Title: Computational Micromechanics of Clustering and Interphase Effects in Carbon Nanotube Composites

Published in: Mechanics of Advanced Materials and Structures, Volume 14, Issue 4 May 2007 , pages 277 - 294

Authors: Daniel C. Hammerand a; Gary D. Seidel b; Dimitris C. Lagoudas b

Affiliations: a Material Mechanics, Sandia National Laboratories, Albuquerque, New Mexico, USA
b Department of Aerospace Engineering, Texas A&M University, College Station, Texas, USA

Abstract
Computational micromechanical analysis of high-stiffness hollow fiber nanocomposites is performed using the finite element method. The high-stiffness hollow fibers are modeled either directly as isotropic hollow tubes or equivalent transversely isotropic effective solid cylinders with properties computed using a micromechanics based composite cylinders method. Using a representative volume element for clustered high-stiffness hollow fibers embedded in a compliant matrix with the appropriate periodic boundary conditions, the effective elastic properties are obtained from the finite element results. These effective elastic properties are compared to approximate analytical results found using micromechanics methods. The effects of an interphase layer between the high-stiffness hollow fibers and matrix to simulate imperfect load transfer and/or functionalization of the hollow fibers is also investigated and compared to a multi-layer composite cylinders approach. Finally the combined effects of clustering with fiber-matrix interphase regions are studied. The parametric studies performed herein were motivated by and used properties for single-walled carbon nanotubes embedded in an epoxy matrix, and as such are intended to serve as a guide for continuum level representations of such nanocomposites in a multi-scale modelling approach.

Keywords: polymer-matrix composites (PMCs); interphase; clustering; elastic properties; finite element analysis (FEA); nanostructures