Abstract
A new method is proposed to detect a tilted planar flaw on the back surface of a plate using the interference of ultrasonic waves. Parameters for flaw evaluation are developed and examined through experimental results for artificial flaws. The existence of the flaw and its height are estimated by parameter Bh, which shows the first amplitude of the interference fringe. The effect of tilt angle of the flaw on parameter Bα, which indicates the amount of asymmetry of the interference fringe along the direction normal to the flaw, is investigated. Flaws larger than 0.5 mm in height can be detected using the present method with a tilt angle of 20°from the normal direction of the inspection surface.
