Abstract: Structural constituent and hardness distribution of weld spot zone in the weldbonded joints are investigated. A computational model for weldbonded joints is established, which is composed os four parts, i. e. base metal ,heat affected zone, nugget and adhesive layer, and several structural details are taken into account in the model, making it more close to actual joint. Stresses in spot welded joints, adhesive bonded joints and weldbonded joints are calculated and studied using the computational model established. Finally, σ-N curves of these three types of joints are obtained by high frequency fatigue tests, fatigue behavior and fracture characteristics of the joints are studied. Results show that stresses from numerical analysis are identical with experimental results and phenomena. The application of adhesives in spot welding greatly improves the joint fatigue performance, while the presence of weld spots in adhesive bonding has negative effect on joint fatigue performance.

Key words: Computational model, Fatigue behavior, Weldbonded joint, σ-N Curves