completely.