关键词: 超声导波, 钢绞线, 降噪, 缺陷, 小波分析

Abstract: In the inspection test on steel strands by using ultrasonic guided waves, the lowest longitudinal mode, L(0,1) mode, is excited and received by a pair of developed magnetostrictive sensors in a seven-wire, 17.80 mm nominal diameter steel strands. Then, the signal is denoised by using the method of multi-level discrete wavelet decomposition and single branch reconstruction. The daubechies wavelet of order 40 is used as the mother wavelet for the decomposition. This wavelet denoise method improves the signal-to-noise ratio. Furthermore, a steel strands with 3.00 mm depth notch on peripheral wire is inspected, the information of the defect is extracted from the signal by using the wavelet denoise. This signal processing method of wavelet denoise provide foundation for application of ultrasonic guided waves technique to health monitoring of steel strands.

Key words: Defect, Denoise, Steel strands, Ultrasonic guided waves, Wavelet analysis