弯曲导波模态分离与频散补偿研究

Research on mode separation and dispersion compensation of flexural mode guided wave

为减少超声导波多模态和频散特性对管道缺陷检测应用时的不利影响,研究弯曲导波模态分离和导波频散补偿的方法。首先将导波信号进行时频分析,并与理论计算的时频曲线进行对比,确定信号中的各个模态,然后将各个模态信号进行频散补偿处理,最后将频散补偿后的信号相加,得到最后的结果。管道缺陷检测实验表明,由多模态和频散特性产生的多个波包可由STFT方法识别出每个波包所属的模态,经频散补偿后多个波包可对应在同一缺陷位置。实验证明导波信号经模态识别、分离和频散补偿后更利于缺陷的识别和定位,同时该方法也为弯曲导波的应用提供理论基础。

In order to reduce the adverse effects of muhi-modality and dispersion characteristics of ultrasonic guided wave signal on the detection of pipeline defects, the methods of flexural guided wave mode separation and dispersion compensation are studied. Firstly, the guide wave signal frequency analysis and theoretical calculation of frequency curve were compared to determine the signal of each modal, and then the signal of each modal was processed by dispersive compensation algorithm; Finally, the final results were obtained by adding the compensated signals. From the pipeline defect detection experiment results, it can he seen： multiple wave packets caused by multi-modal and frequency dispersion characteristics can be identified by STFT method and each wave packet can correspond to the same defect position after dispersion compensation. The experimental results show that the guided wave signal is more conducive to the identification and localization of the defects after the modal identification, separation and dispersion compensation, and the method provides a theoretical basis for the application of flexural guided wave.