On Nondestructive Evaluation of Wood Materials Using Ultrasonic Techniques

In this work, a wood material was nondestructively characterized and a technique was developed to measure ultrasonic velocity in wood using automated data acquisition software. It is desirable to perform nondestructive evaluation (NDE) to assess material properties and absorption of wood because wood is a natural composite and often inhomogeneity. Several ultrasonic techniques were applied to wood for the evaluation of variations material properties. The variation of ultrasonic velocity was measured and found to be somewhat consistent with those in infiltrated area in the course of nature absorption. Low frequency (1 MHz) through-transmission scans based on both amplitude and time-of-flight of the ultrasonic pulse were used for mapping out the material property inhomogeneity. These results were compared with those obtained by dry-coupling ultrasonics. A good correlation was found between ultrasonic velocity (a pulse overlap and peak-delay measurement method) and C-scan image signal based on peak-to-peak amplitude.