Health self-monitoring of nano-engineered composite structures with enhanced mechanical and electrical profiles

Inclusion of conductive nanoparticles in conventional fiber-reinforced composites can improve material properties and endow the composites with functionalized capability. In this study, 2D graphene nanoparticles are dispersed in glass fiber/polymer composites to optimize and enhance the morphological characteristics of the composites, and some appealing functions have been achieved. In particular, with a 1 wt.% graphene-enriched epoxy resin, conductivity of the developed composites is enhanced dramatically, and the elastic modulus and ultimate tensile strength are improved circa 30% and 10%, respectively. Notably, with an optimized nano-structure in the resin, the composites feature a semi-conductive property and manifest piezoresistivity, on which basis a quantum tunneling effect in the 2D graphene-formed conductive network is triggered, when elastic disturbance is applied to the composites. Making use of such a unique trait, the developed composites possess a capability to self-perceive broadband signals from static tension, through low-frequency vibration, to high-frequency ultrasonic waves (up to several hundred kilohertz). The acquired signals are further used for structural health monitoring. Experimental validation has demonstrated that the developed composites have enhanced mechanical-electrical properties, along with an innovative capability of health self-monitoring.