An embedded non-intrusive graphene/epoxy broadband nanocomposite sensor co-cured with GFRP for in situ structural health monitoring

Abstract

Glass fiber-reinforced polymer (GFRP) composites degrade continuously through service, entailing effective health monitoring to ensure structural integrity. We develop a new type of GFRP structure, with the embedded non-intrusive sensors for in situ structural health monitoring (SHM). Piezoresistive nanocomposite sensors – a pre-cured hybrid of graphene nanoplatelet (GNP) and epoxy, are molded in the second lamina of GFRP prepreg with epoxy matrix during lay-up to laminate process and then co-cured with GFRP composite, keeping the continuity at the interface between the composite. The GNP/epoxy sensor successfully captures the structural response from static strain to a high frequency ultrasonic wave up to 600 kHz with a gauge factor up to 26, which is the first ever nonintrusive GNP/epoxy piezoresistive sensor with an ultra-wide frequency response to mechanical deformation. Furthermore, the mechanical properties of host composite show negligible signs of intrusion testified with tensile and bending tests. GFRP with embedded sensor features merits of high strength from GFRP as well as high-sensitivity sensing capability from the nanocomposite sensors, opening up a new avenue to in situ health monitoring of composites.