Physics-Based Shock Spallation Prediction Tool for Laser Shock Processing

Fatigue life of aerospace components is greatly enhanced by planting compressive residual stresses or favorable microstructure in the shallow surface by various processing techniques, including laser shock peening (LSP). In some situations, there are shock-induced defects in the subsurface and other area in the component; spallation can occur in severe cases, particularly in think sections. These defects are very undesirable from the standpoint of structural integrity as they defeat the purpose of using LSP in enhancing fatigue resistance. Unfortunately, existing studies and models on the nature of these defects are very limited in predicting their formation and the eventual spallation. There are strong needs to circumvent the appearance of defects in a LSP processed components. The goal of the present SBIR project is to fulfill these critical needs by developing such physics-based computational tool capable of predicting the defect formation in LSP processed components, thereby significantly reducing the efforts required to develop a new LSP applications. The centerpieces of the tool include a FDM and FEM models for dynamic stress prediction and a defect growth model that accounts for the loading history in a LSP process.