Effects of ultrasonic vibration on the residual stresses generated during single-point incremental forming

In order to explore the effects of ultrasonic vibration on the residual stresses generated during single-point incremental forming, simulations and experimental verification were performed during this study. The relationship between the residual stress and the springback along the generatrix of a part, the residual stress variation trends in different directions along the thickness of the part, and the residual stress variation trends and spring-back in different regions of the part were investigated under the action of ultrasonic vibration. It was found that the amplitude of the wall residual stress varied significantly along the thickness direction in each region, while the circumferential residual stress exhibited a trend of decreasing tensile stress from the internal surface to the external surface along the thickness direction in each region. The normal residual stress, however, was too small and its variations were not obvious. After ultrasonic vibration was introduced, the maximum value of the circumferential residual stress decreased by 30.02 MPa, the maximum value of the wall residual stress decreased by 18.84 MPa, and the minimum deviation between the actual sidewall angle and the theoretical sidewall angle reached 0.42 degrees. The springback suppression effect was improved by 44.08 %. These results indicate that ultrasonic vibration can effectively reduce residual stresses and suppress part spring-back. These results are attributed to the fact that ultrasonic vibration changes the forming mechanism and improves the plasticity and ductility of the metal, which are of great significance with respect to part quality and accuracy improvements.