광섬유 센서를 이용한 구조물의 열변형 및 온도 측정

Abstract

Three types of fiber-optic sensors such as EFPI(exhimic Fabry-Perot interferometer), FBG(fiber Bragg grating) and M temperature sensor, have been investigated for measurement of thermal strain and temperature. The EFPI sensor and the FBG strain sensor were used to measure thermal strain. FBG temperature sensor was developed to measure stram-independent temperature by encapsulating a M with a glass capillary tube. First of all, we conducted the calibration test to confirm the performance of FBG temperature sensor by measuring wavelength shift of FBG versus temperature that was measured by K-type thermocouple. Fiber optic sensors were demonstrated by embedding into graphite/epoxy composite laminates and by attaching on an aluminum beam and unsymmetric graphite/epoxy composite laminate. AN the tests were conducted in a thermal chamber with the temperature range from room temperature to 100 U. Results of strain measurements by fiber-optic sensors were compared with that from conventional strain gauge attached on the surface. Since EFPI sensor can not measure the temperature, FBG was used as a strain sensor and the thermocouple as a temperature sensor in the test that measure the strain according to temperature. On the other hand, in test using FBG type sensor FBG strain sensor and FBG temperature sensor, which were connected in one optical line, measured strain and temperature without a thermocouple, respectively. Fiber optic sensors could measure the thermal strain and temperature within 1-5 % error.