为了研究激光冲击所引起的瑞利表面波在材料表面裂纹检测方面的作用, 采用ABAQUS建立了激光超声无损检测表面裂纹的模型,并模拟激光在材料表面激发瑞利波及瑞利波沿材料表面传播的过程。从激光的峰值压力、空间分布、时间分布3个方面将激光冲击作用等效成力的作用, 体现了激光参量在作用过程中所起到的作用; 同时, 使用无限单元消除了边界的反射回波。通过对接收点处瑞利表面波信号的分析, 进行了不同深度表面裂纹对瑞利波回波峰值影响的定量比较。结果表明, 瑞利反射波的正向峰值与下一次最大正向位移所对应的时间的比值和表面裂纹深度之间存在着线性关系, 进而为实验测量表面裂纹深度提供了一种测量方法。

To research the effect of Rayleigh surface wave induced by laser shock on the surface crack detection of materials, an equivalent model of laser ultrasonic nondestructive testing was established by using ABAQUS. The process of Rayleigh wave aroused by laser shocking and the propagating process of Rayleigh wave on the surface were simulated. Considering laser parameters, laser shock was equivalent to force impact according to peak pressure, spatial distribution and time distribution. Infinite elements were used to eliminate echo waves. By analyzing the Rayleigh surface wave signal on the receiver point, the effect of surface crack depth on Rayleigh wave echo peak was compared quantitatively. The result shows that, linear relationship exists between the rate of the positive peak value of Rayleigh wave and the time of the next maximum forward displacement and surface crack depth. The results provide a method for experimental measuring on the surface crack.