中文摘要：

为研究激光冲击7050铝合金薄板试样形成残余应力洞的机制，分别使用功率密度为1．98GW／cm2和2．77GW／cm2的激光冲击7050铝合金试样。采用ANsYS／LS-DYNA有限元分析软件模拟分析了在功率密度为1．98GW／cm。的激光束冲击下的薄板试样。实验中利用X射线应力分析仪测量薄板试样和厚板试样的残余应力分布，利用压电薄膜传感器测量激光冲击时试样的动态应变，并利用三维显微系统观察激光冲击区域的表面微结构。实验结果表明，功率密度为1．98GW／cm2和2．77GW／cm2的激光束冲击7050铝合金薄板试样后均产生了残余应力洞现象。反射边界条件下的模拟结果与实验数据具有较好的一致性，表明稀疏波在光斑中心的会聚是产生残余应力洞现象的主要原因。由残余应力分布和动态应变可知，在试样内来回反射的冲击波对残余应力洞的影响不容忽视；功率密度为2．77GW／cm2的激光束冲击加载后，薄板、厚板试样冲击区域中心的厚度分别比临近区域的厚度大10．800μm和8．150μm；在表面稀疏波与冲击波的共同作用下，试样表面均产生了残余应力洞现象。

英文摘要：

To investigate the formation mechanism of residual stress holes on 7050 aluminum alloy sheet sample under laser shock, the 7050 aluminum alloy samples are shocked by laser with the power densities of 1.98 GW/cm2 and 2.77 GW/cm2 , respectively. The finite element analysis software ANSYS/LS-DYNA is applied to simulating the sheet samples shocked by the laser with the power density of 1.98 GW/cm2 . The distributions of residual stress on the thin plate and thick plate samples are analyzed by the X-ray stress analyzer, the dynamic strain of the samples shocked by laser is measured with the piezoelectric thin film sensor, and the surface microstructures on the shocked areas are observed through a three-dimensional microscopy system. The experimental results show that the residual stress holes on the 7050 aluminum alloy sheet samples can be caused by the laser shock with the power densities of 1.98 GW/cm2 and 2.77 GW/cm2 . Under reflecting boundary conditions, the simulation results agree well with the experimental data, which indicates that the gathering of the rarefaction waves to the center of the light spot is the major reason for occurrence of the residual stress holes. Through analyzing the distribution of residual stress and dynamic strain, the influence of the shock waves reflected back and forth in the samples on the residual stress holes cannot he ignored. The thicknesses of the central areas of the thin and thick plate samples are 10. 800μm and 8. 150 μm thicker than those of their surrounding areas respectively after the samples are shocked by laser with power density of 2.77 GW/cm2. The residual stress holes on sample surfaces are caused by the joint effect of rarefaction waves and laser shock waves.