748 周波数分散に注目した AE 位置同定の可能性  [in Japanese] AE location estimation based on frequency distribution  [in Japanese]

A new fiber-optic vibration sensor has been developed and applied to structural health monitoring. The sensor is based on a new finding that frequency of light wave transmitted through a bended part of an optical fiber is shifted by vibration at the bended region. A very high sensitivity has been achieved in the extremely wide frequency band. The sensor is applied to detection of AE location based on frequency distribution of elastic wave traveling through the material. AE location can be estimated by analyzing time-lag when two of elastic waves distributed with propagation go through the sensor. The system of the analysis needs a method of Short-Time Fourier Transform called STFT, which makes it possible to analyze spectrum alteration of signals as time passing. The performance of the system is examined experimentally. And the system is useful to structural health monitoring in the very variety of applications.