Curvature gauges embedded in composites

It has long been known that the inclusion of fibreoptic strain sensors into composite materials produces adverse effects on both, (i) the composite microstructure and (ii) sensor measurements that become ambiguous. The microstructural disadvantages are probably inevitable whatever the type of the fibreoptic sensor used. However, measurement ambiguities can be eliminated by replacing strain as the traditionally preferred measurand of choice with deformation-curvature as a measurand particularly suitable for evaluation of the loading states of composites. Performance examination of recently developed fibreoptic `curvature gauges' embedded between composite laminate is reported in this paper. Not only that unambiguous measurements were achieved, but environmental noise effects were reduced and an additional design flexibility for reducing the degradation of the overall structural properties has been achieved.