An ultrasonic defect detection system for radiata pine lumber based on 0.5
Mhz sound transmission through wood was tested. The feasibility of detectin
g knots, grain deviation, and growth ring angle with this system was invest
igated as well. The knot material, area of knot influence, and growth ring
angle were significantly correlated to wave velocity. The ultrasonic scanni
ng showed good agreement with visual prediction.