DEM-FEM coupling simulation of residual stresses and surface roughness induced by shot peening of TC4 titanium alloy

An integrated DEM-FEM coupling simulation approach is developed to simulate the real process of shot peening, and is validated by comparing the predicted in-depth residual stresses with the experimentally measured results. Two kinds of three-dimensional finite element models associated with the original surface roughness of Rα0 = 26.7μm and 50.1μm are respectively established by using Gaussian distribution in conjunction with the exponential autocorrelation function, and another target model without the original surface roughness is utilized for reference purposes. Taking advantage of the integrated DEM-FEM coupling simulations of shot peening processes based on the three kinds of target models, the effects of the original surface roughness, shot impact angle, and shot peening coverage on the shot-peened residual stresses and surface roughness are investigated in detail. The obtained results show that the larger original surface roughness of TC4 titanium alloy could be reduced by shot peening, and the reduction increases with the increasing shot peening coverage from 100 to 200%. In the target models associated with the original surface roughness, the distributions of shot-peened surface residual stresses tend to be more uniform than that in the target model without the original surface roughness, whereas both the in-depth residual stresses and surface roughness are not very sensitive to the changes of shot impact angle in the range from 60° to 90°.