High-sensitive flexural sensors for health monitoring of composite materials using embedded carbon nanotube (CNT) buckypaper

Abstract

The health monitoring for the service status of the composite materials is particularly crucial, calling for highly sensitive piezoresistive strain sensors. This paper outlined the working mechanisms of CNT buckypaper sensor during loading and releasing processes by analyzing the electrical conduction mechanism of the adjacent CNT and developing the macroscopical and mesoscopic models of CNT electrical networks inside of the bukypaper. The CNT-based nanocomposite specimens underwent monotonic and cyclic flexural loading in low strain range to examine the dynamic stability and durability of the in-situ nano sensor. The different support span configurations were also employed and operated to obtain the recommended application scenarios. The long-term response behavior of the nano sensor was also concluded as three typical phases. The desirable agreement was demonstrated by comparing the responses of ΔR/R0 signals and phenomena of the breakage and propagation of micro cracks and the rearrangement and reconnection of CNT conductive networks within the Scanning electron microscope (SEM) images of the buckypaper. The proposed flexural nano sensor is suitable for potential health monitoring application of composite materials.