Experimental measurement and analytical determination of shot peening residual stresses considering friction and real unloading behavior

This paper presents an analytical model to predict the residual stress distribution induced by Shot peening. The analytical approach is based on the work of Shen and Atluri (2006) [18] with some modifications. The modifications are related to the elasto-plastic unloading of shot impingements, friction coefficient effect and the fraction of kinetic energy transmitted to the treated material. In order to predict more realistic residual stresses, the elasto-plastic unloading phase of shot impacts is modeled using two nonlinear kinematic hardening models considering the Bauschinger effect. Moreover, the effect of the Coulomb friction between target surface and shots is evaluated. For this purpose, the interior stresses caused by tangential tractions of friction force are determined analytically. In this work, the effects of friction coefficient, hardening model in loading and unloading phases, the offset of determination of the yield points and the Bauschinger effect on the residual stress distribution are taken into account. Experiments are carried out on DIN 1.6582 medium carbon steel to validate the results obtained from the analytical model. The results of the comparison indicate that the analytical relations agree well with the experimental data.