Mechanism influence on fatigue characters of aerial engine blade by laser shock processing

Abstract

During Laser Shock Processing when a material is irradiated with short laser pulses (ns) of very high densities (>GW/cm²), a high intensity shock wave is generated. This treatment can reduce the rate of fatigue cracking and stress corrosion cracking in structural metals or alloys needed for aerospace, nuclear power plants, and military applications. Laser shock processing has been shown to be a viable method of strengthen metallic components. When laser pulse width is 20ns, laser energy is 35J, the effect of LSP on alloy surface residual stresses and stress intensity factor were analyzed. And the influence of the surface residual stress on material fatigue life after LSP was discussed from the theory of the fracture mechanics. Transformation on the characters of aerial engine blade by laser shock processing and influence on the fatigue life with these transformations were studied. And the relatively fatigue life experiment of aerial engine blade was done to validate the influence on the fatigue life of aerial engine by laser shock processing. It was found that laser shock processing could bring residual compressive stress and high-density dislocation on the surface of the blade. All these transformation greatly increase the fatigue life of aerial engine blade.