Detection of defects in red oak deckboards by ultrasonic scanning

Abstract

Experiments were conducted to detect defects in red oak (Quercus rubra, L.) deckboards by ultrasonic scanning. Scanning of the deckboards was carried out with two rolling transducers in a pitch-catch arrangement with pallet parts moving between the transducers at 70 ft/m and 220 ft/m. Data were collected, stored and processed using LabViewTM software. The defects examined were sound and unsound knots, bark pockets, holes, decay, and wane. Three deckboard samples (fresh cut and unplaned condition) were scanned for each defect type. Defects were characterized on the basis of time of flight, pulse energy, and pulse duration of the received signals. Results demonstrated that defected wood can be distinguished from clear wood by observing the variation in received signals. Ultrasonic signal parameters are more sensitive to unsound knots, decay, bark pockets, holes, and wane, compared to sound knots. This study demonstrates the feasibility of on-line inspection of green (high moisture content) and rough (unplaned) red oak deckboards.

Citation

Kabir, Mohammed F.; Schmoldt, Daniel L.; Schafer, Mark E. 2000. Detection of defects in red oak deckboards by ultrasonic scanning. Proceedings, 4th International Conference on Image Processing and Scanning of Wood. 89-96.