作者：蔡笑风, 刘继方, 李永峰, 赵文才

作者单位：火箭军士官学校, 山东 潍坊 262500

关键词：干耦合;Lamb波;超声检测;经验小波变换;模态分解

摘要：

为提取出干耦合Lamb波检测信号中的有用信息，采用经验小波变换（empirical wavelet transform，EWT）对检测信号进行分析。首先定义一组经验尺度和经验小波函数，根据傅里叶变换结果对信号频谱进行分割，提取出围绕中心频率具有紧支撑特性的不同频段；然后通过选择合适函数，建立紧支撑的小波框架；最后对信号进行经验小波变换，得到不同的分解模态。针对玻璃纤维复合材料板的干耦合Lamb波检测实验结果表明：采用 EWT方法能够分解出信号中不同的固有模态，揭示信号的频率结构，区分缺陷的大小，反映Lamb波传播特性。与经验模态分解（empirical mode decomposition，EMD）方法相比，EWT方法计算量小，分解模态少，没有虚假和无法解释的分量，显示该方法的优越性。

Signals analysis of Lamb wave by dry-coupled ultrasonic testing based on empirical wavelet transform
CAI Xiaofeng, LIU Jifang, LI Yongfeng, ZHAO Wencai
PLA Rocket Force NCO College, Weifang 262500, China
Abstract: In order to extract useful information in the dry-coupled Lamb wave detection signal, the empirical wavelet transform (EWT) method was used to analyze the detection signal. Firstly, a set of empirical scales and empirical wavelet functions were defined. According to the results of Fourier transform, the spectrum of the signal was segmented, and different frequency bands with tightly-supported characteristics around the center frequency were extracted. Then a tightly supported wavelet frame was established by selecting an appropriate function. Finally, the signal was subjected to empirical wavelet transform to obtain different decomposition modes. The experimental results of dry-coupled Lamb wave detection for glass fiber composite panels showed that the EWT method can be used to decompose different intrinsic modes in the signal, which reveal the frequency structure and the size of the defect, and reflect the propagation characteristics of Lamb wave. Compared with the EMD method, the EWT method has little computation, less decomposition modes, and no false and unexplained components, which shows the superiority of the method.
Keywords: dry-coupled;Lamb wave;ultrasonic test;empirical wavelet transform;mode decomposition
2019, 45(1):139-144  收稿日期: 2018-02-10;收到修改稿日期: 2018-04-19
基金项目: 国家自然科学基金资助项目（51275517）
作者简介: 蔡笑风(1985-),男,湖北浠水县人,讲师,博士,研究方向为动力系统无损检测
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