Browse > Article
http://dx.doi.org/10.3795/KSME-A.2012.36.12.1511

Flaw Detection in Pipe-Welded Zone by Using Wavelet Transform and SH-EMAT  

Lee, Jin-Hyuk (Graduate School of Energy and Environment, Seoul Nat'l Univ. of Science and Technology)
Kim, Dae-Hyun (Dept. of Mechanical & Automotive Engineering, Seoul Nat'l Univ. of Science and Technology)
Publication Information
Transactions of the Korean Society of Mechanical Engineers A / v.36, no.12, 2012 , pp. 1511-1519 More about this Journal
Abstract
Pipe structures contain many welded zones, and ultrasonic tests are increasingly being performed by using automated testing devices in order to evaluate the weld integrity. An electromagnetic acoustic transducer (EMAT) is a noncontact transducer that can transmit or receive ultrasonic waves without a couplant. Furthermore, it can easily generate specific guided waves such as SH (shear horizontal) or Lamb waves by altering the design of the coil and magnet. Therefore, an EMAT should be useful for application to an automated ultrasonic inspection system. In this study, SH waves generated using an EMAT were applied to inspect the pipe-weld zone. To analyze the specific SH mode (SH0) from the SH wave signals, wavelet transform was applied. It was found that flaws could be detected precisely because the intensity of the $SH_0$ mode-frequency, which is analyzed by using wavelet transform, is proportional to the length of the flaw.
Keywords
Electromagnetic Acoustic Transducer(EMAT); Shear Horizontal wave(SH-wave); Wavelet Transform; Noncontact Ultrasonic Testing;
Citations & Related Records
Times Cited By KSCI : 2  (Citation Analysis)
연도 인용수 순위
1 Park, I. K., Park, U. S., Ahn, H. K., Kwun, S. I. and Byeon, J. W., 2000, "Wavelet Analysis of Ultrasonic Echo Waveform and Application to Nondestructive Evaluation," J. of KSNT, Vol. 20, No. 6, pp. 501-510.
2 Bussow, R., 2007, "An Algorithm for the Continuous Morlet Wavelet Transform," Mechanical System and Signal Processing, Vol. 21, pp. 2970-2979.   DOI   ScienceOn
3 Varma, V. K., Tucker, R., Kercel, S., Rose, J., Luo, W. and Zhao, X., 2004, "Pipeline Flaw Detection Using Shear EMAT and Wavelet Analysis," GTI's Natural Gas Technologies II, Pheonix, AZ, February 8-11.
4 Mertins, A., 1999, "Signal Analysis: Wavelets, Filter Banks, Time-Frequency Transforms, and Applications," J. WILEY, Chichester, England.
5 Park, I. K. and Ahn, H. K., 2001, "Time-Frequency Analysis of Lamb Wave Mode," J. of KSMTE, Vol. 10, No. 1, pp. 133-140.
6 Rose, J. L., 1999, "Ultrasonic Waves in Solid Media," Cambridge University Press, UK.
7 Achenbach, J. D., 1984, "Wave Propagation in Elastic Solids," North-Holland, New York.
8 Lee, J.-H., Lim, S.-J., Park, I.-K. and Kim, D.-H., 2010, "Development of Automated Ultrasonic Testing System for Partial Joint-Weld of Heat Exchanger's Header to Tube in Power Plant," J. of KSNT, Vol. 30, No. 4, pp. 367-372.
9 Lee, J.-H., Park, I.-K., Kim, Y.-K. and Kim, D.-H., 2011, "Evaluation of Thickness Reduction in Steel Plate by Using SH-EMATs," J. of KSNT, Vol. 31, No. 1, pp. 38-43.
10 Park, I. K., Kim, H. M., Park, T. S., Kim, Y. G., Cho, Y. S. and Song, W. J., 2006, "Non-Contact Ultrasonic Inspection Technology of Fillet Weldments Monitoring," Key Engineering Materials, Vol. 321-323, pp. 513-517.   DOI
11 Hirao, M. and Ogi, H., 2003, "EMATs for Science and Industry Noncontacting Ultrasonic Measurements," Kluwer Academic Publisher, Boston.
12 Fujisawa, K., 2002, "Application of EMAT to Steel and Nonferrous Metal," J. of JSNDI, Vol. 51, No. 2, pp. 68-73.