Enhancing the high-cycle fatigue performance of shot-peened GH4169D blades via local laser shock peening: Numerical analysis and process optimization

Impact damage induced by shot peening at the leading and trailing edges of GH4169D blades severely limits fatigue life improvement. To overcome this limitation, a hybrid surface strengthening method combining laser shock peening (LSP) at the blade edges with shot peening (SP) over the entire airfoil surface (LSP-SP) was proposed. A combined experimental and numerical investigation was performed to elucidate the effects of LSP-SP on surface integrity and fatigue behavior. The results demonstrate that the introduction of LSP at the leading and trailing edges leads to a pronounced improvement in surface integrity, as manifested by reduced surface roughness, an increased depth of the compressive residual stress layer, and enhanced microhardness. Simulation results reveal that LSP counteracts the excessively high equivalent plastic strain (PEEQ) caused by SP, thereby promoting a more uniform stress distribution and alleviating detrimental stress concentrations at the thin-walled edges. Furthermore, a multi-objective optimization framework was developed to identify the optimal LSP processing parameters. The optimized blades achieved fatigue strengths that were 17.11% and 8.82% greater than those of the milled-only blades and the conventionally SP-treated blades, respectively, confirming the effectiveness of the proposed LSP-SP approach. This study provides theoretical and methodological support for the fatigue-resistant manufacturing of thin-walled, complex-curved structures such as aero-engine blades.