Modeling and investigation of pin geometry and vibration amplitude on the residual stress in ultrasonic hammer peening process

Ultrasonic hammer peening process is one of the new technologies of cold plastic deformation, in which a tool with high-frequency vibration impacts the surface of the workpiece and causes severe plastic deformation on the surface. Applying ultrasonic impacts to the material surface will increase the hardness of the surface, induce compressive residual stress, reduce the grain size, reduce the surface roughness and change the surface texture. In the process of ultrasonic hammer peening, the impacts are transferred to the workpiece through the pin. Therefore, pin specifications including geometric shape, length, diameter and impact angle are important in ultrasonic hammer peening process. The purpose of this article is to investigate the geometry of the pin and its effect on the amount and depth of stress by numerical simulation using Abaqus software. According to the modeling results, the maximum compressive residual stress and the depth of the compressive residual stress increased with the increase of the vibration amplitude. In the modeling of the ultrasonic hammer peening process, by increasing the diameter of the pin from 3 to 5 mm, the maximum compressive residual stress decreased and the stress depth increased. Also, increasing the pin tip radius has increased the compressive residual stress and decreased the stress depth.