Aluminium Friction-stir Weld-bonded Joints

Abstract

A push towards more energy-efficient transport solutions has led to an increasing lightweight trend in structural design, requiring new materials, manufacturing, and assembly processes. The development of solid-state welding techniques, such as friction-stir welding (FSW), and the continuous improvement of adhesive technology, has created opportunities for new structural design concepts. Although FSW is capable of producing sound defect-free welds with high tensile strength efficiency in butt joint configuration, in the case of lap joints, the formation of a “hook”-like defect results in worse properties than base material. The combination of adhesive bonding (AB) with FSW aims to overcome this issue and create a hybrid joining technique. This work aims to develop a hybrid technique combining FSW and AB aggregating static strength testing and numerical modelling efforts. AB joints showed a 60% higher strength than FSW lap joints, but when combining FSW with adhesive, the hybrid joint managed to match the adhesive joints strength. Finite elements method (FEM) models developed for both AB and FSW lap joint showed some level of agreement, but when attempting to combine both models to discretize the hybrid joints the developed model failed to mimic the more complex failure mode.