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Curing residual strain monitoring in different layer of Gr/epoxy laminated composites using embedded optical fiber Bragg grating sensors

The Gr/Epoxy laminated composite materials have high specific stiffness and strength for applications in the aerospace and industries. It is important to monitor the curing residual stress to ensure the reliability of composite materials. Fiber Bragg Grating (FBG) sensors are small and compatible with polymeric materials so that they can be easily embedded into the internal sensing site of a composite structure without introducing significant defections. This study embedded 4 FBGs into different laminae of composite materials to monitor the internal residual strain during the curing process. The curing residual strain was assessed via changes in the shape of the optical spectra, intensity attenuation and shifts in wavelengths of FBGs. Utilizing this approach we can monitor curing residual strains in different layers of the composite during the curing process.