铝/钢大功率超声波焊接过程模拟与试验验证

To reveal the mechanism of high-power ultrasonic welding, a three-dimensional thermal-mechanics coupling finite element model of high-power ultrasonic welding was established for predicting the interface temperature and materials plastic deformation in high-power ultrasonic welding 6061-T6 aluminum alloy to DC04 mild steel. The welding heat inputs were related to the ultrasonic power, while the materials ultrasonic softening was related to the welting vibration amplitude and frequency. The simulation results show that the rate of ultrasonic electric power converted into welding heats increases exponentially and then stabilizes. The maximum welding temperature is as 566 ℃, which reaches its 87% of the melting point of aluminum alloys. At the steel/aluminum interfaces, the materials plastically flow from the outside to the central area beneath the sonotrode, and accumulate around at the welding zones. This promotes the formation of welds, resulting in the area of the welded area being larger than that of the sonotrode. In addition, in the initial stage, the sonotrode penetrates into top surfaces of the steels. Subsequently, under the action of ultrasonic softening and high temperature, the speed of the anvil tips penetration into the aluminum alloy surfaces is accelerated. The penetrations depth of workpieces reaches maximum at the end of welding.