SNR Improvement of AE Signal for Detection of Gas Leak from Tubes under Vibratory Environment

  • Published : 2007.06.30

Abstract

Detection of gas leak from a tube is a very important issue in the quality control of machines such as the heat exchanger of an air-conditioner, because leakage of operating gas directly reduces the performance of machines. The acoustic emission (AE) method is a common way to detect leak of gas, however its application under the environment of mechanical vibration is restricted since most AE detectors are very sensitive to external vibration noise. In order to overcome this problem, we propose a method based on the mode analysis of the Lamb wave. In this method, the dominant Lamb mode and its frequency are found first, and then a proper band-pass filter is used to retain only this frequency component. In this way, we could improve the SNR (signal-to-noise ratio) of AE signal generated by gas leak from the tube even under vibratory environment.

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References

  1. Guo D., Mal A. K., and Ono K. (1996) Wave Theory of Acoustic Emission in Composite Laminates, Journal of Acoustic Emission, Vol. 14, pp. S19-46
  2. Kim, H. M., Lee T. H. and Jhang K. Y. (2006) Non-Contact Single-Mode Guided Wave Technique by the Combination of Wavelength-Matched Laser Generation and Angle-Matched Leak Wave Detection, Key Engineering Materials, Vols. 326-328, pp. 477-480
  3. Lee, S. K. (2004) Leak Detection and Evaluation for Power Plant Boiler Tubes Using Acoustic Emission, Journal of the Korean Society for Nondestructive Testing, Vol. 24, No. 1, pp. 45-51
  4. Lord, A. E., Deisher, J. N. and Koerner, R. M. (1977) Attenuation of Elastic Waves in Pipelines as Applied to Acoustic Emission Leak Detection, Materials Evaluation, Vol. 55, No. 1, pp. 49-54
  5. Rose, J. L. (1999) Ultrasonic Waves in Solid Media, Cambridge University Press, Cambridge, UK, pp. 101-131
  6. Yoshihiro, M., Takemoto, M., Cho, H., and Ono, K. (1998) Characterization of the Lamb Waves Produced by Local Impact Fracture in Brittle Thin Plates, Progress in Acoustic Emission IX, Part III, pp. 1-10