Monitoring of static and vibration responses of laminated composite materials using integrated carbon nanotube fibers

Abstract

Carbon nanotube fibers or yarns (CNTYs) are lightweight, stiff, strong, electrically, and thermally conductive fiber-like materials that exhibit a piezoresistive response and could be integrated in glass-fiber/epoxy laminated composite materials to measure strain and to detect damage. Aiming at extending the scope of previous studies, this work is about the piezoresistive response of CNTY sensors integrated in composite laminates of industrial interest, accounting for interactions between the CNTY and the typical heterogeneous, anisotropic surrounding media, including the effects induced by the curing process of the composite matrix. This study reports experimental results on the mechanical response of laminated composite materials under quasi-static and vibration loading monitored using integrated CNTY sensors. A combination of CNTY sensor configurations and experimental setups were used to monitor the deformation and strains among the various layers of the laminated composites. As the laminated composites were mechanically loaded under quasi-static four-point bending, the CNTY sensors captured instantaneously the deformation as demonstrated by the change in their electrical resistance. Also, as the laminated composites were subjected to sinusoidal loading at specific frequencies, the integrated CNTY sensors were able to capture the loading cycles exactly including durations and peaks. Integrated sensing using CNTYs may offer a highly adaptive, practical, and sensitive structural monitoring method for a variety of applications.