Application of an ultrasonic wave propagation field in the quantitative identification of cavity defect of log disc

Ultrasonic propagation field was introduced and verified through experiments.Propagation paths on cavity log cross-section were simulated though isolines.Internal cavity was identified by overlapping ultrasonic wave fields.Location and size of cavity was effectively determined in a high accuracy. This study introduced the concept of the ultrasonic propagation field in wood and verified its applicability through experiments conducted on a log disc. A green Betula costata log section was used in the ultrasonic propagation measurements. An ultrasonic wave detector (RSM-SY5) was used to measure the ultrasonic propagation time (UPT) on the cross section of the log sample. After the ultrasonication was completed on the non-defective log, five man-made cavities with diameters of 4, 8, 12, 16 and 20cm were made sequentially in the heart of the same log and utilized in the ultrasonic test. The even UPT values were then approximately outlined as isolines. Based on the UPT isolines, the ultrasonic propagation field in the log disc was simulated using MATLAB software, and the cavity was identified by overlapping the ultrasonic wave fields from different directions. The size of the cavity defect was proven to be effectively determined by overlying the maps of the ultrasonic wave propagation field through a cross section of the wood. The results indicated that the accuracy of detection values for cavity sizes with diameters of 4, 8, 12, 16 and 20cm were 83.2%, 84.8%, 94.0%, 95.8% and 96.2%, respectively.

[2]  Voichita Bucur,et al.  Factors affecting ultrasonic measurements in solid wood , 1994 .

[3]  Xiping Wang,et al.  Acoustic tomography for decay detection in black cherry trees , 2009 .

[4]  R. P. Chambers,et al.  Methods of measuring mechanical properties of plastics with high-frequency ultrasound , 1964, IEEE Transactions on Sonics and Ultrasonics.

[5]  Robert J. Ross,et al.  Nondestructive evaluation of standing trees with a stress wave method , 2007 .

[6]  Mats Gustafsson,et al.  Nondestructive detection of decay in living trees. , 2004, Tree physiology.

[7]  V. Bucur,et al.  Ultrasonic techniques for nondestructive testing of standing trees. , 2005, Ultrasonics.

[8]  R. Bruce Allison,et al.  Effect of Temperature on Acoustic Evaluation of Standing Trees and Logs: Part 2: Field Investigation , 2013 .

[9]  Li Li,et al.  Acoustic tomography in relation to 2D ultrasonic velocity and hardness mappings , 2011, Wood Science and Technology.

[10]  Robert J. Ross,et al.  Nondestructive evaluation of wood , 1994 .

[11]  Li Li,et al.  Pattern recognition and size determination of internal wood defects based on wavelet neural networks , 2009 .

[12]  Y. Tomikawa,et al.  Nondestructive Inspection of a Wooden Pole Using Ultrasonic Computed Tomography , 1986, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[13]  Robert J. Ross,et al.  Acoustic assessment of wood quality of raw forest materials - A path to increased profitability , 2007 .

[14]  Janice K. Wiedenbeck,et al.  Defining Hardwood Veneer Log Quality Attributes , 2004 .

[15]  Voichita Bucur,et al.  Acoustics of Wood , 1995 .

[16]  A. Habermehl.  A NEW NON-DESTRUCTIVE METHOD FOR DETERMINING INTERNAL WOOD CONDITION AND DECAY IN LIVING TREES. PART 1. PRINCIPLES, METHOD AND APPARATUS , 1982 .

[17]  Xiping Wang.  Fundamentals of Acoustic Measurements on Trees and Logs and Their Implication to Field Application , 2011 .

[18]  Robert J. Ross,et al.  Acoustic Evaluation of Wood Quality in Standing Trees. Part I. Acoustic Wave Behavior , 2007 .

[19]  Prof. Voichita Bucur.  Nondestructive Characterization and Imaging of Wood , 2003, Springer Series in Wood Science.