小波变换用于钢丝绳断丝检测的研究

Application of Wavelet Transform to Study on Measurement of the Broken Silk for Steel Cable

本文采用漏磁场探伤方法对钢丝绳断丝进行检测,该方法的原理是利用励磁磁场和缺陷(即钢丝断丝处)相互作用产生的漏磁场来检测钢丝绳断丝,并且利用霍尔元件能够准确地获取漏磁场信号.首次把声表面波式小波变换的重构器件应用于钢丝绳断丝检测中.发现声表面波器件的发射叉指换能器和接收叉指换能器的指条重叠包络均按照小波函数(如Morlet小波)包络设计时,从而得到声表面波器件的发射叉指换能器和接收叉指换能器的脉冲响应函数均等于小波函数,所以制作出了声表面波式小波变换的重构器件.该器件是一带通滤波器,其相对带宽是1.1%,所以该器件可有效滤除干扰信号.

The method that the leak magnetic field detects a flaw is adopted to measure the broken silks of steel cable, and the principle of the method is to use that action between the excitation magnetic field and the flaw （i. e. the broken silk place） produces the leak magnetic field that is used to measure the broken silks of steel cable, and Hall element is used to accurately take the signal of the leak magnetic field. Surface-acoustic-wave type of the reconstruction element for wavelet transform is firstly applied to the measurement of the broken silks for steel cable. That the pulse-response envelope of the transmitting interdigital transducer （IDT） and the receiving IDT for surface acoustic wave （SAW） element is designed according to a wavelet function （such as Morlet wavelet） is discovered, thus it is equal to a wavelet function. Therefore, SAW type of the reconstruction element for wavelet transform is manufactured. The element is a band filter, and its relative band width is 1.1%, so it can effectively filter the jamming signal.