Journal of the Korean Wood Science and Technology

The Korean Society of Wood Science & Technology (한국목재공학회)
권호 표지
DOI QR코드

DOI QR Code

Evaluation of Influences of Artificial Defect of Wood Deck Using Non-destructive Ultrasonic Testing

목재 데크재의 초음파 비파괴시험에 의한 인위적인 결함의 영향평가

  • 오세창 (대구대학교 생명환경대학 산림자원학과)
  • Received : 2015.09.17
  • Accepted : 2015.10.21
  • Published : 2016.01.25
Download PDF
⟨ Previous Next ⟩

Abstract

Non-destructive ultrasonic testing was applied to evaluate the performance of wood deck material with hole as artificial defect. Ultrasonic velocities and modulus of elasticity were measured according to different diameters and numbers of holes, and comparative analysis to each data were done. From the results, ultrasonic velocities and modulus of elasticity decreased with an increase in the hole size and showed a negative linear correlation with the size of hole, respectively. As the hole size increased, ultrasonic velocities decreased, but their difference was small in the case of the hole size under 15 mm. Also, ultrasonic velocities and modulus of elasticity decreased with increasing the number of holes and showed a strong negative linear correlation to the number of holes. As the number of holes increased, ultrasonic velocities decreased to 3.5%, but modulus of elasticity decreased to 27%. Therefore, the number of holes showed greater influence to modulus of elasticity than ultrasonic velocity. Overall, the size and number of holes influenced to ultrasonic velocity and modulus of elasticity, and their influence will be greater as the size and number of holes increases. These results suggested that several ultrasonic parameters rather than a single ultrasonic velocity should be applied to detect small defects in wood decking materials.

목재 데크재에 인위적인 결함인 구멍을 부여하고 이들의 성능평가를 위해 초음파 비파괴 시험법을 적용하였다. 구멍의 크기와 개수를 달리하여 각각에 대한 초음파 전달속도를 측정하고 탄성계수를 산정하여 그 영향을 비교분석하였다. 시험결과 구멍의 크기가 커짐에 따라 초음파 전달속도와 탄성계수는 감소하였으며 이들 상호간에는 직선상관관계를 보였다. 구멍의 크기가 증가하면 초음파의 전달 길이는 증가하며 이에 따라 초음파속도는 감소하였지만 구멍의 크기가 15 mm 이하로 작은 경우에는 구멍이 없는 부재에 비해 그 차이가 작게 나타났다. 구멍의 개수가 많아짐에 따라 초음파 전달속도와 탄성계수는 감소하였으며 이들 상호간에는 높은 직선상관관계를 보였다. 구멍의 개수가 3개인 경우 초음파속도는 약 3.5% 정도 감소한데 비하여 탄성계수는 27% 정도로 현저히 감소하여 더 큰 감소경향을 나타내었다. 이들의 결과로부터 구멍의 크기와 개수는 초음파 전달속도와 탄성계수에 영향을 미치며 구멍의 크기가 크고 개수가 많아질수록 그 영향은 더욱 커질 것으로 여겨진다. 또한 작은 결함의 탐지를 위해서는 초음파 전달속도에만 의지할 것이 아니라 여러 초음파 변수를 고려하여 적용하는 방법을 고려하여야 할 것으로 생각된다.

Keywords

References

  1. Carrasco, V.M., Teixeira, A.R. 2012. Methodology for inspection of wood pathologies sing ultrasonic pulses. Cerne, Lavras 18(3): 479-486. https://doi.org/10.1590/S0104-77602012000300016
  2. Hwang, W.J., Lee, M.H., Park, Y.R., Lee, D.H. 2014. The change of ultrasonic transmission velocity by wood decay. Journal of the Korean Wood Science and Technology 42(2): 214-221. https://doi.org/10.5658/WOOD.2014.42.2.214
  3. Jang, S.J. 2000. Effect of moisture content and slope of grain on ultrasonic transmission speed of wood. Journal of the Korean Wood Science and Technology 28(2): 10-18.
  4. Kabir, M.F., Araman, P.A. 2002. Non-destructive evaluation of defects in wood pallet parts by ultrasonic scanning. 13th International Symposium on Nondestructive Testing of Wood, California, USA.
  5. Lee, J.J., Kim, G.M., Bae, M.S. 2003. Investigation of transmission process for ultrasonic waves in wood. Journal of the Korean Wood Science and Technology 31(2): 31-37.
  6. Lin, W., Wu, J. 2013a. Non-destructive testing of wood defects based on ultrasonic technology. Applied Mechanics and Materials 401-403: 1124-1128. https://doi.org/10.4028/www.scientific.net/AMM.401-403.1124
  7. Lin, W., Wu, J. 2013b. Non-destructive testing of wood defects based on stress wave technology. TELKOMNIKA 11(11): 6802-6807.
  8. Lin, W., Wu, J. 2013c. Non-destructive testing of wood defects for Korean pine in Northwest China based on ultrasonic technology. Proceedings of IEEE International Conference on Signal Processing, Communication and Computing. Yunan, China.
  9. Mestre, P., Calcada, A., Carvalho, N., Serodio, C., Couto, P., Matias, J., Melo-Pinto, P., Morais, J. 2013. Low-cost ultrasonic probe to assess wood defects and parameters. Proceedings of the World Congress on Engineering Vol.II, WCE 2013, London, U.K.
  10. Park, C.Y., Kim, G.C. 2014. Evaluation of modulus of elasticity of wood exposed to accelerated weathering test by measuring ultrasonic transmission time. Journal of the Korean Wood Science and Technology 42(3): 275-281. https://doi.org/10.5658/WOOD.2014.42.3.275
  11. Park, J.C., Hong, S.I. 2008. Determination of localized defects in wood by the transfer time of ultrasonic waves. Journal of the Korean Wood Science and Technology 36(1): 61-68.
  12. Raquel, G., Domingos, G.P.C., Chiara, B.S., Fernando, A.F.B. 2011. Behavior of ultrasonic waves propagation in presence of holes on Pequia (Aspidosperma desmanthum) wood. 17th International Nondestructive Testing and Evaluation of Wood Symposium, Sopron, Hungry.
  13. Shaji, T., Somayaji, S., Mathews, M.S. 2000. Ultrasonic pulse velocity technique for inspection and evaluation of timber. Journal of Materials in Civil Engineering Vol. 12(2): 180-185. https://doi.org/10.1061/(ASCE)0899-1561(2000)12:2(180)
  14. Yavari, A., Roohnia, M., Khademi-Eslam, H., Yavari, E. 2011. Hole influence and FFT variation inspection in poplar wood by free vibration method. 17th International Nondestructive Testing and Evaluation of Wood Symposium. Sopron, Hungry.