  Short-fiber-reinforced polymer composites are increasingly used in
engineering applications and industrial products owing to their unique
combination of superior mechanical properties, and relatively easy and low cost
manufacturing process. The mechanical behavior of short carbon nanotube (CNT)
polymer composites, however, remains poorly understood due to size and time
limitations of experiments and atomistic simulations. To address this issue,
the tensile fracture behavior of short CNT reinforced poly (methyl
methacrylate) (PMMA) matrix composites is investigated using a coarse-grained
(CG) model. The reliability of the CG model is demonstrated by reproducing
experimental results on the stress-stain behavior of the polymer material. The
effect of the nanotube weight fraction on the mechanical properties, i.e. the
Young's modulus, yield strength,tensile strength and critical strain, of the
CNT/polymer composites is studied in detail. The dependence of the mechanical
properties of the composites on the orientation and length-to-diameter aspect
ratio of nanotube reinforcements is also examined.
