
Proceedings Paper
Application of wavelet analysis in laser-generated ultrasonic nondestructive testingFormat | Member Price | Non-Member Price |
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Paper Abstract
Laser-generated ultrasonic technology possesses incomparable advantages to many conventional testing methods of
complete non-contact, fast response, non-destruction, wide band range, high precision and low cost, which is widely
used to test the defects of aerocraft’s components. However, the actual laser ultrasound signal is often mixed with a
variety of noise and interference, which brings certain difficulty to material characterization and flaw identification. In
order to de-noise laser-generated ultrasonic signal and enhance the detection sensitivity and reliability, wavelet analysis
is applied to signal processing in this paper. The paper discusses the wavelet threshold de-noising methods, and the
features of two traditional wavelet shrinkage methods----soft threshold and hard threshold, are analyzed in wavelet
domain. Then an improved wavelet threshold function method is proposed on the basis of the two traditional threshold
methods. According to the characteristics of the signal, db6 wavelet and 4 levels’ decomposition are selected to complete
the signal analysis. The functions of soft threshold, hard threshold and the improved threshold are employed in wavelet
coefficients threshold processing respectively. Based on the analysis and comparison of each denoised figure and
statistical property, the improved method can get a remarkable effect in signal de-noising is proved. It is concluded by
theory analyzing and experiment research that the improved wavelet threshold function method has more advantages in
laser ultrasonic signal de-noising compared with the two traditional threshold methods, which not only overcomes the
shortcoming of discontinuity of hard threshold method, but also decreases the fixed bias between estimated wavelet
coefficients and decomposed wavelet coefficients of soft threshold method.
Paper Details
Date Published: 15 November 2011
PDF: 8 pages
Proc. SPIE 8321, Seventh International Symposium on Precision Engineering Measurements and Instrumentation, 832116 (15 November 2011); doi: 10.1117/12.903987
Published in SPIE Proceedings Vol. 8321:
Seventh International Symposium on Precision Engineering Measurements and Instrumentation
Kuang-Chao Fan; Man Song; Rong-Sheng Lu, Editor(s)
PDF: 8 pages
Proc. SPIE 8321, Seventh International Symposium on Precision Engineering Measurements and Instrumentation, 832116 (15 November 2011); doi: 10.1117/12.903987
Show Author Affiliations
Xianglin Tan, National Univ. of Defense Technology (China)
Mengchun Pan, National Univ. of Defense Technology (China)
Mengchun Pan, National Univ. of Defense Technology (China)
Shitu Luo, National Univ. of Defense Technology (China)
Chengguang Fan, National Univ. of Defense Technology (China)
Chengguang Fan, National Univ. of Defense Technology (China)
Published in SPIE Proceedings Vol. 8321:
Seventh International Symposium on Precision Engineering Measurements and Instrumentation
Kuang-Chao Fan; Man Song; Rong-Sheng Lu, Editor(s)
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