High Temperature-measurement Using Fiber Bragg Grating Sensor for SHM Applications on Composites

초록

Fiber-optic sensors, fiber Bragg grating (FBG) sensors in particular, are being widely studied as suitable sensors for improved structural health monitoring (SHM) of composite structures due to many merits. Higher reliability and better flexibility, essential part of those sensors, are highly required in many application fields at high temperature. Thermal sensitivity of FBG can be expressed as a term, ？？f + ？？f, and it is generally considered a constant with the assumption of small temperature changes. However, it does change as the temperature changes, and this does affect the accuracy of measurement. This influence becomes more significant as the temperature increases. This study describes the change of thermal sensitivity of FBG under conditions of ultra-high temperature. In order to measure thermal sensitivity, a thermal test in a heating furnace was performed over a range from room temperature to 500oC. From the test results, it was successfully shown that ？？f + ？？f had a non-linear dependency on temperature.