Tensile-shear fatigue analysis and comparison of light alloy thin sheet lap-joints obtained by ultrasonic spot welding and ultrasonic spot welding plus adhesive bonding

The present research is part of the HY-LAP (HYbrid LAP-joints) project carried out at the Dept. of Mechanical Engineering of Politecnico di Milano in collaboration with the MUSP laboratory in Piacenza (Italy) and the University of Parma (Italy). In particular, the present study deals with the experimental characterization of the tensile-shear fatigue behavior of both spot welded lap-joints obtained by ultrasonic metal spot welding and hybrid lap-joints obtained by ultrasonic metal spot welding plus adhesive bonding. All the considered lap-joints were realized joining thin sheets made of AA6022T4 aluminum alloy or AZ31B magnesium alloy. A careful failure analysis is carried out on all the tested specimens and a comparison of the fatigue performance to other spot welding techniques is also presented.