| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem of the conventional damage detecting apparatus and method for the inside of a material, detecting a nonlinear phenomenon by identifying frequencies in which: a signal having a large wave number is required to identify harmonics and partial harmonics; when a signal duration time is long, the accuracy of depth detection deteriorates, and a reflection wave from other parts and a reflection wave dependent on the shape of an analyte are measured thereby generating unnecessary noise signals; and it is difficult to surely detect damage at an early stage when the damage occurs.SOLUTION: Two ultrasonic waves having different frequencies to each other are used, one of which generates a nonlinear phenomenon and the other of which detects a nonlinear effect. Transmission timing of the ultrasonic wave for detecting a nonlinear phenomenon is controlled corresponding to respective positions of tension and compression stresses of the ultrasonic wave for generating a nonlinear phenomenon. A difference between reflection signals measured respectively at the positions of tension and compression stresses is detected to surely detect whether or not the nonlinear phenomenon occurs. |
