Inverse heat conduction model for the resistance spot welding of aluminum alloy

ABSTRACT

During the resistance spot welding (RSW), the thermal process plays a crucial role on nugget formation, especially the temperature field at the workpiece–workpiece interface, since it dominates the nugget diameter which is acknowledged generally as the quality criterion for welds, whereas it could hardly be measured experimentally. This work developed a solution for the RSW process of aluminum alloy according to inverse heat conduction problems. A direct transient heat conduction model was first established considering the variation of contact resistance with temperature and electrode force, the temperature-dependent thermophysical material properties, etc. A developed inverse model was then solved via the conjugate gradient method combined with the direct model based on the experimental temperature measurements at the workpiece surface by infrared thermometry. The calculated temperature distributions at the interface of workpieces were examined by the resulting development of the nugget diameter, which agrees well with the experimental results.