薄壁管道内部径向裂纹的检测

DETECTION OF THE RADIAL CRACK IN A THIN-WALLED TUBE

根据含内部径向裂纹圆环中周向导波的信息 ,采用Gabor连续小波变换进行分析 ,提取出任一点动态应变中某一频率分量上的信息。通过对回波信号的深入研究 ,可以由该测点的小波分析结果定量地检测出圆环内部径向裂纹的位置 ,并可以进一步判断损伤程度。文中提出的方法便于实际应用 ,有利于推广到工程实际薄壁管道构件内部损伤的检测。

A continuous wavelet transform is applied to analyzing circumferential guided waves in an annulus with an interior radial crack. For circumferential guided waves signals inspired by an impact load, continuous wavelet transform based on Gabor wavelet can effectively solve the frequency dispersion problem in wave propagating process, and the arrival times and amplitudes of each frequency can be extracted from dynamic strain signals at an arbitrary point on the surface of the annulus. A thin-wall annulus with inner-to-outer radius ratio 0.95 is discussed by this method, and it can be considered separately by the different model with different crack depth. Because the first and second modes waves are propagating at all frequency-domain, they can be extracted by a suitable wavelet scaling parameter. After considering the interaction on crack and the mode conversion of these two modes waves, the location of the interior radial crack in the annulus can be identified quantificationally by the wavelet result of the echo signals. Then, the extent of damage can also be estimated by analyzing the reflected wave from crack surface. This method is a powerful tool to detect the interior damage in thin-walled tubes, and it is convenient to extend to practical engineering applications.