Stress wave tomography for the quantification of artificial hole detection in camphor trees (Cinnamomum camphora).

The purpose of this study was to evaluate defects/holes in trees using a stress wave tomo-graphic technique. Results revealed that there was a significant positive relationship of the residual disc diameter ratio with the stress wave velocity, and a negative relationship with a reduction in the corresponding stress wave velocity in the virtual radial direction. A difference in the mapped color and stress wave velocity between the hole area and its surrounding sound area was obvious, and when the ratio of the hole area to the cross-sectional area exceeded 2.3%, the hole was detectable by tomography. A significant positive relationship between wood density and stress wave velocity of the transverse section was found in this study. Moreover, above the fiber saturation point, stress wave velocities tended to decrease with increasing moisture contents using tomography. Experimental results could provide some vital information for detecting defect locations and sizes in trunk cross-sections.