| 摘要 |
The invention relates to a non-destructive flaw detection technique for detecting a flaw of a structure by using a guide wave ultrasonic wave. A method for solving both the problem that the flaw detection waveform distorts and the spatial resolution significantly lowers because of the adverse influence of the velocity dispersibility of the velocity-dispersible guide wave ultrasonic wave the propagation velocity of which varies with the frequency and the problem that the S/N ratio on the flaw detection signal must be improved has been sought. A novel process algorithm adaptable to the velocity-dispersible guide wave ultrasonic wave has been devised. From reception time wave information on the later received time wave, excitation time wave information, and guide wave ultrasonic wave velocity dispersion information, the spatial distribution of the flaws in the structure and the spatial wave pulse compression waveform corresponding to the convolution waveform with autocorrelation function of the excitation spatial wave which is the spatial distribution of the excitation spatial wave are computed by using a chirp signal with a wide band as the excitation time wave. With this, a flaw detection waveform having a high spatial resolution and a high S/N ratio is realized. |
