| Co-Investigator(Kenkyū-buntansha) |
KATO Tetuji Graduate school of Engineering. The University of Tokyo, Research Assistant, 大学院・工学系研究科, 助手 (70323540)
KAGEYAMA Kazuro Graduate school of Engineering. The University of Tokyo, Professor, 大学院・工学系研究科, 教授 (50214276)
金原 勲 東京大学, 大学院・工学系研究科, 教授 (50011101)
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| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2001: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2000: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
Fiber-optic sensor has excellent characteristic, for example character of low loss, wide range of frequency, light in weight, fine diameter, no induced current, and mutual directional character. Therefore the sensor provides high potential for applying health monitoring of structures. Aim of this study is whether the fiber-optic sensor has a similar function to the conventional AE sensor. First, some fundamental experiments were performed to detect signals by using fiber-optic sensor. Namely quasi AE wave was entered into a steel plate, and then the signal was detected by the fiber-optic sensor. Influence of filtered frequency range, pasting way and length of the Fiber-optic sensor on the plate, directional sensitivity of propagated signal and so on, were examined. As the result, value of S/N ratio indicated low, but activity of high amplitude signal showed similar to signal of conventional AE sensor. The fiber-optic sensor applied to tensile tests of FRP, then the high amplitude signals emitted during the loading were detected satisfactory.
On the other hand, we had some experiments to examine fundamental performance of a Fiber-optic Laser-Doppler Vibro-meter (FLDV) by using a pole of steel and GFRP, in which elastic waves propagated. Influence of pasting length and pasting direct of fiber-optic sensor on the pole, and change of impact velocity were examined. As the results, FLDV has directional sensitivity, and also has high sensitivity about propagation of elastic wave from the opposite end rather than from end of a light source. It seemed there was no extension and contraction in sensor length, so it might be moving velocity of sensor end when the clastic waves were detected. The signal wave during minus acceleration became to be an attenuation wave
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