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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 rapid detection of aeroengine in-situ crack and obtain the relationship between the characteristic information and the depth of defect, this paper uses a laser to stimulate laser ultrasonic signals on a series of aviation aluminum plates with different depth defects through the experimental platform that the laboratory has set up, The collected signals are denoised by wavelet, and the band energy distribution characteristics of denoised reflected echo signals are studied by wavelet packet. The results show that the energy of the reflected echo signal mainly concentrates on the band S80 ~ S87. When the defect depth is 0.2 mm to 0.4 mm, the energy mainly concentrates on two adjacent bands. When the defect depth is 0.5 mm to 0.7 mm , The energy is mainly concentrated in the two frequency bands. This method provides a way for quantitative characterization of surface microdefects by ultrasonic signals and lays a foundation for the analysis of crack depth in terms of frequency band energy in the future.