Mechanical properties and failure behavior of flow-drilling screw-bonding joining of dissimilar aluminum alloys under dynamic tensile and fatigue loading

Abstract

Flow-drilling screw (FDS) is a new type of single-sided joining process that is increasingly used to join dissimilar aluminum alloys in automobile lightweight. Fatigue failure and high-speed collision may occur in automotive joints under actual service conditions. This study proposed a joining process combining FDS and adhesive bonding to join dissimilar aluminum alloy sheets commonly used in body manufacturing. The adhesive bonding improved the joint strength and increased the failure distance of FDS joint. A thorough study of the FDS-bonding joining process on the mechanical properties and failure behavior was conducted. Specifically, a finite element analysis (FEA) model was built to predict the plastic deformation and stress distribution of the joints. Microstructure and hardness tests of the joints were performed to study the effect of plastic deformation during the joining process. The comparison of the mechanical properties and failure behavior of joints in dynamic tensile and quasi-static tensile tests showed differences and strain rate sensitivity. In addition, the maximum load–fatigue life (F-N) curves of dissimilar aluminum alloy joining were obtained by fatigue tests to predict the fatigue strength and failure life of the joints. Furthermore, the relationship between failure mechanisms and mechanical properties was established. This work provides a new industrial solution and failure performance reference for the requirement of composite structure and often one-sided access connection position in automobile industry.