Experimental and Numerical Investigation of Ultrasonic Welding of Steel/Aluminum/Steel Three-Layer Sheets and Its Application in the Engineering Finite Element and Numerical Computation Course

The aluminum/steel hybrid body structure represents one of the key breakthrough directions for automotive lightweighting. However, aluminum and steel differ significantly in their thermophysical properties, making it difficult to achieve high-quality joining between them using conventional fusion welding methods. To address this challenge, the present study employs ultrasonic welding technology to achieve spot welding in a steel/aluminum/steel three-layer plate configuration. The experimental welding of the three-layer sheets and interfacial phase identification were first carried out, followed by the development of an ultrasonic vibration–thermal–mechanical coupled numerical simulation model, the accuracy of which was verified through experiments. On this basis, the dynamic evolution of the temperature and stress fields during the ultrasonic welding process was systematically revealed. Furthermore, this novel engineering simulation case was introduced into the teaching of the course Engineering Finite Element and Numerical Computation yielding favorable educational outcomes.