Physics-Based Prediction of Residual Stresses for Fatigue and Fatigue Crack Growth Life Assessment

Surface enhancement processes such as conventional shot peening (SP) and laser shot peening (LSP) processes imparts compressive stresses on the surface of the components, which helps to improve the fatigue life. But, overpeening of the component might introduce undesired tensile stresses near the sub-surface of the component, which may promote accelerated fatigue damage and fatigue crack growth behavior. During Phase I part of this project, we propose to investigate appropriate modeling techniques for modeling laser shot peening process and identify the requirements for developing a robust and computationally efficient model. We propose to extend the existing conventional shot peen modeling capability in finite element method based process modeling system, DEFORM to include sensitivity analysis and demonstrate the impact of variabilities associated with the shot peen processing conditions on the predicted surface residual stress profiles. Predicted surface stress profiles will be passed on to DARWIN. We will demonstrate the feasibility of linking DEFORM near surface stress predictions from conventional shot peen process with DARWIN’s life and risk assessment models. Additionally, we will investigate appropriate damage models in the assessment of fatigue life due to surface treatment process such as conventional shot peening and laser shot peening processes.