| 摘要 |
PROBLEM TO BE SOLVED: To solve such the problem that conventionally ultrasonic waves are used in a diagnostic apparatus, constituted so that a sound transmitter and a sound receiver are arranged on the surface of concrete structure or the like, and acoustic elastic waves are transmitted to the interior of an object to be inspected and a receiving signals is analyzed to investigate and internal structural flaw, directionality is sharp and a range capable of being inspected at one transmitter position is narrow, and for example, in the inspection of a wide range, such as the wall surface of a tunnel or the like, a long time is required and there is restriction is the arrangement of the transmitter and the receiver. SOLUTION: Frequency which is 100 Hz-100 kHz lower than conventional is used. First, the frequency characteristics of an object 101 to be inspected are measured within this frequency range and frequency wherein a receiving signal becomes large is calculated. Next, the object 101 to be inspected is excited for a prescribed time by the calculated frequency, to measure the attenuation characteristics of vibration. Sound velocity is calculated from the calculated attenuation characteristics and the data base 113 of the attenuation characteristics and the sound velocity preliminarily calculated with respect to a similar material and the compression strength of the object to be inspected is calculated from a data base 113 of preliminarily calculated sound velocity and compression strength.
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