Journal of the Korean Society for Nondestructive Testing (비파괴검사학회지)

The Korean Society for Nondestructive Testing (한국비파괴검사학회)
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Lamb Wave Technique for Ultrasonic Nonlinear Characterization in Elastic Plates

판재의 초음파 비선형 특성평가를 위한 Lamb Wave 기법

  • Received : 2010.08.10
  • Accepted : 2010.10.08
  • Published : 2010.10.30
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Abstract

Since the acoustic nonlinearity is sensitive to the minute variation of material properties, the nonlinear ultrasonic technique(NUT) has been considered as a promising method to evaluate the material degradation or fatigue. However, there are certain limitations to apply the conventional NUT using the bulk wave to thin plates. In case of plates, the use of Lamb wave can be considered, however, the propagation characteristics of Lamb wave are completely different with the bulk wave, and thus the separate study for the nonlinearity of Lamb wave is required. For this work, this paper analyzed first the conditions of mode pair suitable for the practical application as well as for the cumulative propagation of quadratic harmonic frequency and summarized the result in for conditions; (1) phase matching, (2) non-zero power flux, (3) group velocity matching, and (4) non-zero out-of-plane displacement. Experimental results in aluminum plates showed that the amplitude of the secondary Lamb wave and nonlinear parameter growed up with increasing propagation distance at the mode pair satisfying the above all conditions and that the ration of nonlinear parameters measured in Al6061-T6 and Al1100-H15 was closed to the ratio of the absolute nonlinear parameters.

음향 비선형성은 재료 물성의 미세한 변화에 민감하기 때문에, 이를 측정하는 비선형 초음파 기술은 재료의 열화나 피로를 평가할 수 있는 기법으로 연구되어 왔다. 하지만 벌크파를 이용하는 일반적인 비선형 초음파 기법은 얇은 판재에 적용하는 것에는 여러 한계가 있다. 이와 같은 경우에는 비선형 Lamb 파의 사용을 생각할 수 있지만, Lamb 파는 벌크파와 매우 다른 전파 특성을 가지고 있어 그 비선형 특성에 대한 별도의 연구를 필요로 한다. 이를 위해 본 연구에서는 Lamb 파에서 비선형성에 의해 전파하면서 누적 성장할 수 있는 2차 고조파 모드의 발생 조건을 분석하였으며, 그 결과 네 가지 조건, 즉 (1) phase matching, (2) non-zero power flux, (3) group velocity matching, (4) non-zero out-of-plane displacement 를 제시하였다. 그리고 제시된 조건으로 알루미늄 판재에 대책 실험한 결과 이론 예측과 동일하게 전파 거리에 따라 2차 고조파 성분의 크기와 비선형 파라미터가 증가하였고, Al6061-T6 과 Al1100-H14에서 측정된 상대적인 비선형 파라미터의 비율이 이론적인 비율과 근접함을 보였다.

Keywords

Acknowledgement

Supported by : 한국연구재단

References

  1. A. Hikata, B. B. Chick, and C. Elbaum, "Effect of dislocations on finite amplitude ultrasonic waves in aluminum," Applied Physics Letters, Vol. 3, No. 11, pp. 195-197 (1963) https://doi.org/10.1063/1.1753845
  2. T. Suzuki, A. Hikata and C. Elbaum, "Anharmonicity due to glide motion of dislocations," Journal of Applied Physics, Vol. 35, No.9, pp. 2761-2766 (1964) https://doi.org/10.1063/1.1713837
  3. A. Hikata, B. B. Chick and C. Elbaum, "Dislocation contribution to the second harmonic generation of ultrasonic waves," Journal of Applied Physics, Vol. 36, No.1, pp. 229-236 (1964)
  4. J. H. Cantrell, W. T. Yost, "Acoustical harmonic generation from fatigue-induced dislocation dipoles," Philosophical Magazine A, Vol. 69, No.2, pp. 315-326 (1994) https://doi.org/10.1080/01418619408244346
  5. J. K. Na, J. H. Cantrell, and W. T. Yost, "Linear and nonlinear ultrasonic properties of fatigued 410Cb stainless steel," Review of Progress in Quantitative Nondestructive Evaluation, Vol. 15, pp. 1347-1351 (1996)
  6. K. Y. Jhang, "Applications of nonlinear ultrasonics to the NDE of material degradation," IEEE UFFC, Vol. 47, No.3, pp. 540-548 (2000)
  7. Jaeik Lee, Taehun Lee and Kyung-Young Jhang, "Evaluation of surface fatigue degradation using acoustic nonlinearity of surface wave," Journal of the Korean Society for Nondestructive Testing, Vol. 29, No.5, pp. 415-420 (2009)
  8. J. Herrmann, J. Y. Kim, L. J. Jacobs, J. Qu, J. W. Littles and M. F. Savage, "Assessment of material damage in a nickel-base superalloy using nonlinear Rayleigh surface waves," Journal of applied physics, Vol. 99, 124913 (2006) https://doi.org/10.1063/1.2204807
  9. M. Deng, P. Wang and X. Lv, "Experimental observation of cumulative second-harmonic generation of Lamb-wave propagation in an elastic plate," Journal of physics D: Applied physics, Vol. 38, pp. 344-353 (2005) https://doi.org/10.1088/0022-3727/38/2/020
  10. M. Deng, "Characterization of surface properties of a solid plate using nonlinear Lamb wave approach," Ultrasonics, Vol. 44, pp. e1157-e1162 (2006) https://doi.org/10.1016/j.ultras.2006.05.158
  11. W. J. N. de Lima, M. F. Hamilton, "Finite-amplitude waves in isotropic elastic plates," Journal of Sound and Vibration, Vol. 265, pp. 819-839 (2003) https://doi.org/10.1016/S0022-460X(02)01260-9
  12. W. J. N. de Lima, M. F. Hamilton, "Finite amplitude waves in isotropic elastic waveguides with arbitrary constant cross-sectional area," Wave Motion, Vol. 41, pp. 1-11 (2005) https://doi.org/10.1016/j.wavemoti.2004.05.004
  13. Jaeik Lee, Goodo Kwon, Taehun Lee and Kyung-Young Jhang, "Acoustic nonlinearity of surface wave and experimental verification of characteristics," Journal of the Korean Society for Nondestructive Testing, Vol. 29, No.4, pp. 344-350 (2009)
  14. W. T. Yost and J. H. Cantrell, "The effect of artificial aging of aluminum 2024 on its nonlinear parameter," Review of Progress in Quantitative Nondestructive Evaluation, Vol. 12, pp. 2067-2073 (1993)