Inverse Eigenstrain Analysis of the Effect of Non-uniform Sample Shape on the Residual Stress Due to Shot Peening

This paper deals with the analysis of elastic strain and eigenstrain in non-uniformly shaped shot-peened 17-4PH stainless steel samples. Based on residual strain measurements by synchrotron X-ray diffraction, the finite element (FE) models are established for the inverse problem of eigenstrain analysis in slice conical sample. The eigenstrains obtained in the slice are then implemented into the FE model of the solid conical sample. It is found that the dependence of elastic strain distributions on the peening intensity and sample shape/thickness could be elucidated via the understanding of underlying permanent strain, or eigenstrain. The effect of the peening process is therefore best described in terms of the induced eigenstrain. The proposed framework is useful for the predictive modelling of residual stresses in non-uniformly shaped shot-peened materials, in that it allows efficient reconstruction of complete residual stress states. In addition, it provides an excellent basis for developing predictive tools for in service performance and design optimisation.