Fiber bragg grating sensors' validation for strain and temperature

In this research, the characteristic constants for optical fiber Bragg grating strain sensors were determined for their use in metallic structures. Three different experiments were performed with the purpose of finding the constant relationship between the optical wavelength reflected by the FBG sensor and the strain or temperature incidents in a specific structure. It was established a comparison between the behavior of optical sensors versus electrical sensors used traditionally. From these experiments it was obtained a constant value for temperature values between 20 degrees C and 70 degrees C; and for strain from zero up to 1800 mu epsilon. All measurements were taken in 'in-situ' conditions for tests of metallic structures. The results show a higher speed of response for the optical sensors when compared with electrical resistance strain gauges or thermocouples. Also, fiber Bragg grating sensors show a larger operating range in tensile tests.