| 摘要 |
PURPOSE:To execute the measurement of the depth of a crack with high accuracy by deriving an ultrasonic wave propagation time between a transmitter and a receiver which have been placed symmetrical to the centerline of a crack part, between plural spots, and calculating the crack depth, based on this propagation time. CONSTITUTION:An ultrasonic transmitter 1 and an ultrasonic receiver 2 are arranged symmetrical to the centerline of a crack part 6 of a body to be inspected 5. At the time of measurement, transmission and reception are executed, while varying a distance between the transmitter 1 and the receiver 2, and an ultrasonic wave propagation time in each distance is counted successively. Between the transmitter and the receiver which have been placed to an equal distance ai to the right and left from the crack 6, and an acoustic wave propagation time Ti, a relation of Ti<2>alpha ai<2> exists, therefore, by deriving a proportional coefficient and a constant term of both of them by a method of least square, the depth (y) of the crack part 6 can be measured with high accuracy. |
