基于匹配追踪的L模态超声导波检测复合绝缘子芯棒缺陷研究

Study on L Modal Guided Wave Detecting Defect of Composite Insulators Core Rod Based on Matching Pursuit

传统的复合绝缘子缺陷检测方法主要集中在芯棒外部结构的缺陷上,并不能有效发现芯棒本身中的缺陷,为此提出了一种针对芯棒本身缺陷且能定量估计缺陷大小的检测方法:基于匹配追踪的L模态超声导波检测。通过建立芯棒模型分析了L模态超声导波在芯棒中的传播特性,确定了导波检测的频率范围。基于理论分析,以10周期40 k Hz的导波为激励信号,选取芯棒缺陷轴向长度为8 mm和2 mm,进行了有限元仿真和实验。仿真和实验结果表明:L模态超声导波能准确地检测出复合绝缘子芯棒中的缺陷,且通过Gabor原子构建波形字典,运用匹配追踪算法估计出芯棒缺陷轴向长度的相对误差分别为5. 4%和16. 35%。理论分析、有限元仿真和实验一起验证了该方法的可行性、有效性,为复合绝缘子芯棒缺陷的检测和定量分析提供了一种新的思路。

Traditional composite insulators defect detection methods were mainly concentrated in the external structure defects of composite insulators rod,and the defects in rod could not be found effectively,so a new method with ability to estimate defect sizes was presented:L modal guided wave detection based on matching pursuit.Theory of guided wave propagating in composite insulators rod was analyzed,relevant dispersion curve of phase velocity and group velocity were obtained.Also,the range of frequency for guided wave detection was determined.Finite element simulation and experiment were carried out with excitation guided wave with 10 cycles at 40 kHz and axial defects in 8 mm and 2 mm according to theory analysis,which showed that L modal guided wave could detect defect of composite insulators rod accurately.In the meanwhile,matching pursuit algorithm was used on the basis of waveform dictionary constructed by Gabor atoms,which showed that the relative erros of axial defect estimated by matching pursuit algorithm is 5.4%and 16.35%respectively.Based on thory analysis,finite element simulation and experimrnt,it is advisable and effective to detect defect of composite insulators rod and estimate the specific defect size with L modal guided wave based on matching pursuit.