激光冲击“残余应力洞”的参数敏感性分析及其抑制方法

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

为研究激光冲击材料表面的"残余应力洞"现象,利用ABAQUS有限元软件,数值模拟了圆形高斯光斑的激光冲击强化。阐述了激光冲击"残余应力洞"的残余应力分布特点,讨论了不同激光冲击参数对"残余应力洞"的影响规律。提出增大光斑搭接率和利用光学透镜二元光学衍射方法形成能量均匀方光斑等2种抑制方法,并对其抑制效果进行对比分析。结果表明:冲击波峰值压力、冲击波持续时间的增加会加剧"残余应力洞",而光斑大小和冲击波上升时间的增大则效果相反;二元光学衍射方法相比增大光斑搭接率,表面残余压应力数值虽发生一定程度地降低,但残余应力场分布具有更好的均匀性,且在实际构件强化处理中具有低搭接率的工艺优势。

In order to investigate the ＂residual stress hole＂ phenomena induced by laser shock peening, we put forward a numerical simulation of laser shock peening with a round Gauss spot using ABAQUS FEM software. The residual stress distribution with ＂residual stress hole＂ was illustrated in detail. Moreover, we discussed the influences of some laser parameters on ＂residual stress hole＂, and proposed two kinds of restraining methods, namely, increasing spot overlapping-rate and using square spots with uniform energy distribution generated by the binary optical methods. The re- straining effects of the two methods were also compared and analyzed. Results indicate that the ＂residual stress hole＂ will remarkably increase with pressure amplitude and shock-wave duration, but decrease with spot size and the rise time of shock wave. Compared to increasing spot overlapping-rate, the binary optical method can generate uniform compressive residual stress. Though this uniform stress has relatively lower values, it is advantageous for its lower overlapping-rate in treating large components.