Eigenstrain-based model for prediction of laser peening residual stresses in arbitrary three-dimensional bodies Part 1: Model description

This paper presents a methodology for predicting the residual stress within three-dimensional parts caused by laser peening treatment. The inputs to the model are the elastic material properties and shape of the part as well as an eigenstrain (also called ‘initial strain’ or ‘stress-free strain’) field specific to the material and parameters of laser peening treatment. The eigenstrain field is known from a library of fields developed prior to the residual stress prediction, either from detailed physical process modelling or from residual stress measurements of simple coupons of the parent material subject to the same laser peening treatment. The eigenstrain is assumed insensitive to part geometry, depending only on the part material and the laser peening treatment parameters. Given the eigenstrain field, residual stress is predicted by an elastic finite element analysis of the part that includes its detailed geometry and material composition. The eigenstrain is input into the finite element model in stated treatment areas where laser peening is applied. Solving for stress equilibrium provides an estimate of the residual stress field at all points within the treated part. The proposed modelling procedure is verified through a test on flat-plate geometry, where measured residual stress compares favourably with model predictions. In addition, the model is used to predict the residual stress produced by laser peening of a specimen containing a corner fillet. A companion paper (Part 2) presents detailed experimental verification of the model over a range of common part geometry.