Journal of the Korean Society for Aeronautical & Space Sciences (한국항공우주학회지)

The Korean Society for Aeronautical and Space Sciences (한국항공우주학회)
권호 표지
DOI QR코드

DOI QR Code

The effects of the thickness variation on the propagation of Lamb waves in a composite plate

복합재 평판의 두께변화가 램파의 전파에 미치는 영향

  • Published : 2006.06.30
Download PDF
⟨ Previous Next ⟩

Abstract

This study experimentally investigates the characteristics of Lamb wave propagating in a composite plate of varied thickness. In practical aerospace structures, there are so many parts that have varied thickness. Therefore, in order to employ the Lamb wave in a structural health monitoring of those parts, it is necessary to understand correctly the characteristics of Lamb wave for the structure with thickness variation. Thin surface-bonded piezoelectric transducers, which have great potential in integrated monitoring systems for structural health, were used to generate and receive Lamb waves. The predicted propagation velocity under the assumptions of ideal mode conversions was compared with the experimentally measured one. The validity of the results was supported by the frequency analysis of the signals. Consequently, the results show that the transient region is occurred when Lamb waves propagate across the region that thickness variation over some gradient exists.

본 연구는 두께변화가 있는 복합소재 평판을 전파하는 램파의 전파특성을 실험을 통하여 살펴보았다. 상용 항공우주구조물에는 두께변화가 존재하는 부품이 많이 사용되고 있고 구조변화에 의해 두께가 변할 수도 있기 때문에 구조건전성 모니터링을 위하여 램파를 사용하고자 한다면, 이러한 구조물에 대한 램파의 특성을 면밀히 분석해 볼 필요가 있다. 본 연구는 얇은 두께의 PZT를 구조물 표면에 부착하여 실험을 수행하였다. 두께변화가 있는 전파경로를 선택하여 측정된 신호의 전파속도 및 주파수 분석 결과를 이상적 전파조건과 비교를 통하여 두께변화가 존재하는 영역에서 전파특성의 변화가 이루어지는 과정 중에 전이영역이 발생함을 제시하였다.

Keywords

References

  1. Dalton R.P., Cawley P. and Lowe M.J.S., 'The potential of guided waves for monitoring large area of metallic aircraft fuselage structure', J. Nondestructive Evaluation, Vol. 20, No. 1, 2001, pp.29-46 https://doi.org/10.1023/A:1010601829968
  2. Paget C.A., 'Contribution to active health monitoring of aerospace composite structures by embedded piezoceramic transducers', 2001 Ph.D. Report 0117, Valenciennes University
  3. Spillman Jr. W.B., Sirkis J.S. and Gardiner P.T., 'Smart materials and structures; what are they?', Smart Material and Structure, 1996, Vol. 5, No. 3, 1996, pp. 247-254 https://doi.org/10.1088/0964-1726/5/3/002
  4. Kessler S.S., Spearing S.M., 'In-situ Sensor-Based Damage Detection of Composite Materials for Structural Health Monitoring', AIAA Journal, Vol. 154, 2002
  5. Ye L. and Su Z., 'A damage identification technique for CF/EP composite laminates using distributed piezoelectric transducers', J. Composite structures, Vol. 57, 2002, pp.465-471 https://doi.org/10.1016/S0263-8223(02)00115-0
  6. Kessler S.S., Spearing S.M. and Soutis C., 'Damage detection in composite materials using Lamb wave methods', Smart Material and Structure, Vol. 11, 2002, pp.269-278 https://doi.org/10.1088/0964-1726/11/2/310
  7. Grondel S., Assaad J., Delebarre C. and Levin K., 'Design of optimal configuration for generating $A_{0}$ Lamb mode in a composite plate using piezoceramic transducers', J. Acoustic Soc. Am., Vol. 112, No. 1, 2002, pp. 84-90 https://doi.org/10.1121/1.1481062
  8. Wilcox P.D., Lowe M.J.S. and Cawley P., 'Mode and Transducer Selection for Long Range Lamb Wave Inspection', J. Intelligent Material Sys. and Structure, Vo.12, 2001, pp. 553-565 https://doi.org/10.1177/10453890122145348
  9. Rose J., 'Ultrasonic Waves in Solid Media', Cambridge University Press; 1999
  10. 한정호, 김천곤, '두께변화가 있는 복합재평판의 램파 전파특성', 복합재료학회지, Vol. 18, No. 2, Apl. 2005, pp. 41-51
  11. Signal processing toolbox user's guide, version 4. (Natik, MA, USA: The Math works, Inc., 1998)