Research on the electromagnetic ultrasonic surface wave detection method of rail tread crack based on synchrosqueezed wavelet transform and pulse compression
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TH878 TB552

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    Abstract:

    Fatigue cracks on the rail tread seriously affect the safety of trains. To address the problem that detects rail tread cracks quickly and effectively, a method for rapid detection of rail tread cracks is proposed in this article. Firstly, the mathematical models with Gaussian white noise and sinusoidal signal plus Gaussian white noise interference are formulated respectively. The noise suppression effectiveness of three signal processing methods are analyzed, including the coded pulse compression, the synchrosqueezed wavelet transform and the pulse compression after synchrosqueezed wavelet transform method. Secondly, to evaluate the noise suppression ability of the above methods, the surface wave electromagnetic ultrasonic transducer with excitation frequency of 1 MHz is used to detect the rail tread with cracks. Finally, the ultrasonic echo of the detected crack is taken as the research object. The noise reduction ability and ultrasonic imaging effect of the Hilbert Huang method for processing the ultrasonic echo signal corresponding to a single frequency pulse and the method of synchrosqueezed wavelet transform followed by pulse compression are compared. Results show that the proposed method can obtain the location and number of cracks on the rail tread. When Hilbert Huang transform is used to process the original ultrasonic echo with no synchronous average, the signal-to-noise ratio of the echo is low, which causes the failure of the empirical mode decomposition ( EMD). Under the condition that Barker code is used as the excitation signal and there is no synchronous average acquisition, the signal-to-noise ratio of ultrasonic echo obtained by using the pulse compression after synchrosqueezed wavelet transform method is 6. 82 dB higher than that using only phase coding pulse compression. It is 11. 02 dB higher than that using only synchrosqueezed wavelet transform, which can significantly improve the detection speed and B-scan image definition.

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  • Received:
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  • Online: June 30,2023
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