含缺陷管道超声导波检测信号的相关性分析

Signal correlation analysis of ultrasonic guided wave in damaged pipe

提出一种基于相关性分析的管道缺陷检测方法.该方法通过截取入射信号作为主动检测信号,将实测信号作为被检测信号.借助于合适的窗函数计算检测信号和不同时刻测试信号的相关系数,通过相关系数的峰值点判断波到时刻,从而提高识别精度.为了消除来源于模式转换和噪声的杂波信号,设置阈值可达到滤波效果.利用该方法,对单位置腐蚀和双位置腐蚀,在不同噪声水平下的测试信号进行相关性分析.结果表明,阈值法可以较好地抑制噪声和模式转换对识别结果的影响,且具有较高的识别精度.该方法原理简单,操作简便,可用于管道腐蚀检测的在线检测.

In this paper, it is suggested that the scheme of corrosion detection in a pipe based on correlation coefficients. In this scheme, the incident signal is defined as the active detected signal （ADS）, while the measurements signal is treated as the passive detection signal （PDS）. The correlation coefficients between ADS and PDS at different time are calculated with the help of a window function, from which the arriving time of the echo by the damage could be determined. A suitable threshold is proposed to reduce the influence of the noise. Simulation shows that the scheme is good for damage detection on- line for locating one or two flaws in a pipe.