Physical property and failure mechanism of self-piercing riveting joints between foam metal sandwich composite aluminum plate and aluminum alloy

Abstract

Self-piercing riveting is a promising method to join thin-wall structures in the automobile industry, especially for the connection of different materials. Due to their excellent strength-to-weight ratios and vibration/noise reduction characteristics, foam metal sandwich composite aluminum plates are the best choices for modern automobiles. In this paper, the self-piercing riveting forming qualities and joint strengths of foam iron-nickel/copper sandwich composite aluminum plates with AA5052 aluminum alloys are investigated, and the fracture morphologies of tensile failure samples are characterized. The results showed that: the foam metal sandwich composite aluminum plates can increase the interlock width and improve the self-locking performance of the joints, and the bottom thicknesses are significantly increased when the foam metal sandwich composite aluminum plates are riveted as the bottom plates. In the tension-shear tests, the foam sandwiches reduce the maximum failure loads and increase the maximum failure displacements of the joints. Moreover, the macro/micro-structure characteristics of the foam metal sandwich composite aluminum plates affect the failure modes of the joints. When the foam metal sandwich composite aluminum plates are used as the top plates, the failure mode is that the composite aluminum plates break down in the direction perpendicular to the loading of the plates. When they are riveted as the bottom plates, the failure mode is that the rivets are entirely pulled out from the bottom base plates of the composite plates, partially separated from the foam metal sandwich composite aluminum plates, and the top base plates and the sandwich metals are torn apart at the same time.