Numerical Estimation of the Mechanical Properties of CNT- reinforcing Composites

Carbon nanotubes (CNTs) possess excellent mechanical properties, such as high stiffness, strength, resilience etc., and may become an ideal reinforcing material for the development of nanocomposites. In this paper, we establish a finite element model of the volume representative element (RVE) for CNT-reinforcing composites and evaluate their mechanical properties based on the Equivalent Homogeneous material concept. Cases considered in this study include two different CNT-reinforcing types, i.e. long and short CNTs embedded in a matrix as well as in a carbon fiber (CF) composite. For verification, the obtained results are compared with those provided by the other approaches, such as Rule of Mixture and Eshelby’s Equivalent Inclusion Theory, and good agreement in most cases shows that the present approach is an effective tool to characterize CNT-reinforcing composites. Moreover, we investigate the obtained mechanical properties and find that the axial Young’s modulus of a matrix can increase as large as 2.3 times and 45% with only 1% weight fraction of long and short CNT addition respectively. However, for adding CNTs to CF composite, the reinforcement in axial Young’s modulus is not as good as in the matrix, but the transverse Young’s modulus and shear modulus can still increase significantly with a small amount of CNT addition. Especially for random and uniform distribution type of the adding CNTs, which demonstrate the best reinforcement effect in the transverse Young’s modulus and shear modulus among the present studied cases, the two moduli can be raised by about 33% and 39% respectively.