Feasibility of ultrasonic tomography for nondestructive testing of decay on living trees

Both laboratory and field ultrasonic measurements were carried out to assess the feasibility of ultrasonic tomography for non-invasive testing of living trees. Trees with internal decay were investigated and later cut down. The laboratory measurements, performed on wood disks and specimens, led to the quantitative assessment of the reliability of the tomographic result. Statistical analysis of data allowed considerations to be made on the main aspects connected to the tomographic imaging, such as uncertainty, spatial resolution and anisotropy. The obtained results show that the tomographic image of the ultrasonic velocity distribution is in good agreement with the distribution of the wood decay in the investigated section and the proposed methodology therefore seems to be an improvement on currently used surveying methods.