The effects of laser shock peening scanning patterns on residual stress distribution and fatigue life of AA2024 aluminium alloy

Abstract

Laser shock peening (LSP) utilizes the action of laser induced plasma to cause plastic deformation in metallic components. As a result, compressive residual stress is induced on the surface to improve its fatigue life. Our contribution in this paper is to investigate the effects of LSP scanning patterns on residual stress distribution and fatigue performance in Al 2024-T351 specimens. We use a 3D finite element analysis to simulate the residual stress distribution and experiment to establish correlation between the residual stress distribution and fatigue performance. We employ X-Y scanning pattern, Y-X scanning pattern and L-Spiral scanning pattern as the advancing scanning methods in LSP dog-bone specimens. Our results show that, tensile residual stresses are sandwiched between two compressive residual stresses at the front and back surfaces of the specimen. We therefore, observe some variations in residual stress distribution at the laser affected zone. In which case, the L-Spiral scanning pattern produces favorable residual stress distribution and considers as relatively more efficient to extend fatigue performance. We further observe that the extended fatigue life of 287% at 103 MPa shows that the LSP advancing scanning pattern has a great impact on residual stress and fatigue life respectively.