Cure Monitoring of Composite Laminates Using Fiber Optic Sensors

Abstract

In this paper, we present the simultaneous measurement of the strain and temperature during cures of various composite laminates using fiber optic sensors. Fiber Bragg grating/extrinsic Fabry-Perot interferometric (FBG/EFPI) hybrid sensors were used to measure those measurands. The characteristic matrix of the hybrid sensor is derived analytically and measurements can be done without sensor calibration experiments. For the fabrication of the three types of graphite/epoxy composite laminate, two FBG/EFPI hybrid sensors were embedded in each composite laminate in two mutually perpendicular different directions. We performed the real time measurement of fabrication strains and temperatures at two points within the composite laminates during cure process in an autoclave. Through these experiments, FBG/EFPI sensors are proven to be an efficient choice for smart monitoring of composite structures.