Geometry distortion and residual stress of alternate double-sided laser peening of thin section component

Laser peening of components with thin section is of great concern in industry to improve anti-fatigue properties. This study proposes alternate double-sided laser peening (ADLP) as an optional way for the surface treatment of thin section component to overcome the risk of internal spallation and facility cost in simultaneous double-sided laser peening (SDLP). Experiments are conducted on the special-designed samples with thin section to investigate the distortion behavior and residual stress under laser peening of both sides sequentially. Numerical model are developed to analyze the generation and recover of geometry distortion for ADLP process. The results shows that the geometry distortion after single-sided laser peening is observed to be sensitive to laser pulse energy to generate different profile directions. The feasibility of ADSP is proved for the treatment of thin section with distortion control because the second laser peening on the other side of thin section can eliminate the distortion. The generation of different distortion behaviors is found to be closely related to the plastic strain field generated by the transmission of shock-induced stress wave across the thickness section. The numerical simulation shows that a symmetric tensile plastic strain field in plane section is generated across the thickness section for each laser pulse energy after completing laser peening on both sides. Furthermore, both experiments and model prediction propose that compressive residual stress is induced on both sides of thin section by ADLP process, which ensures the ADLP process effective for the treatment of thin section.