Damage mechanisms under tension shear loading in friction stir spot welding

Abstract

This paper investigates the fracture and damage of a single lap friction stir spot welding assembly formed from thin sheets of aluminium alloy 6082 T6. For fixed process parameters and tool geometry, two configurations are taken into account for the analysis of the global mechanical behaviour of the link. An experimental approach was carried out in order to analyse the sequence of damage mechanisms using acoustic emission and measurement of fields by digital image correlation techniques simultaneously. The acoustic emission technique allows the monitoring of the evolution of acoustic activities by taking into account energy of the events. The digital image correlation technique confirms the damage scenarios after the treatment of strain field at any point near the fastener and especially between the exit hole and the shoulder footprint. The coupling of those two techniques allows identifying characteristic points and a breakdown of the load displacement curve in phases.