On the processing and testing of FRP composites incorporating fiber optic sensors

The use of the pultrusion process for the manufacture of fiber reinforced polymer (FRP) composites with embedded fiber optic sensors is discussed. The specific application is the use of smart composite reinforcements for strain monitoring in engineering structures. The Bragg Grating and Fabry Perot fiber optic sensors are embedded during the pultrusion of FRP rods and the process induced residual strains are evaluated using these sensors. The behaviour of optic sensors during pultrusion is assessed, and the effect of the embeddment of optical fibers and their surface coatings on the mechanical properties of the composite is investigated Monitoring of the output of embedded fiber optic strain sensors during the pultrusion of composite rods gives a unique view of the formation of residual strains within the pultrusion die itself. To verify the operation of the optic sensors embedded in the smart pultruded tendons, mechanical tests were conducted and the output of the fiber optic sensors was compared to that of an extensometer during quasi-static and cyclic tensile tests.