Three-dimensional simulation of finite element ultrasonic welding of aluminum alloy AA-6061

Ultrasonic metal welding is often used as a rapid and effective technique for joining sheet metals without causing them to melt. Precise management of the welding process parameters is crucial for achieving excellent joint quality. However, modeling the behavior of the weld material and the welding process is still very challenging. This study aimed to create 3D finite element models that accurately simulate the ultrasonic metal welding process. The proposed material model integrates frictional heat and ultrasonic softening, as well as the cyclic plasticity model. A friction law incorporating a variable friction coefficient is examined to investigate surface impacts. This coefficient is influenced by contact pressure, slippage, temperature, and the number of cycles. The findings of this study demonstrate that the oscillation frequency significantly influences both the temperature fluctuation and the extent of the heat-affected zone. Increased frequencies lead to accelerated temperature fluctuations and expanded heat-affected. Furthermore, ultrasonic welding combined with preheating led to a much wider heat-affected zone than ultrasonic welding without heating. The minimum preheating temperature required for ultrasonic welding of aluminum is 150 °C. This model can predict the relative displacement between welded plates. Assessing the oscillations that arise during the ultrasonic welding process is beneficial in selecting suitable welding settings to prevent excessive heating. This aids engineers in choosing appropriate welding parameters to avoid excessive heat generation during ultrasonic welding, hence limiting the reduction in tensile strength of the weld. Consequently, it can decrease the expense of the experimental methodology.