Numerrical Simulation On Residual Stress And Fatigue Crack Growth By Laser Shot Peening

Laser shot peening(LSP) induced residual stress field could restrain the process of crack initiation and growth,which can achieve better anti-fatigue property of material. With the FEA method,the residual stress field induced by LSP,as well as the fatigue crack growth under various process parameters was preliminarily investigated.The principal works are as follows:The influence of surface integrality changes after LSP on fatigue crack initiation and growth was analyzed first and then the fatigue crack growth under residual stress field was theoretical investigated.Based on the FEA code ABAQUS and MSC.Fatigue, a fatigue analysis procedure was set up to study fatigue crack growth with residual stress field,which provide an effective method to the evaluation of anti-fatigue property after LSP.Through the FEA code ABAQUS,the model of the process of LSP was created to simulate the dynamic progress of strain and stress.The mechanic effect of metal material under high value shock wave loading and the residual stress distribution of were discussed.Using a center hole fatigue specimen,the residual stress field under various LSP process parameters was studied,which provide stress distribution for following analysis of fatigue crack growth.Using the MSC.Fatigue fatigue crack analysis module based on fracture mechanics,the fatigue crack propagation after LSP was investigated,and the reason of how LSP improve the anti-fatigue property of material was researched.With the Taguchi method,fatigue crack growth under various process parameters and the correspondence of the key parameters to fatigue crack growth life was simulated,and signification level of some key process parameters to fatigue crack growth life was obtained by SNR analysis and variance analysis,then optimal influence factor level was found out.After analyzing the influence level of various process parameters,the LSP induced residual stress under different process parameters and its effect to fatigue crack growth was evaluated,which provided an tentative method for predicting fatigue crack growth property after LSP and have guideline for subsequent fatigue experiments.LSP experiments were carried out on 6061-T6 aluminum alloy,the residual stress and surface morphology were in accord with the results of the FEA method,and it proved the validity of the finite element analysis model of LSP.