Application of pulse compression in electromagnetic ultrasonic guided wave detection of aluminum sheet

被引：0
|
作者：
Shi W. [1 ,2 ]
Cheng J. [1 ]
Hu S. [1 ]
Lu C. [1 ,3 ]
Chen Y. [1 ]
机构：
[1] Key Laboratory of Nondestructive Testing, Ministry of Education, Nanchang Hangkong University, Nanchang
[2] State Key Laboratory of Acoustic Field and Acoustic Information, Academy of Acoustics, Chinese Academy of Sciences, Beijing
[3] Key Laboratory of Simulation and Numerical Modeling Technology of Jiangxi Province, Gannan Normal University, Ganzhou
来源：
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | 2022年 / 43卷 / 03期
基金：
中国国家自然科学基金;
关键词：
Aluminum alloy; Barker code; EMAT; Pulse compression; SH[!sub]0[!/sub] guided wave;
D O I：
10.7527/S1000-6893.2021.25063
中图分类号：
学科分类号：
摘要：
Aiming at the problem of poor Signal-to-Noise Ratio (SNR) of ultrasonic echoes caused by low energy conversion efficiency of Electromagnetic Ultrasonic Transducer (EMAT), the design of matching filter and sidelobe suppression filter and their implementation in electromagnetic ultrasonic detection were discussed based on phase-coded pulse compression technology.A typical two-phase coded signal, Barker code, was selected as the excitation signal.The effect of barker code signals with different lengths and carrier cycles on the pulse compression effect of guided wave EMAT detection was analyzed, and the effect of sidelobe suppression algorithm was also studied.We selected a 7075 aluminum alloy sheet with four manually prefabricated defects as the testing object, a SH0 mode guided wave EMAT was used to compare the SNRs of defect echo signals obtained by single-frequency sinusoidal signal excitation method and Barker code pulse compression technology.The results show that compared with single-frequency signal excitation, the SNR of the ultrasonic signal after Barker code pulse compression was increased by at least 7.2 dB.With Barker code pulse compression technology, a defect of small size (long×wide×deep is 10.0 mm×1.0 mm×0.25 mm) can be effectively detected, which cannot be detected with the single-frequency sinusoidal signal excitation method.With the application of Barker code pulse compression technology to guided wave EMAT detection, the increase in EMAT lift-off and the reduction in the number of synchronous averages can be realized, and requirements of online and rapid inspection can be met. © 2022, Beihang University Aerospace Knowledge Press. All right reserved.
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