Composite Structures and Fiber Optic Sensor Technology

초록

Composite materials are widely used for aircrafts, satellites, and many other structures due to their good mechanical and thermal characteristics such as high specific stiffness and strength, a low coefficient of thermal expansion, and good heat-resistance. Because of those advantages, their applications are recently expanded to the fields of civil engineering, especially to the repair and maintenance of large structures such as bridges and tunnels including infra-structures. Fiber Bragg grating (FBG) sensors are being studied more actively than any of other fiber optic sensors because of their good multiplexing capabilities. As FBG sensors can be embedded into composite materials, many researches focused on the application of FBG sensors to composites by embedding have been conducted through many application fields. However, there are many limitations on the embedding of FBG sensors into composite materials due to possible problems on peak signals of FBG sensors caused by birefringence or internal strain gradient. In this study, the signal characteristics of reflected spectra of FBG sensors were verified under strain gradients and the correlation between the grating length of FBG sensors and strain gradients were investigated quantitatively.