非金属防腐层分层缺陷超声导波检测

摘要

As nonmetallic coating is commonly used on the surface of industrial materials,it is of great importance to ensure that the coating is intact for normal operation of materials.Aiming at detecting the delamination damage of nonmetallic coating on metallic base material,a delamination damage detection method based on wavelet energy is proposed in this paper.Firstly,the propagation model of guided wave in double-layer tubular medium is established and a detection method based on wavelet energy is proposed.Secondly,specimens are made and an experiment platform is built up.Ultimately,the delamination damages are studied and compared using gain value and wavelet energy.Results show that generally,the gain value of the same echo amplitude decreases as the delamination damage grows.However,small damages could not be detected using this method,while the wavelet energy of the detected signals can detect the delamination damage more effectively.Especially when the damage is small,wavelet energy method can meet the requirement of detecting the delamination damages.The delamination damage detection method based on wavelet energy can provide a reference for the future studies in the testing of complicated multi-layer materials.%工业用材料表面通常覆盖有非金属防腐层,保证防腐层的完好对实现材料的正常工作具有重要意义.为实现对非金属防腐涂层的分层缺陷检测,该文提出基于小波能量值的分层缺陷损伤评估方法.首先建立超声导波在双层板状介质中的传播模型,提出基于小波能量值的检测理论,制作试样并建立实验平台,分别利用增益值和小波能量值对分层缺陷进行检测比较.实验结果表明随着分层缺陷宽度的增加,达到相同回波幅度的增益值逐渐下降,但增益值方法在较小范围内无法识别出分层缺陷;而接收信号的小波能量值能更好地实现对分层缺陷的检测,特别是在缺陷宽度较低的情况下,采用小波能量法能较好满足分层缺陷的检测需求.基于小波能量值的分层缺陷检测方法可为后续对复杂多层材料检测提供参考.