Finite element analysis of heat generation in dissimilar alloy ultrasonic welding

Abstract

This paper presents a computationally efficient finite element analysis of the heat generation in ultrasonic welding (USW). The temperature field is predicted from a continuous thermal model, with the heat generation rate being calculated intermittently, using a deformation model for single cycles of oscillation. The model was applied to USW of Al 6111 to itself, and to DC04 steel and Ti6Al4V, with plastic deformation only occurring in the Al alloy. Ultrasonic softening was allowed for empirically in the constitutive plastic response of the Al alloy. The predicted heat generation rate for all three material combinations was consistent with that inferred from thermocouple data and the thermal model. Material deformation maps were developed as a means of illustrating the dominant deformation regime of temperature and strain-rate. The thermal and deformation models were then fully coupled, as a proof of concept, to demonstrate that the power and temperature histories can be predicted directly from the constitutive data for the alloy and a kinematic description of the process.