A sequential DEM-FEM coupling method to predict the ultrasonic shot peening of fir-tree shaped grooves in aero-engine turbine disk

Ultrasonic shot peeing (USP) is a random and uniform peening process that has advantage to strengthen the complex surface of fir-tree shaped groove. However, due to the complexity of the groove geometry, it is difficult to accurately predict the shot dynamics and surface integrity along the profile during USP treatment. In this paper, a coupled discrete element method (DEM) and finite element method (FEM) has been established to predict the ultrasonic shot peening process of the fir tree shaped groove. DEM simulation model is established with a real groove to obtain the velocity field of the shots. The shot dynamic field is coupled as an input to the FEM model to obtain the surface integrity. The USP experiment verifies that the proposed coupled method can predict the surface integrity of grooves. The compressive residual stress (CRS), maximum CRS, and roughness of each region obtained in the DEM-DEM model are relatively uniform (fluctuating within ±60 MPa). Further, the roughness of each area of the groove is below Ra0.6 μm, and the values is closely corresponded to the velocity field of the shot impact. This study provides an effective method and potential application in uniform surface strengthening of complex components.