Elastic behavior of CNT-reinforced polymer composites with discontinuities in CNT configurations

A numerical study has been made towards the effective elastic properties estimation of carbon nanotubes and carbon nanotube reinforced composite using finite element modelling (FEM). First, the elastic properties of Carbon nanotube (CNT) were predicted by considering that carbon atoms as nodes and carbon-carbon bonds as beam elements with linear and isotropic behaviour. It was observed that elastic properties of CNT predicted by FE analysis were in good agreement with previous data. Carbon atom vacancy defects were also included to investigate the adverse effect on elastic modulus of SWCNTs. To explore the macroscopic elastic behaviour of CNT in a finite densely packed polymer resin, a representative volume element (RVE) was selected instead of whole composite material in which the polymer resin was modelled as continuum material while CNT as an equivalent long fibre. FE results of RVE manifest that the CNT volume fraction and waviness have significant effect on elastic modulus of CNT reinforced polymer composite. An analytical formulation in terms of elastic properties and waviness ratio was also introduced in this study for waviness analysis. Moreover, the elastic properties of wavy CNT reinforced composite was compared with analytical outcomes. We extended present RVE model to incorporate the effects of CNTs agglomeration on the elastic behaviour of CNT-reinforced polymer composites. It was observed that anticipated elastic results not only depended on the volume fraction of CNTs, but also on the CNTs geometry, waviness and agglomeration.