광섬유센서를 삽입한 복합재료 적층판의 기계적 특성 및 손상검출에 관한 연구

Abstract

The effect of optical fiber embedded in composite structures to monitor the internal deformation and damage on the mechanical properties was investigated. Unidirectional specimens and crossply specimens containing one or three optical fiber sensors were fabricated and uniaxial tension tests were performed. Testing data of stiffness. Poisson``s ratio and strength of these specimens were compared to those of specimens without embedded optical fiber. All specimens were fabricated using transparent Glass/Epoxy prepares since the occurrence of damage of specimens and bleeding of laser signal due to the damage of optical fiber sensor can be observed visually and directly. The optical fibers were embedded at the neutral surface parallel to the loading axis. Stress and strain concentration which can arise around the optical fiber embedded in the crossply specimens were investigated with FEM analysis. and matrix crack initiation and growth behavior was also observed. Finally. the relationship between the fracture of optical fiber and damage of specimens was discussed. From the results showing that stiffness. Poisson``s ratio and strength values of specimens with different number of embedded optical fibers were distributed within the 10% deviation, it can be said that small quantities of optical fiber embedded do not have significant effect on the mechanical characteristics and matrix crack initiation and growth behavior of composite laminates. As for crossply specimens. the fracture of optical fiber arise near the time of saturation of matrix crack density. However. the fracture of optical fiber at the unidirectional specimens arise before observing macroscopic damage of specimens