激光超声的小波包能量分析

Wavelet packet energy analysis of laser ultrasonic

为了解决航空发动机原位裂纹的快速检测问题,得到特征信息与缺陷深度之间的关系,本文通过实验室已搭建的实验平台,使用激光器在一系列不同深度缺陷的航空铝板上激发激光超声信号,对收集到的信号进行小波去噪,通过小波包研究去噪后的反射回波信号的频带能量分布特征。结果表明:反射回波信号的能量主要集中于S80~S87频带;当缺陷深度为0.2 mm至0.4 mm时,能量主要集中在相邻的两个频带上;当缺陷深度为0.5 mm至0.7 mm时,能量主要集中在相间的两个频带上。该分析方法为超声信号定量表征表面微缺陷提供了一种思路,为今后从频带能量方面分析裂纹深度奠定了一定的基础。

In order to solve the problem of the rapid detection of aircraft engine in situ cracks, and get the relationship between feature information and detect depth, the laboratory experimental platform is built, laser is used to excite laser ultrasonic signals on a range of aviation aluminum plates with different depth defects, the collected signal is proposed by wavelet de-noising, and the band energy distribution of the reflected echo signal is studied by using wavelet packet. The results show that the energy of reflected echo signal is mainly concentrated in the S80~S87 band. When the depth of defect is 0.2 mm to 0.4 mm, the energy is mainly concentrated in the adjacent bands. When the depth of defect is 0.5 mm to 0.7 mm, the energy is mainly concentrated in the two bands. This method provides a way to quantify surface micro-defects by ultrasonic signals, which will lay a foundation for the future analysis of crack depth from band energy.