Development of hybrid friction stir welding and adhesive bonding single lap joints in aluminium alloys

Aeronautical structures have been assembled for decades using a wide variety of welding and joining techniques. Over the last 15-20 years significant developments in joining techniques have occurred. Aluminium alloys have been the main traditional materials in civil aeronautical industry for the fuselage and structural parts. In order to reduce weight, improving fuel efficiency, there is the need to develop innovative solutions to join aluminium components in a single lap joint (SLJ) configuration with higher strength to weight ratio than riveting and fastening. In this work, a combination of the friction stir welding (FSW) and adhesive bonding (AB) processes is presented. Quasi-static mechanical properties, fatigue behaviour and other properties of the friction stir weld-bonding joints were assessed and compared with adhesive only and friction stir welded only joints. The development of this new joining technology, combining FSW with AB, resulting in friction stir weld-bonding, aims to incorporate properties and characteristics of both joining technologies, as well as improving damage tolerance. The present research involved the production of two types of overlap joints - FSW and hybrid friction stir weld-bonding. The main objective of this study is to compare the different joining technologies in lap joint configuration and evaluate the influence of different parameters on the mechanical behavior of the joints. The hybrid joints present higher strength, ductility and hardness, with the highest joint efficiency achieved in the hybrid joint produced with 450 kgf. These findings lead to the conclusion that -hybridization process confers a joint efficiency improvement between 20-30 % in most cases.