• Title, Summary, Keyword: 페브리-패로 간섭계

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Measurement of Dynamic Strain of Structures Using a Gold-deposited EFPI (금 증착된 광섬유 외부 패브리-페로 간섭( EFPI ) 센서를 이용한 구조물의 동적 변형률 측정)

  • Kim, Dae-Hyeon;Gang, Hyeon-Gyu;Hong, Chang-Seon;Kim, Cheon-Gon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.30 no.2
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    • pp.52-58
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    • 2002
  • Measurment of dynamic strain is important to monitor structural integrity. In this paper, the new type of EFPI is proposed to measure the dynamic strain. The second reflecting surface of fiber in this new sensor is deposited gold on to increase its reflectivity. So, it is called the gold-deposited EFPI (G-EFPI) in this paper. In order to explain the principle of measurement of the dynamic strain, two models for the loss of intensity are proposed and an experiment is performed. If a cavity between two reflecting surface increases, the loss of the light that passes through the cavity increases, causing a subsequent decrease in the output intensity of the sensor. Conversely, if the cavity decreases, the amount of loss decreases and the output intensity increases. Also the optimal length of the cavity is proposed to manufacture the G-EFPI with high sensitivity. Finally, the dynamic strainof a composite specimen was measured successfully using the G-EFPI.

Real-time Failure Detection of Composite Structures Using Optical Fiber Sensors (광섬유 센서를 이용한 복합재 구조물의 실시간 파손감지)

  • 방형준;강현규;류치영;김대현;강동훈;홍창선;김천곤
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.128-133
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    • 2000
  • The objective of this research is to develop real-time failure detection techniques for damage assessment of composite materials using optical fiber sensors. Signals from matrix cracking or fiber fracture in composite laminates are treated by signal processing unit in real-time. This paper describes the implementation of time-frequency analysis such as the Short Time Fourier Transform(STFT) to determine the time of occurrence of failure. In order to verify the performance of the optical fiber sensor for stress wave detection, we performed pencil break test with EFPI sensor and compared it with that of PZT. The EFPI sensor was embedded in composite beam to sense the failure signals and a tensile test was performed. The signals of the fiber optic sensor when damage occurred were characterized using STFT and wavelet transform. Failure detection system detected the moment of failure accurately and showed good sensitivity with the infinitesimal failure signal.

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