Structural health monitoring in multiscale composite materials: nanoreinforced epoxy matrices and coated fabrics

The incorporation of graphene nanoplatelets (GNPs) as nanoreinforcement in multiscale composite materials has become increasingly interesting for structural health monitoring. The GNPs create an electrically conductive network through the composite material, which is susceptible to dimensional changes. Additionally, the presence of discontinuities i.e. cracks or delaminations, causes the breakage of the conductive paths. These facts make possible the use of GNPs based multiscale composite materials as self-monitoring systems in structural components. In the present work, two different ways of incorporating GNPs in polymer matrix composite materials are studied: (a) nanoreinforcement of the epoxy matrix and (b) coating of the fabric by a GNPs reinforced sizing. In all the cases, the electrical conductivity of multiscale composite materials increases. While composite materials with nanoreinforced matrices can detect translaminar damage, those with GNPs coated fabrics cannot detect it. In the case of monitoring strain, the sensitivity obtained in composite materials with nanoreinforced matrix is superior because microcavities appear in the vicinities of the GNPs causing a higher increment in the electrical resistance. Nevertheless, composites with GNPs coated fabrics have shown to be more sensitive to fibers breakage.