Several modifications have been made on friction stir welding process to overcome some certainlimitations which have been reported. One of these modifications is to use ultrasonic energy as an assistance tool in FSW process. In the present paper, a mathematical model is developed to express the heat generation during ultrasonic vibration enhanced friction
stir welding process (UVeFSW). A finite element model is built to perform a transient thermal heat transfer analysis using ANSYS mechanical APDL software package. The temperature contours, temperature distribution and the thermal cycles were predicted using the moving heat source technique. To validate the model, k-type thermocouples were used to measure the temperature and thermal cycles at five locations. The results showed a good agreement between the simulated and experimentally measured results.