Composites Research

The Korean Society for Composite Materials (한국복합재료학회)
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Strain Transmission Ratio of a Distributed Optical Fiber Sensor with a Coating Layer

코팅된 분포형 광섬유 센서의 변형률 전달률

  • Yoon, S.Y. (Department of Mechanical System Engineering, Chonbuk National University) ;
  • Kown, I.B. (Center for Safety Measurement, Korea Research Institute of Standard and Science) ;
  • Yu, H.S. (Department of Mechanical System Engineering, Chonbuk National University) ;
  • Kim, E. (Automotive Hi-Technology Research Center and LANL-CBNU Engineering Institute-Korea, Chonbuk National University & Department of Mechanical System Engineering, Chonbuk National University)
  • Received : 2018.07.26
  • Accepted : 2018.11.16
  • Published : 2018.12.31
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Abstract

We investigate strain transmissions of a surface bonded distributed optical fiber sensor considering strain variation according to positions. We first derive a strain transmission ratio depending on a wavelength of a strain distribution of the host structure from an analysis model. The strain transmission ratio is compared with numerical results obtained from the finite element method using ABAQUS. We find that the analytical results agree well with the numerical results. The strain transmission ratio is a function of a wavelength, i.e. the strain transmission ratio decreases (increases) as the wavelength of the host strain decreases (increases). Therefore, if an arbitrary strain distribution containing various wavelengths is given to a host structure, a distorted strain distribution will be observed in the distributed optical fiber sensor compare to that of the host structure, because each wavelength shows different strain transmission ratio. The strain transmission ratio derived in this study will be useful for accurately identifying the host strain distribution based on the signal of a distributed optical fiber sensor.

본 연구에서는 구조물에 부착된 분포형 광섬유 센서의 변형률을 정밀하게 분석하기 위해 위치에 따른 변형률의 변화를 고려하여 광섬유 센서의 변형률 전달률을 분석하였다. 표면에 부착된 코팅된 광섬유 센서의 모델로부터 해석적으로 광섬유 센서의 변형률 전달률을 유도하였으며, 유도된 변형률 전달률은 유한요소해석을 통해 수치적으로 해석한 결과와 비교 검증하였다. 주 구조물의 변형률이 동일한 파장을 가지며 변하는 경우 센서의 변형률 전달률은 위치에 따라 동일한 값을 보였으며, 따라서 변형률 분포의 형상은 왜곡되지 않는다. 하지만 위치에 따라 변형률 파장이 변하면 변형률의 전달률이 위치에 따라 달라져 변형률 분포의 형상이 왜곡될 수 있음을 확인하였다. 본 연구를 통해 얻어진 파장에 따른 변형률 전달률은 분포형 광섬유 센서로부터 주 구조물의 변형률 분포를 정밀하게 추정하는데 유용하게 사용될 것으로 기대된다.

Keywords

BHJRB9_2018_v31n6_429_f0001.png 이미지

Fig. 1. Analysis model of an attached OFS on the surface of a structure

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Fig. 2. FEA result of an attached OFS (a) Cross section of the model (b) Comparison between the host strain and the OFS strain (c) Strain transmission ratio

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Fig. 3. Effect of wavelength on strain transmission. (a) Applied stress distribution on the host structure (b) Strain transmission ratios of the four models

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Fig. 4. Comparison of strain transmission ratios between analytical results and FEA results

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Fig. 5. Strain transmission (a) Displacement distribution of a host structure (b) Comparison of host strain and OFS strain (c) Wavenumber response of host and OFS (d) Strain transmission ratio of an attached OFS

Table 1. Dimensions and mechanical properties of theoretical model [13]

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