Patent ID: 8483978

Claim:
A damage length measurement system for measuring a length of damage that occurred in an object being measured, the system comprising: an oscillator that applies an ultrasonic vibration to the object; a plurality of vibration detection sensors at mutually different positions that detect a vibration wave that propagates through the object from the oscillator; and a measurement apparatus that controls the vibration of the oscillator, and analyzes the vibration wave that was detected by the vibration detection sensors by means of processing detected signals from the vibration detection sensors, wherein the measurement apparatus is constructed such that it: (1) executes a process of calculating arrival times of maximum peaks of the vibration wave detected by at least two vibration detection sensors that are selected from the plurality of vibration detection sensors, and calculating a difference between the arrival times; (2) executes a process, following process (1), of determining whether or not the difference between the selected sensors is within a set reference range considering a vibration propagation time between the at least two vibration sensors; (3) executes a process, when it is determined in process (2) that the difference is within the reference range, of calculating the damage length based on a delay time with respect to a calibration value of the arrival times of the maximum peaks; (4) executes a process, when it is determined in process (2) that the difference is not within the reference range, of detecting a peak that arrived before the maximum peak and has a specified vibration amplitude or greater for at least one of the at least two vibration detection sensors related to the difference; and (5) executes a process, when the peak having the specified vibration amplitude or greater is detected in process (4), of replacing the arrival time of the maximum peak with the arrival time of that peak and calculating the difference in the process (1), and then executing processes (2) and (3).