Characterization of a FBG strain gage array embedded in composite structure

In recent researches, fiber Bragg grating (FBG) is proven the most promising fiber optic strain sensor upon its elaborate strain sensibility. Numerous efforts have been done in realizing practical FBG strain gage systems, either mounted on the surface, or integrated within the structure. Fiber reinforced composite materials are always regarded as the nominated candidate to embed FBG sensors upon the fact that, fiber reinforced filamentary topology enables the integration and effectively protects sensors from hostile attack, therefore a fiber optic smart structure is achievable. However, one must recognize that embedded FBG fibers are foreign entities to host structures, mechanical mismatches may eventually lead to alteration on sensors' responsive behaviours, and measurand interpretation becomes complicated. This work reports a set of experiments on an orthogonal FBG array embedded in graphite/epoxy composite structures. Recurring to corresponding surface mounted resistance strain gages, the authors tend to provide a comprehensive investigation on strain-optic behaviours of embedded FBG sensors, and a quantitative discussion on inevitable deviations of the sensors when used as buried strain gages. (c) 2005 Elsevier B.V. All rights reserved.