Strain monitoring using distributed fiber optic sensors embedded in carbon fiber composites

A distributed fiber optic strain sensor based on Rayleigh backscattering, embedded in a fiber-reinforced polymer composite, has been demonstrated. The optical frequency domain reflectometry (OFDR) technique was used to analyze the backscattered signal. The shift in the Rayleigh backscattered spectrum (RBS) was observed to be linear to the change in strain of the composite material. The sensor (standard single-mode fiber) was embedded between the layers of the composite laminate. A series of tensile loads were applied to the laminate using an Instron testing machine, and the corresponding strain distribution of the laminate was measured. The results show a linear response indicating a seamless integration of the optic fiber in the composite material and a good correlation with the electrical-resistance strain gauge results. In this study, distributed strain measurements in a composite laminate were successfully obtained using an embedded fiber optic sensor.