Abstract

FBG (fiber Bragg Grating) sensor becomes a hotspot in recent researches, based on its numerous advantages, especially it can be easily multiplexed to realize sensor network. A number of networking scenarios have been proposed [1] [2], "orthogonal array" is one of the most convincing solutions, in which wavelength division multiplexed FBG sensors are patterned along a single optical fiber and analogical fibers are orthogonally deployed, so that any randomly oriented ambient change can be analytically monitored along two orthogonal sensors of local intersection. Further, by means of various addressing mechanisms [3], stimulus is positioned. However, detailed characterization of a single orthogonal unit is the essence to model entire network. This work reports a set of experiments on an orthogonal FBG array unit embedded in specific Graphite/Epoxy composite structure. First of all, photoelastic behaviour of identical bare FBG fiber was observed, which is to profile an "ideal" FBG strain gage. Then optimization process was carried out to determine the optimal layout for FBG array embedment, which induces minimum perturbation to both sensors and host structure. After optimized specimens were fabricated, tensile loads were applied to specimens. Recurring to surface mounted resistance strain gages, embedded FBG strain gages are recalibrated and their sensing alterabilities are evaluated. Finally, suspended concerns are discussed and conclusions are drawn upon experimental data. (Abstract shortened by UMI.)