| 摘要 |
PURPOSE:To detect an abnormal part, by analyzing the frequencies of double- transmitted waves of the reflected ultrasonic waves that are vertically transmitted into a surface modified material as a body to be checked. CONSTITUTION:Ultrasonic waves are vertically emitted from an ultrasonic wave probe 4 into a surface modified material 1 as a body to be checked. Said waves become double-transmitted waves when they are transmitted through a film 2 of the modified material 1 twice. The waves are received with an ultrasonic-wave flaw detecting device 5. The double-transmitted waves are converted into digital waveforms through a digital oscilloscope 6, and the results are inputted into a computer 7. The frequency of each digital waveform is analyzed in a FET board 9, and a frequency spectrum is obtained. The peak frequency of the spectrum in a broad band is picked up. The intensity peak value within a specified band width wherein the peak frequency of the frequency spectrum for the double-transmitted waves at a sound part is the center is picked up. The characteristic values at the sound part are used as the reference values, and the changing values are classified. Thus, the distribution of defects is obtained. |
