| 摘要 |
PURPOSE:To measure the depth of cracking accurately, by gradually expanding the distances of an oscillating element and an oscillation receiving element from the cracking as set at a symmetrical position with respect to the cracking to determine a distance at which an initial phase of a propagation waveform is inverted. CONSTITUTION:An oscillating element T and an oscillation receiving element R connected to an ultrasonic speed measuring device 1 are set at a symmetrical position with respect to a cracking C on the outer surface of a sample A. Then, a pulse waveform voltage of 10kHz is applied to the oscillating element T to generate an ultrasonic wave and the ultrasonic wave propagating through the sample A is detected with the oscillation receiving element R to be converted into a propagation signal, which is sent to an amplifier 2 to amplify while being passed through a band pass filter. The signal is converted into digital from analog with a transient memory 3 and displayed on an oscilloscope 5 via a waveform processor 4. As distances (a) to the oscillating element T and the oscillation receiving element R from the center of the cracking are expanded gradually, the initial phase of the propagation waveform is inverted downward as shown by the arrow (y) from upward as shown by the arrow (x) when the distances (a) exceed the depth of the cracking C, thereby enabling measurement of the depth of the cracking. |
