Multiscale nanocomposites and laminates reinforced by carbon nanotubes and fibres.

Abstract

The addition of nanomaterials to conventional composites as reinforcement results in a new generation of composites, namely, multiscale composites. Multiscale composites comprise of reinforcements from two or more different length scales such as macro, micro and nano hence the name multiscale. Developing a computational modelling approach which analyses the flexural response of nanocomposites at the nanoscale, which is not restricted by time scales, would benefit future studies in the field of nanotechnology. The dissertation details the analysis of carbon nanotube reinforced composites. The key focus areas include micromechanical modelling of both two and three phase nanocomposites along with their applications to structural elements. Furthermore, the flexural behaviour of a simply supported hybrid plate element subjected to a uniform transverse pressure is analysed under various conditions. Firstly, both carbon and glass fibre reinforced composites are investigated along with a nanomaterial such as carbon nanotubes (CNT) to form a multiscale epoxy composite. Modelling techniques such as Mori-Tanaka and Halpin-Tsai approaches are furthered in order to investigate the mechanical properties of both two-phase and three-phase composites. The results obtained from these models are compared to theoretical and experimental results available in the literature. Secondly, the material properties obtained are then used to investigate the bending behaviour of a CNT/fibre/polymer cross-ply laminate by incorporating micromechanical modelling techniques with structural mechanics. Numerical results are then obtained and used to study the effect of various problem parameters such as agglomeration, different fibre reinforcements, material layup and nanotube diameter. The numerical results given in this study provides a quantitative analysis of the effects of different types of CNT parameters, fibre reinforcements and the volume fractions on the static behaviour of laminated composites.