ABSTRACT
The application of ultrasonic guided waves (GWs) in evaluating the structural integrity of timber utility poles has shown high potential in detecting and assessing various types of defects. Yet, the effects of temperature and moisture content (MC) on the propagation of GWs are not well-understood and the uncertainty that may influence the results is not well-investigated. This study aims to scrutinize the effect of MCs (0% to 24%) and temperatures (-20º till 100ºC) on the propagation characteristics of bulk wave, longitudinal and circumferential GWs in-cylinder timbers excited at 10-20kHz. The results showed that at 0% MC the velocity change is insignificant due to absence of water. As MC increases below the Fiber Saturation Point (FSP), the difference in mode velocities is 20% at -20ºC, 50% at 100ºC, and 40% upon varying the timber’s temperatures. Above FSP, the difference was less than 2% at fixed temperatures and 58% under temperatures variations.
