Evaluation of the Mechanical Properties of Carbon Nanotube Based Composites by Finite Element Analysis

Carbon nanotubes (CNTs) possess extremely high stiffness, strength and resilience, and may provide ultimate reinforcing materials for the development of nano composites. In this paper, the effective material properties of CNT-based composites are evaluated using a square representative volume element (RVE) based on the continuum mechanics and with the finite element method (FEM). Formulas to extract the effective material constants from solutions for the square RVEs under the axial stretch load is derived based on the elasticity theory. An extended rule of mixtures, based on the strength of materials theory for estimating the effective Young’s modulus in the axial direction of the RVE, is applied for comparisons of FEM results. It has been observed that the addition of the CNTs in a matrix at volume fractions of only about 3.6%, the stiffness of the composite is increased by 33% for long CNT at E E ⁄ 10, whereas there is no much improvement in stiffness has been noticed in case of short CNTS at E E ⁄ 10. Effectiveness of composites is evaluated in terms of various dimensions like thickness, diameter and length of CNT. These results suggest that short CNTs in a matrix may not be as effective as long CNTs in reinforcing a composite.