Fatigue Failure Mechanism of Adhesive Joints Treated by Laser Patterning Surface Treatment

Abstract

This study investigates the effects of "laser patterning" using a fiber laser as a mechanical surface treatment for adhesive bonding. The influence of the fracture mechanism by the surface topography of the material was elucidated by strain measurement and observation of cracks during the fatigue test. From the results, it was found that there are two types of failure modes of adhesive bonding, one is the failure mode starting from delamination at the edge which is caused by the deformation of the adherend and the other is the failure mode starting from weak adhesion inside the adhesive around the edge. The laser patterning improved the fatigue strength of the adhesive because it prevented crack propagation near the interface and it increased adhesive area results in a stronger adhesion.