Modeling the effects of ultrasonic vibration on friction stir welding

A mathematical model is developed to analyze the effects of superimposed ultrasonic vibration on heat generation, temperature distribution and material flow in friction stir welding process. Ultrasonic softening plays a dominant role in ultrasonic vibration enhanced friction stir welding process, while the thermal effect of ultrasonic vibration is insignificant. Superimposing ultrasonic vibration in friction stir welding process can produce an enhanced plastic material flow, increase the welding speed and welding efficiency, and also improve the weld quality by enhancing the plastic material flow near the tool. The model is validated by a comparison of the calculated thermal cycles and thermo-mechanically affected zone boundaries with the experimentally measured ones.