基于主动Lamb波和小波变换的二维结构损伤定位研究

Damage Location of Two-Dimensional Structure Based on Wavelet Transform and Active Monitoring Technology of Lamb Wave

基于主动监测技术,将结构健康和损伤状态下的Lamb波激励响应信号进行对比,两者的差信号实际上是激励信号通过损伤折射后被接收到的类似声发射源产生的一种信号。该信号与激励响应信号比较将有时间延迟,通过Gabor小波变换确定时间延迟,从而获取损伤位置信息。实验证实这种位置信息是可靠的。

This paper presents an active monitoring method based on Lamb wave and wavelet transform to determine damage locations. The method compares damage signal with reference signal, namely undamage signal, and takes their algebraic difference as a signal caused by damage. In fact, by the analysis of Lamb wave signals recorded before and after damage, the differential signal is a reflected signal from damage which can be regarded as an acoustic emission signal. It is showed that the wavelet transform using the Gabor wavelet effectively decomposes the differential signal into its time-frequency components, and the peaks of the time-frequency distribution near the center frequency of exciting signal indicate the arrival times of waves. By calculation of time delays between the arrival of the differential and exciting signals, the damage localization points can be obtained. Experimental results for fibre glass materials prove that the damage location is reliable.