CAJ | 학술논문

脉冲涡流探伤时，瞬态信号和一次扫描波形中的噪声干扰成分会影响缺陷定量检测的准确度。对于该问题，研究了小波分析在脉冲涡流探伤中的两方面应用。对于瞬态信号，利用小波阈值去噪法对其处理，分析了阈值方法的不同对去噪效果的影响并进行实验验证，并与传统低通滤波进行了比较；对于一次扫描波形，利用小波分解后的近似系数重构信号，再提取峰值扫描曲线。实验结果证明：在瞬态信号的去噪中，软阈值法相比于硬阈值法有更好的去噪效果，其可以在保留真实信号特征的情况下去除噪声，并解决了传统低通滤波会损害真实信号特征的问题，还原了信号的真实峰值和过零时间；使用该方法获得的峰值扫描曲线消去了抖动，极值点时间变得明确，提高了缺陷长度的检测准确度。
맥충와류탐상시，순태신호화일차소묘파형중적조성간우성분회영향결함정량검측적준학도。대우해문제，연구료소파분석재맥충와류탐상중적량방면응용。대우순태신호，이용소파역치거조법대기처리，분석료역치방법적불동대거조효과적영향병진행실험험증，병여전통저통려파진행료비교；대우일차소묘파형，이용소파분해후적근사계수중구신호，재제취봉치소묘곡선。실험결과증명：재순태신호적거조중，연역치법상비우경역치법유경호적거조효과，기가이재보류진실신호특정적정황하거제조성，병해결료전통저통려파회손해진실신호특정적문제，환원료신호적진실봉치화과령시간；사용해방법획득적봉치소묘곡선소거료두동，겁치점시간변득명학，제고료결함장도적검측준학도。
During pulsed eddy current testing, the noise component of the transient signal and one-time scan waveforms can affect the accuracy of quantitative detection of defects. Both the transient and one-time scan waveforms of pulsed eddy signal are analyzed. Wavelet analysis is utilized in pulsed eddy testing. Wavelet threshold denoise is used to process tran-sient pulsed eddy signal and the denoise performances under different threshold denoise methods are compared and ana-lyzed theoretically. Experimental results confirm the efficiency of wavelet threshold denoise method by comparing with traditional low-pass filters. For one-time scan waveforms, the approximate coefficients of wavelet decomposition are used to reconstruct original signal and peak scanning curves are extracted from reconstructed signal. The experimental results show that, soft threshold has better performance than hard threshold in transient signal denoise because soft threshold not only retains real signal characteristics but also restores the peak value and zero time of the real signal. Therefore soft threshold solves the problem in traditional filter. The peak value scanning curve acquired in this paper eliminates shaking and the extremum points become explicit which improve the defects length testing precision.