Ultrasensitive embedded sensor for composite joints based on a highly aligned carbon nanotube web

摘要

Herein, we present a novel approach for damage sensing in adhesively bonded joints using a carbon nanotube single layer web (CNT-SLW) which marks a significant departure from the approach of dispersing CNTs within epoxy resins. In this work, a very thin, highly aligned CNT-SLW (densified thickness similar to 50 nm) with aerial density of 2.0 mg/cm(2) was horizontally drawn from a vertically aligned CNT forest, positioned over an adhesive film, which was, in turn, placed between two non-conductive composite adherents. This was followed by the application of heat and pressure to cure the adhesive. These joints were subjected to quasi-static and cyclic loading to investigate the damage sensing performance of a CNT-SLW. The CNT-SLW sensor, placed parallel to the load direction, exhibits remarkably high cyclic stability as well as exceptionally high sensitivity to damage initiation and accumulation. The resistance increase (Delta R/R-o% similar to 1633%) is significantly higher than that of adhesive sensors with dispersed CNTs/graphene reported in the literature. Morphological studies help to explain the sensing mechanism through interactions of the CNT-SLW with the evolution of micro-cracks. These results demonstrate the potential of macroscopic architectures of CNTs, with controlled orientation, for the development of high performance structural health monitoring (SHM) systems for damage detection. (C) 2019 Elsevier Ltd. All rights reserved.