Crystal plasticity modeling of uniaxial tensile and fatigue failure behaviors of laser shock peened aluminum alloy

Laser Shock Peening (LSP) has emerged as an advanced surface treatment technique for improving the mechanical properties and fatigue resistance of metallic materials, particularly in 7075 aluminum alloy. This study investigates the effects of LSP on the mechanical behaviors of 7075-T7351 aluminum alloy through microstructural characterization, uniaxial tensile tests, fatigue tests, and Crystal Plasticity Finite Element Modeling (CPFEM). Results indicate that LSP introduces a maximum residual compressive stress of 193 MPa and a dislocation density of 5.88 × 10¹⁵ m^-2 at the sample surface. LSP enhances the ultimate strength (from 470 MPa to 480 MPa), together with significant improvements in fatigue limit (from 150 MPa to 160 MPa) and fatigue life. A dislocation-based crystal plasticity model incorporating multiple deformation mechanisms has been developed, which quantitatively captures the material's tensile and cyclic deformation behavior. Moreover, the integration of CPFEM with the fatigue indicator parameters method enables accurate prediction of high-cycle fatigue life in aluminum alloys. These findings offer mechanistic insights into the role of residual stress and gradient microstructure in fatigue enhancement, which may inform future optimization of LSP treatment strategies for aluminum alloys.