Impact monitoring of smart composites using stabilized fiber bragg grating sensor system = 안정화된 FBG 센서시스템을 이용한 복합적층판의 충격 모니터링에 관한 연구

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This research focuses on the development of impact damage assessment system of smart composite structures using fiber Bragg grating (FBG) sensors. From the viewpoint of hardware development of an FBG sensor system, research on stabilized a high frequency demodulation technique must be performed in order to constantly maintain the sensitivity of the FBG acoustic sensor. Moreover, a multiplexing scheme for a high-speed demodulation should be developed to improve the system efficiency for the construction of the multipoint AE sensing array of impact damage assessment system for a large structure. In this research, a high frequency detectable multiplexing demodulator using the FFP filter with a narrow free spectral range (FSR) was proposed, which can demodulate the input signals of two FBG sensors simultaneously without the loss of measurable frequency range. In addition, an active stabilization control system was constructed to avoid sensitivity fadeout problems and to maintain the maximum sensitivity of the FBG vibration sensors. In the proposed FBG sensor system, the filtering wavelength of the demodulator is continuously adjusted to the operation point of the FBG spectrum where the slope is the steepest. Because the attenuation of AE signal in composite materials is relatively higher than that of metallic materials and FBG sensor has directional sensitivity variation for the vibration signals of longitudinal mode, it is necessary to develop damage assessment technique less affected by the boundary condition in composite structures. In this research, the damage assessment technique using the sharing percentage of the wavelet detail components was proposed, and a low-velocity impact test was conducted on composite laminates using FBG sensors to confirm the feasibility of the proposed signal processing method. The proposed damage assessment method correctly discriminated the impact damage without being influenced by the signal attenuation and the directivity of th...
Advisors
Kim, Chun-Gonresearcher김천곤researcher
Description
한국과학기술원 : 항공우주공학전공,
Publisher
한국과학기술원
Issue Date
2005
Identifier
249484/325007  / 020015133
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 항공우주공학전공, 2005.8, [ xviii, 163 p. ]

Keywords

damage evaluation; impact monitoring; fiber bragg grating sensor; fiber optic sensor; composites; 복합재료; 손상 평가; 충격 모니터링; 광섬유 브레그 격자 센서; 광섬유 센서

URI
http://hdl.handle.net/10203/26332
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=249484&flag=dissertation
Appears in Collection
AE-Theses_Ph.D.(박사논문)
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