Novel wavelet self-optimisation threshold denoising method in axle press-fit ultrasonic defect detection
Axles are one of the most important parts of railway locomotives and vehicles. The periodic ultrasonic inspection of axles can effectively detect and monitor axle fatigue cracks. However, in the wheel-seat press-fit zone, the complex interface contact condition reduces the signal-to-noise
ratio (SNR). Therefore, the probability of false positives and false negatives increases. A novel wavelet threshold function is created to remove noise and suppress press-fit interface echoes in ultrasonic axle defect detection. Self-optimisation of the function is proposed using the positive
correlation between the correlation coefficient and SNR. The performance of the proposed method is assessed using real data and compared with traditional threshold methods and a state-of-the-art threshold. The statistic results of the amplitude and peak SNR of defect echoes show that the proposed
self-optimisation of the wavelet threshold denoising method not only maintains the amplitude of defect echoes but also provides a higher peak SNR.
Keywords: AXLE PRESS-FIT INTERFACE; SNR; ULTRASONIC DETECTION; WAVELET THRESHOLD FUNCTION
Document Type: Research Article
Publication date: 01 March 2016
- Official Journal of The British Institute of Non-Destructive Testing - includes original research and development papers, technical and scientific reviews and case studies in the fields of NDT and CM.
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