Numerical simulation of laser shock peening in presence of weld for fatigue life design

Laser shock peening (LSP) is a surface mitigation technique that can be applied to improve the life of a metallic component through the generation of a compressive surface stress field induced by high-power laser pulses. Numerical simulation of LSP (produced residual stresses) in presence of an initial stress field similar to those obtained under welding has been carried out in nonlinear dynamic by coupling an explicit code (Europlexus) and an implicit one (Code Aster). In the first step, an axisymetrical model has been validated by comparison with an analytical solution considering an elastic-perfectly plastic behavior law. Then, comparisons with Abaqus calculations have been carried out in terms of displacements and residual stresses using the JohnsonCook high strain rate constitutive law to validate multi-impact 3D modeling. High strain rate parameter of Johnson-Cook law has been identified using LSP on thin plates. Validations of the simulations are then performed by comparing with experimental determined deformations caused by LSP on thick plates. For 25 overlapped shots, LSP induced residual stresses calculated with and without initial residual stresses similar to those obtain under welding have been compared to adress the effect of initial stresses on final residual fields.