Arborsonic Decay Detection

The Arborsonic Decay Detector (ADD) uses ultrasound to detect and evaluate internal decay/defects in standing and felled timber. The ADD evolved from a similar instrument that was developed by Fujikura to test wooden telegraph poles.

The ADD is lightweight (1.1kg), rugged and weatherproof. An ultrasonic signal (77kHz) is passed through the tree between two transducers (transmitter and receiver). The signal speed is very fast - about 2000 metres/sec. The signal prefers to travel in the solid part of the wood structure. So, if the wood structure is good then the time taken for the signal to travel is optimised. However, if decay or defects are present the signal has to pass through the tree using a non-direct route. Consequently, the time taken is longer. There is a direct correlation between this increase in propagation time and the extent of decay/defect present.

Testing is essentially independent of species and season. As the ADD is very sensitive (propagation times are measured to one millionth of a second) all types of decay in incipient and advanced stages can be detected.

Ultrasonic propagation delay time in wood depends on the extent and depth of internal decay. Based on the experimental relation between delay time and decay depth, this detector measures and evaluates the existence and extent of internal decay in wood.