基于小波包能量变化率的激光超声处理

Laser ultrasonic treatment based on wavelet packet energy change rate

为提供解决航空发动机原位裂纹的快速检测方法,得到缺陷深度与特征量之间的关系,使用激光器在一系列不同缺陷深度的航空板上激发声表面波,对收集到的信号进行预处理,并提出新的小波包变换能量变化率指标,用于进行缺陷损伤识别。结果表明:反射波信号在S_(80)、S_(81)频带上的小波包能量变化率随缺陷深度的增加呈现增加趋势,增长幅度分别为96.8%、86.3%;而反射回波在S_(80)、S_(83)频带上的小波包能量变化率较为显著,增长幅度分别为23.8%、80.2%。该分析方法为激光超声表征表面缺陷提供新的思路,为今后从能量变化率指标分析裂纹深度奠定基础。

In order to provide a quick detection method for situ crack of aeroengine so as to get the relationship between detect depth and feature quantity, lasers are used on aviation plate with different defect depths to motivate surface acoustic wave, and carry out pre -treatment for collected signals, and provide a new wavelet packet transformation energy change rate index, which is used for defect damage identification. The results show that the change rate of wavelet packet energy of reflected wave signal in the S80 and S81 bands increases along with the defect depth with increasing rate respectively being 96.8% and 86.3%; while the change rate of wavelet packet energy of reflected wave in S80 and S83 bands is significant, with increasing rate respectively being 23.8% and 80.2%. The method provides a new idea for laser ultrasonic surface characteristic defects, which lays a solid foundation for analyzing the crack depth based on energy change rate index in the future.