为了实现对金属构件表面微小裂纹的定量检测, 本文采用仿真和实验相结合的方法, 对经过不同深度表面裂纹的激光超声透射Rayleigh(瑞利)波的波形进行对比分析, 提取畸变区域内的波形, 计算其波包能量, 研究波包能量与表面裂纹深度的依赖关系, 并通过拟合表达式对裂纹深度进行反演。研究结果表明: 当表面裂纹的深度以0.1 mm的步长从0.1 mm增加到0.5 mm时, 透射Rayleigh波的波包能量呈线性减少, 且仿真与实验分析结果相一致。反演所得裂纹深度与理论裂纹深度的最大误差为0.022 4 mm, 总体平均误差为0.011 5 mm。因此, 该研究结果可以有效的对表面裂纹深度进行定量表征。

In order to realize the quantitative detection of micro cracks on the surface of metal components, this paper adopts the method of combining simulation and experiment to carry out comparative analysis on the waveforms of laser ultrasonic transmission Rayleigh waves passing through surface cracks with different depths, extracts the waveforms in the distortion region, calculates the wave packet energy, studies the dependence of the wave packet energy on the depth of surface cracks, and inverts the crack depth through fitting expressions. The results show that when the depth of the surface crack increases from 0.1 mm to 0.5 mm in steps of 0.1 mm, the wave packet energy of the transmitted Rayleigh wave decreases linearly, and the simulation results are consistent with the experimental analysis results. The maximum error between the retrieved crack depth and the theoretical crack depth is 0.022 4 mm, and the overall average error is 0.011 5 mm. Therefore, the research results can effectively quantify the depth of surface cracks.