Modeling of high-power ultrasonic welding of Cu/Al joint

Ultrasonic metal welding is still an indistinct but useful manufacturing technology. A three-dimensional finite element model was developed to investigate this dynamic welding, including temperature rise, material deformation, and growth of intermetallic compounds. Heat generation at the upper and bottom interfaces, material softening, and high convection boundary conditions was considered. The results show that sonotrode tip teeth penetration starts earlier and increases rapidly, reaching the maximum, but anvil tip penetration starts later and increases slowly. The plastic deformation area of welding zone increases exponentially. Plastic strain is mainly generated in the welding zone, and the total plastic strain of welding zone is approximately proportional to the displacement of sonotrode tip. The thickness of intermetallic layer was dominated by ultrasonic action rather than interface temperature. The model was validated by comparing the predicted temperature, sonotrode displacement, and profile of weld cross section with the experimental results, exhibiting a good agreement.