Numerical simulation and experimental study of ultrasonic vibration-assisted laser polishing of Ti-6Al-4V alloy

Currently, the application of ultrasonic vibration-assisted machining in the process of laser processing has garnered significant interest for its potential to enhance machining efficiency and quality. This study introduces ultrasonic high-frequency vibration into the laser polishing process, establishing a two-dimensional transient numerical simulation model that couples heat transfer, fluid flow, and pressure acoustics. Additionally, experiments were conducted to analyze the effects of ultrasonic vibration on the temperature field, velocity field, and laser molten pool size during the laser single-track scanning polishing of Ti-6Al-4V alloy. The results indicate that ultrasonic vibration enhances the flow velocity of the molten pool during laser polishing, promotes convective heat transfer between the molten pool and its surroundings, and leads to a more uniform temperature distribution, thereby reducing the peak temperature of the molten pool. Furthermore, the introduction of ultrasonic vibration results in an increased molten pool width and a decreased depth, leading to an increased "width-todepth ratio." Without ultrasonic vibration assistance, the relative error between the simulated molten pool width and depth from the numerical model and the experimental results does not exceed 12 %. With ultrasonic vibration assistance, the relative error between the model and experimental results for the molten pool depth and width does not exceed 5 %, demonstrating the high accuracy of the model.