Effect of laser patterning preprocessing on fatigue strength of adhesive bonded joints using thin steel plate

It is necessary for automobiles to reduce the weight of car bodies against environmental problems. As a countermeasure, a multi-material structure is required to construct the automobile body structure using not only steel but also light metal materials and carbon fiber reinforced plastic. So, it is necessary to produce high-quality welds applying to those dissimilar materials, as quickly as possible. Therefore, adhesive bonding has attracted attention from the viewpoint of building multi-material structures. However, from the viewpoint of durability and reliability, it is regarded as a complementary technique for other industrial welding methods. Moreover, to further improve the strength of adhesive bonding, the surface condition of the adherent is important. In this study, in order to improve the interfacial strength of adhesive bonded joint, the laser patterning preprocessing was applied as the surface treatment. So, the fatigue properties of adhesive bonded joints were evaluated to compare the untreated joints. As a result, the static and fatigue strength of the joints were improved by the laser patterning preprocessing. In particular, the joint strength was further improved by removing the weak boundary layer on the entire surface with the laser irradiation. Therefore, the laser patterning preprocessing proposed in this study is a very useful process for achieving the adhesive bonded joints with excellent fatigue properties. ©2019 The Society of Materials Science, Japan