A simple criterion to evaluate the degree of damage in composite materials after sudden impact loads by exploiting the MWCNTs piezoresistive property

Composite materials are widely used in various important applications due to their good engineering properties. However, these properties can be reduced by sudden impact loading effects. In this work, a new approach for condition monitoring was proposed, which unlike other efforts, does not require additional sensors, but instead is carried out directly by exploiting of the multi-wall carbon nanotubes (MWCNTs) piezoresistive property. An epoxy resin was modified with different concentrations of MWCNTs in order to fabricate a nanocomposite material with high electrical conductivity. These nanocomposites were used as a matrix for a glass fibre composite to fabricate MWCNTs/glass/epoxy (MWCNTs-GE) nanocomposites. Scanning electron microscopy (SEM) and Raman spectroscopy were used to investigate the presence of the MWCNTs and their interaction with the matrix. Mechanical, electrical, damage factor and damage sensitivity properties were examined experimentally and statistically as the specimens were subjected to different levels of impact energies. The results showed that the changes in electrical resistance of specimens increased with increasing the impact of energy. Moreover, the MWCNTs-GE nanocomposite specimens containing a high concentration of MWCNTs showed a lower damage factor and a lower damage sensitivity under all impact energies levels. Therefore, the results given in this study have shown that it is possible to correlate between the degree of damages incurred by the impact load with the changes in electrical resistance of the MWCNTs-GE nanocomposites both during, and after, impact. Crown Copyright (C) 2019 Published by Elsevier Ltd. All rights reserved.