On the prediction of fatigue crack growth based on weight functions in residual stress fields induced by laser shock peening and laser heating

Abstract

This study deals with fatigue crack growth prediction for thin sheet AA2024 specimens with residual stresses introduced through laser shock peening and laser heating treatments. Different weight functions are used to calculate the stress intensity factor due to the presence of residual stresses. A superposition principle is used by calculating the total stress intensity factor considering the applied loads and residual stresses. The fatigue crack growth is predicted using the Paris' law based on the effective stress intensity factor range, in that the effect of residual stresses is considered by changing the total stress intensity factor ratio. It is concluded, that weight functions are a powerful tool to predict fatigue crack growth in AA2024 containing residual stress fields, as long as the gradient in the loading direction, as induced by laser shock peening and laser heating, is moderate.

Temperature evolution at fatigue crack tip area after laser shock peening

“…The creation of new structural materials and their operation under various conditions require the development of existing and the creation of new methods for predicting the durability and strength of structures. At present time, a laser shock peening (LSP) technique for hardening metals and alloys is being actively developed [1]. During LSP an elasticplastic wave changes surface layer and creates the compress residual stress that make it possible to use this phenomena for increase life time of materials and engineering construction.…”