为解决激光超声技术对现代工业中零部件缺陷的快速分析、检测的问题, 本文经多次试验提取了不同缺陷深度下超声表面波信号, 并对信号进行截取、去噪、平滑等预处理; 通过HHT对预处理后反射回波信号的计算分析, 获取不同缺陷深度的反射回波的各阶IMF以及Hilbert能量谱和Hilbert边际谱, 并从中对信号的时频域特征信息进行提取分析。结果表明: 缺陷的加深使得相邻波峰波谷的最大倾斜率逐渐减小, 信号的IMF2分量的中心频率及能量随之呈增长趋势, 信号低频部分能量呈指数增长, 对总能量贡献率增大, 信号的幅频波动变得平稳, 收敛频率减小, 信号的幅频收敛性变得更好。

In order to solve the problem of rapid analysis and detection of component defects in modern industry by laser ultrasonic technology, this paper extracts the ultrasonic surface wave signals under different defect depths and tests the signals for interception, denoising and smoothing. Through the calculation and analysis of the pre-processed reflected echo signals by HHT, the IMF and Hilbert energy spectrum and Hilbert marginal spectrum of the reflected echoes with different defect depths are obtained, and the time-frequency domain characteristic information of the signals is extracted and analyzed.The results show that the deepening of the peaks of the adjacent peaks and valleys gradually decreases, and the center frequency and energy of the IMF2 component of the signal grows. The energy of the low-frequency part of the signal increases exponentially, and the contribution rate to the total energy increases.The amplitude-frequency fluctuation of the signal becomes smooth and the convergence frequency decreases. The amplitude-frequency convergence of the signal becomes better.