2020 年 46 巻 2 号 p. 62-67
It is difficult to evaluate the initiation and propagation of fatigue cracks in type-3 composite vessels used at hydrogen stations. Therefore, a smart vessel using an optical fiber acoustic emission sensor (OFAES) was developed. The relationship between the winding length of the OFAES, which was wound over the vessel, and the sensitivity of the signal was first studied, and it was confirmed that AE signals could be detected with high sensitivity by winding the OFAES according to half the resonance frequency wavelength of the radial direction of the vessel. Using this result, we then fabricated a smart pressure vessel in which the OFAES was wound in a striped pattern according to the half wavelength over the vessel. The sensitivity of the developed vessel was then compared with that of a commercially available piezoelectric (PZT) sensor by an artificial AE sensor. It was found that the PZT sensor was more sensitive when the sensor distance was closer to the AE source; however, the signal-to-noise ratio of the waveform detected by the PZT sensor decreased owing to higher attenuation as the propagation distance increased. Furthermore, the developed vessel was able to detect AE signals with constant sensitivity and frequency characteristics without depending on the position of the artificial AE source.