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激光冲击后在其金属表面形成一定形式的残余压应力,可对材料表面进行改性处理。采用ABAQUS有限元软件,研究激光功率密度、光斑形状对板料表层残余应力场分布的影响,探索残余应力场机制。结果表明,提高激光功率密度可以增加板料表层残余应力场,但随功率密度增大会产生“残余应力洞”现象;激光冲击后材料位移和表面应力动态响应分析表明,材料表面受冲击与材料弹性力作用产生振荡过程,冲击光斑边缘产生反射波(稀疏波)的反向加载,引起反向塑性变形,形成“残余应力洞”现象;光斑形状影响稀疏波向中心汇聚,造成中心残余压应力不同的缺失。该研究为工艺参数优化,减少冲击中心残余应力缺乏,获得更好的激光冲击处理强化效果提供依据。
After laser shock, a certain form of residual compressive stress is formed on the metal surface, and the surface of the material can be modified. ABAQUS finite element software was used to study the influence of laser power density and spot shape on the residual stress field distribution on the sheet metal surface and to explore the mechanism of residual stress field. The results show that increasing the laser power density can increase the surface residual stress field, but the phenomenon of “residual stress hole ” occurs with the increase of the power density. The analysis of the material displacement and the surface stress dynamic response after laser shock shows that the surface of the material is affected by the impact and The elastic force of the material causes the oscillation process, and the reverse loading of the reflected wave (the sparse wave) occurs at the edge of the impact spot, causing the reverse plastic deformation and the phenomenon of “residual stress hole”. The spot shape affects the convergence of the sparse wave to the center, Residual compressive stress different absent. The research provided the basis for optimizing the process parameters, reducing the residual stress in the impact center and obtaining better laser shock treatment strengthening effect.