Wooden utility poles are used worldwise to carry overhead cables for electric, telephone and cable TV services. About 130 to 160 million poles are currently in use in the US alone. These poles may have an average service life of 30 years. A Safety Code requires pole replacement when one-third of the load carrying capacity of the pole is lost. Such a decrease is normally due to insect infestation. No good commercially available methods are currently available for that application. As a result, visually inspection and replacing poles can be very costly. The industry has been interested in a technology which could be used to accurately predict pole condition. Based on experience with the detection of defects in engineering materials using ultrasound, initial studies of ultrasonic testing have been conducted on samples of these poles. This study used a chartesian ultrasonic plane wave propagation to characterize the elastic properties os wood structures. The results showed that this method of examiantion can indeed be extended to the determination of internal defects in wooden poles, and that such results could be applied to improve the design of appropriate testing equipment for wooden utility poles applications. See also Article of UTonline 12/96: J. L. Sandoz Ultrasonic solid wood evaluation in industrial applications |
|
|Table of Contents ASNT Fall '97| |Abstract Database| |NDTnet| |