Analysis of aluminum resistance spot welding processes using coupled finite element procedures

A comprehensive analysis procedure has been developed to perform the incrementally coupled thermal-electrical-mechanical analysis to simulate the resistance spot welding process of aluminum alloys. Because aluminum has high thermal conductivity, low melting temperature and low yield strength, deformation resulting from resistance spot welding is expected to be more severe than for steel. Compared with most of the published work in this area, this paper takes into account the incremental changes in sheet-deformed shape, contact area and current density profile as well as large deformation effects. The present analysis procedures consider electrical contact resistivities to be not only functions of contact temperature but also functions of pressure. Joule heating at the contact surfaces is computed using an equivalent surface heat generation concept. This new procedure is suitable for analyzing many important parameters such as contact area changes, electrode movement and dynamic resistance, as well as other factors that contribute to weld quality such as weld size, weld indentation, sheet separation and weld residual stresses. It can also be used to study nugget development and analyze the mechanisms of electrode wear and weld cracking.