Non-Contact Velocity Measurement of Japanese Cedar Columns Using Air-Coupled Ultrasonics

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.

[1]  A. Mishiro.  Effect of density on ultrasonic velocity in wood , 1996 .

[2]  Y. Yanase,et al.  Evaluation of Compression and Bending Strength Properties of Wood Damaged from Bio-Deterioration , 2013 .

[3]  Roman Furrer,et al.  Air-coupled ultrasound inspection of glued laminated timber , 2011 .

[4]  Junji Matsumura,et al.  Effect of wood properties on within-tree variation in ultrasonic wave velocity in softwood. , 2011, Ultrasonics.

[5]  John J. Janowiak,et al.  Calibration of non-contact ultrasound as an online sensor for wood characterization: Effects of temperature, moisture, and scanning direction , 2007 .

[6]  Qinglin Wu,et al.  ULTRASONIC CHARACTERIZATION OF STRUCTURAL PROPERTIES OF ORIENTED STRANDBOARD: A COMPARISON OF DIRECT-CONTACT AND NON-CONTACT METHODS 1 , 2003 .

[7]  Roman Furrer,et al.  Novel slanted incidence air-coupled ultrasound method for delamination assessment in individual bonding planes of structural multi-layered glued timber laminates. , 2013, Ultrasonics.

[8]  Bernard Hosten,et al.  Elastic constants measurement of anisotropic Olivier wood plates using air-coupled transducers generated Lamb wave and ultrasonic bulk wave. , 2010, Ultrasonics.

[9]  Junji Matsumura,et al.  Prospects for within-tree variation of the acoustoelastic behaviors in Japanese cedar , 2012 .

[10]  J. Coupland,et al.  Non-contact ultrasonic measurements in food materials , 2001 .

[11]  Roman Furrer,et al.  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. , 2015, Ultrasonics.

[12]  David K. Hsu,et al.  NDE OF LUMBER AND NATURAL FIBER BASED PRODUCTS WITH AIR COUPLED ULTRASOUND , 2010 .