Fatigue crack growth in a laser shock peened residual stress field. (June 2019) - Pavan, M.
Highlights: Laser peening induced a fully compressive residual stress field in the specimen. Laser peened samples reported a fatigue life 4x longer than pristine components. FCGR dramatically decreased within the laser peened areas. Numerical modelling allowed to accurately predict FCGR and fatigue lives. A crack-closure mechanism is essential to correctly simulate the crack behaviour. Abstract: Laser Shock Peening is a surface treatment technique used in the aerospace sector to increase fatigue life, as well as resistance to fretting fatigue and stress corrosion cracking. In this study, laser shock peening was applied to a 6-mm-thick middle-crack tension specimen made of aluminium 2524-T351. Residual stress was measured with neutron diffraction and the contour method, along the predicted crack path prior to fatigue testing. Fatigue crack growth test results showed that fatigue life improved by a factor of 4 compared to an untreated component, owing to a significant crack growth rate reduction inside the laser peened area. A linear-elastic finite-element crack growth prediction model was also developed, obtaining predicted results in excellent agreement with the experimental data.