The effects of residual stresses on the fatigue life of 5083-O aluminum alloy spot welded joints

Abstract

In this study, resistance spot welding (RSW) process of 5083-O Aluminum alloy has been simulated numerically using an axisymmetric model of electrodes and sheets, and then the effects of residual stresses have been investigated on the fatigue life of the joints. All process parameters except electrode clamping force have been considered to be constant during RSW. Three different electrode force level have been considered and then dimensions of nuggets, HAZ and gaps have been obtained numerically. Three kinds of spot welded models with three different gap values between sheet joints have been simulated using Ansys code. Non-linear analysis was performed to obtain the local stress and strain ranges and then, Morrow equation with particular consideration of residual stress and gap distance effects has been applied to estimate fatigue lives. The results show that, with increasing the electrode force, the gap values between sheet joints increase. The results also reveal that the center region and the roots of nuggets have surrounded by the relatively large amounts of tensile residual stresses and also increasing the electrode force, reduce the amounts of residual stresses. The comparison between numerical results of fatigue lives and experimental data provided good agreement between numerical predictions and experiments.