Micromechanical modeling of stress transfer in carbon nanotube reinforced polymer composites

A micromechanics model is developed for assessing the interfacial shear stress transfer in carbon nanotube reinforced polymer (NRP) composites. The model employs three concentric cylinders, each of a different length, as the representative volume element (RVE). A capped, hollow nanotube is utilized as the innermost cylinder that is completely surrounded by a matrix cylinder, which is, in turn, embedded in a composite cylinder. The atomistic structure of the nanotube is incorporated in the model by determining the Young's modulus of the nanotube using the molecular structural mechanics approach. A continuum-based analysis is performed using the elasticity theory for the axisymmetric RVE problem to obtain an analytical solution for computing the average axial normal stress in the nanotube and the interfacial shear stress across the matrix/nanotube interface. Parametric studies are conducted to illustrate the applications of the present model. The numerical results indicate that using sufficiently long and large nanotubes and a small nanotube volume fraction improves the efficiency of stress transfer in NRP composites. The predictions made by the current model are in favorable agreement with existing analytical, experimental, and computational studies.