The ultrasonic wave velocities of Japanese cedar columns were measured using a non-contact method. An air-coupled ultrasonic wave was propagated through the axial and lateral directions of wood. The velocities in the axial direction (VL) showed the minimum values around the pith. The averaged VL increased from 3600 m/s towards the outside of measurement area and attained the maximum values (=4010 m/s). The velocities in the lateral direction (VRT ) showed no tendency among measurement points. The averaged VRT was 1450 m/s. The velocities obtained using the non-contact method showed a significant positive relationship with those obtained using the contact method. The averaged ratio of VL to VRT was measured to be approximately 2.2 to 2.8. These ratios were in agreement with those from a contact method. These findings suggest that it is possible to measure the velocity in Japanese cedar columns with the non-contact method by using air-coupled ultrasonics.
References
[1]
Forestry Agency (2013) Annual Report on Trends in Forests and Forestry. Forestry Agency, Tokyo (in Japanese).
[2]
Hasegawa, M., Takata, M., Matsumura, J. amd Oda, K. (2011) Effect of Wood Properties on Within-Tree Variation in Ultrasonic Wave Velocity in Softwood. Ultrasonics, 51, 296-302. http://dx.doi.org/10.1016/j.ultras.2010.10.001
[3]
Mori, T., Yanase, Y., Tanaka, K., Kawano, K., Noda, Y., Mori, M., Kurisaki, H. and Komatsu, K. (2013) Evaluation of Compressive and Bending Strength Properties of Wood Damaged from Bio-Deterioration. Zairyo, 62, 280-285 (in Japanese with English Abstract). http://dx.doi.org/10.2472/jsms.62.280
[4]
Hasegawa, M., Yano, Y., Matsumura, J. and Oda, K. (2012) Prospects for Within-Tree Variation of the Acoustoelastic Behaviors in Japanese Cedar. NDT and E International, 49, 57-63. http://dx.doi.org/10.1016/j.ndteint.2012.03.010
[5]
Vun, R.Y., Hoover, K., Janowiak, J. and Bhardwaj, M. (2008) Calibration of Non-Contact Ultrasound as an On-Line Sensor for Wood Characterization: Effects of Temperature, Moisture and Scanning Direction. Applied Physics A: Materials Science & Processing, 90, 191-196. http://dx.doi.org/10.1007/s00339-007-4256-6
[6]
Dahmena, S., Ketatab, H.M., Hédi, B.G. and Hosten, B. (2010) Elastic Constants Measurement of Anisotropic Olivier Wood Plates Using Air-Coupled Transducers Generated Lamb Wave and Ultrasonic Bulk Wave. Ultrasonics, 50, 502-507. http://dx.doi.org/10.1016/j.ultras.2009.10.014
[7]
Hsu, D.K., Utrata, D. and Kuo, M. (2010) NDE of Lumber and Natural Fiber Based Products with Air-Coupled Ultrasound. Review of Progress in Quantitative Nondestructive Evaluation, 29, 1533-1540.
[8]
Sanabria, S.J., Furrer, R., Neuenschwander, J., Niemz, P. and Sennhauser, U. (2011) Air-Coupled Ultrasound Inspection of Glued Laminated Timber. Holzforschung, 65, 377-387. http://dx.doi.org/10.1515/hf.2011.050
[9]
Sanabria, S.J., Furrer, R., Neuenschwander, J., Niemz, P. and Sennhauser, U. (2013) Novel Slanted Incidence Air-Coupled Ultrasound Method for Delamination Assessment in Individual Bonding Planes of Structural Multi-Layered Glued Timber Laminates. Ultrasonics, 53, 1309-1324. http://dx.doi.org/10.1016/j.ultras.2013.03.017
[10]
Bucur, V. (2006) Acoustics of Wood. 2nd Edition, Springer-Verlag, Berlin.
[11]
Sanabria, S.J., Furrer, R., Neuenschwande, J., Niemz, P. and Schütz, P. (2015) Analytical Modeling, Finite-Difference Simulation and Experimental Validation of Air-Coupled Ultrasound Beam Refraction and Damping through Timber Laminates, with Application to Non-Destructive Testing. Ultrasonics, 63, 65-85.
http://dx.doi.org/10.1016/j.ultras.2015.06.013
[12]
Vun, R.Y., Wu, Q., Bhardwaj, M.C. and Sted, G. (2003) Ultrasonic Characterization of Structural Properties of Oriented Strandboard: A Comparison of Direct-Contact and Non-Contact Methods. Wood and Fiber Science, 35, 381-396.
[13]
Raffaella, S. and John, N.C. (2001) Non-Contact Ultrasonic Measurements in Food Materials. Food Research International, 34, 865-870. http://dx.doi.org/10.1016/S0963-9969(01)00110-7
[14]
Mishiro, A. (1996) Effect of Density on Ultrasonic Velocity in Wood. Mokuzai Gakkaishi, 42, 887-894.
