Graphene and carbon nanotube-based high-sensitive film sensors for in-situ monitoring out-of-plane shear damage of epoxy composites

Graphene (GN) and carbon nanotube (CNT) have already been explored their potential crack-monitoring abilities in the field of composite materials, but a relatively low sensitivity to shear damage is still a practical problem. This work aims to improve the monitoring sensitivity to out-of-plane shear damage by constructing hybrid GN/ CNT film sensors with a GN weight loading of 0-10%. The prepared GN/CNT sensors are integrated into epoxy composites and both quasi-static and cyclic shear loads are carried out. It is found from quasi-static testing that once the out-of-plane shear damage initiates, relative electrical resistance variation suddenly jumps about 34-191% from the GN/CNT film sensors. Also, the sensitivity coefficient in the crack growth stage could reach 124-684. Namely, the GN/CNT sensors show high monitoring sensitivity to the initiation and growth of out-of -plane shear damage. Moreover, results from cyclic loading further reveal that the GN/CNT sensors possess stable sensitivity to the shear deformation and damage. Meanwhile, similar response trends from an acoustic emission sensor prove the monitoring reliability of the GN/CNT film sensors. The obtained high sensitivity demonstrates that the GN/CNT hybrid film sensors are prospective in the field of structural health monitoring of composite materials.

Automated summary

This study aims to improve the monitoring sensitivity to out-of-plane shear damage by constructing hybrid GN/CNT film sensors, which show high sensitivity to the initiation and growth of shear damage, as well as stable sensitivity to shear deformation and damage under cyclic loading. The obtained high sensitivity demonstrates the prospective application of GN/CNT hybrid film sensors in structural health monitoring of composite materials.