광섬유 A-EFPI 센서를 이용한 직교적층 복합재료의 표피층 및 내부층의 변형률 해석

Strain Analysis in the Skin and Core Layers of Cross-Ply Composite Laminates Using A-EFPI Optical Fiber Sensor

  • 우성충 (한양대학교 기계설계학과 대학원) ;
  • 박래영 ((주)오토리브 만도) ;
  • 최낙삼 (한양대학교 기계정보경영공학부) ;
  • 권일범 (한국표준과학연구원 스마트계측그룹)
  • 발행 : 2004.10.01

초록

유리 섬유 강화 플라스틱 직교적층판의 내부층과 표피층의 길이방향 변형률을 삽입된 절대변형 외부 페브리 페로 간섭 센서를 이용하여 측정하였다. 투과식 광학현미경을 이용하여 삽입된 A-EFPI 센서 주위의 파손거동을 관찰하였다. 시험편 표면부의 변형률 측정을 위해 포일 형식의 스트레인 게이지를 시험편 아래 위 표면부에 부착하였다. 또한 삽입된 A-EFPI 센서로 측정한 내부층과 표피층의 길이방향 변형률 값은 스트레인 게이지로 측정한 시험편 표면의 변형률 값 보다 다소 크게 나타났다. 균일 응력 모델을 기초로 한 3차원 유한요소해석을 통해 실험 결과의 타당성을 확인하였으며 내부층의 큰 변형률은 많은 횡단형 균열의 발생을 야기시켰는데 이로 인해 내부층에 삽입된 광섬유센서의 고장시 변형률이 급격히 낮아졌다.

Longitudinal strains (${\varepsilon}_x$) of the core and skin layers in glass fiber reinforced plastic (GFRP) cross-ply composite laminates have been measured using the embedded optical fiber sensor of absolute extrinsic Fabry-Perot interferometer (A-EFPI). Transmission optical microscopy was used to investigate the damage behavior around the A-EFPI sensor. Foil-type strain gauges bonded on both the upper and lower surfaces were used for the measurement of the surface strains. It was shown that values of ${\varepsilon}_x$ in the interior of the skin layer and the core layer measured by embedded A-EFPI sensor were significantly higher than that of the specimen surface measured by strain gauges. The experimental results agreed well with those from finite element analysis on the basis of uniform stress model. Large strains in the core layer led to the occurrence of many transverse cracks which drastically reduced the strain at failure of optical fiber sensor embedded in the core layer.

키워드

참고문헌

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