Modeling of resistance heat assisted ultrasonic welding of Cu-Al joint

A three-dimensional thermal-mechanical-electrical coupling model for the hybrid welding of Cu-Al joint based on the finite element (FEM) method was established to investigate the effects of resistance heat on the ultrasonic welding (USW) process. Dynamic ultrasonic softening and heat generation related to the vibration amplitudes of specimens and sonotrode were considered. The simulation showed that the resistance heat could significantly increase the interface temperature, accelerate the penetration process of the teeth and promote the plastic deformation in the specimens. The resistance heat played an important role in the hybrid welding, and the USW process was greatly accelerated by the additional resistance heat. A thinner intermetallic compound (IMC) layer was obtained for the similar interface temperature distribution. The simulation results including the faying surface temperature, the sonotrode tip displacements and the weld joint profiles were found to be in good agreement with the experimental results.