Model for Predicting Laser Peening Residual Stresses in Arbitrary 3D Bodies

This paper presents a methodology for predicting the residual stress resulting from laser peening treatment of arbitrary 3D bodies. The model consists of three basic steps. First, the inputs to the model are derived from residual stress measurements made on laser peened blocks of the pertinent material. The measured residual stress in the blocks consists of residual stress caused directly by laser peening and residual stress required for equilibrium. The laser peening induced residual stress is converted into an equivalent strain distribution that reproduces the stress state in an elastic model of the original body (called eigenstrain). Second, a finite element model representing the geometry of the actual part is constructed. Third, the laser peening induced eigenstrain is input into the finite element model at the locations where laser peening is to be applied (arbitrary coverage area). Solving for equilibrium provides a prediction for the residual stress resulting from laser peening treatment. The modeling procedure is verified using comparisons with residual stress measurements for specimens containing corner fillets of various sizes. The model predictions correlate well with the residual stress measurements over the range of conditions studied.