激光冲击“残余应力洞”的参数影响

Sensitivity Analysis of“Residual Stress Hole”Induced by Laser Shock Peening

在激光冲击强化过程中,光斑边界处会产生表面稀疏波,并向光斑中心传播、汇聚,使中心区域材料发生反向塑性变形,造成光斑中心区域残余压应力缺失,从而形成材料表面"残余应力洞"现象。利用ABAQUS有限元软件进行了圆形高斯光斑的激光冲击强化数值模拟,讨论了不同材料和模型尺寸、激光冲击参数等因素对"残余应力洞"的影响规律。结果表明,随着冲击波峰值压力、冲击波作用时间、冲击次数的增加,"残余应力洞"现象随之加剧;而随着材料动态弹性极限、光斑大小、冲击波上升时间、光斑搭接率的增加,"残余应力洞"现象则会随之减弱。该研究可为后期激光冲击强化光斑光学整形技术的应用,以及基于残余应力场优化的工艺设计提供依据。

During the process of laser shock peening,rarefactional wave is generated in spot boundary,propagates to the spot center,and converges in the spot center. Under the converging of rarefactional wave,reverse plastic deformation is formed after the action of laser shock waves. Compressive residual stress reducing results in the phenomena of “residual stress hole”occurring. Numerical simulation of laser shock peening with one round gauss spot is carried out by ABAQUS FEM software. The influence rule of “residual stress hole”phenomena with different parameters is discussed,for instance material type,model size and laser parameters. Results indicate that the severity of “residual stress hole”varies with parameter. The severity degree increases with the parameters of shock-wave amplitude pressure,shock-wave duration and LSP impacts. Thus it decreases with the parameters of material dynamic elastic limit,laser-spot size and shock-wave rise-time. This study will be useful for the application of laser spot optical shaping,and valuable for the technics design based on the optimization of residual stress field.