| 摘要 |
PROBLEM TO BE SOLVED: To realize a method for detecting a surface fault capable of detecting the fault smaller than a width of an ultrasonic beam without extremely little evaluating. SOLUTION: A surface wave containing a plurality of frequency components in a transmitted wave from a transmitting probe 4 is received by a receiving probe 5, a vibration is converted into an electric signal which is transmitted to a receiver 6, Fourier-transformed by a spectrum analyzer 7, and sent to a calculator 8. The calculator 8 measures a frequency distribution of transmittance of an ultrasonic wave, regression calculates the frequency distribution of the measured transmittance as a linear combination in which a sum of coefficients (undecided coefficients) of a formula representing the distribution of the transmittance of the transmitted wave attenuated in response to a depth of a fault having a sufficiently large amplitude to the width of the ultrasonic wave and a formula representing the frequency distribution of the wave transmitted through a healthy surface becomes a constant, and measures the depth and the magnitude of the fault according to the result of the calculation. |
