An experimental study on the tensile properties of metal-metal and polymer-metal T-joints grooved-bonded with structural adhesive

In order to improve the reliability and stability of out-of-plane joints, this study focuses on scrutinizing the surface characterization, mechanical properties and fracture response of similar and dissimilar adhesively-bonded T-joints which are very susceptible against tensile loading. Connections are manufactured in four different configurations: Al/Al, modified Al/Al, PA6/Al, and PA6-30GF/Al. Surface modification through the laser ablation treatment is applied to the vertical part and skin of AA7075 to increase the joint strength of similar joints. Fracture morphology analysis is performed to gain insight into the failure mechanisms. The experimental results indicate a substantial increase of approximately 27 % in the load-bearing capacity at the joint interface of Al-Al configuration due to the laser microtexturing. Furthermore, with the application of laser processing patterns, damage of the similar joints is transformed from mixed-mode failure (adhesion/cohesion failure) to cohesion failure at laser-treated surfaces. For dissimilar joints, PA6-30GF/Al joint with thin-film cohesive failure shows superior performance compared to PA6/Al connection with mixed-mode failure. The composite/metal connection offers a 38 % greater maximum load under the same conditions.