▎ 摘　　要

The current paper examines a newly developed model to simulate the strain rate-dependent constitutive equation of graphene/polypropylene nanocomposites. The model is a combination of the Halpin-Tsai micromechanics method and the Goldberg model which is called the strain rate-dependent micromechanics model. First, tensile properties of pure polypropylene are measured experimentally. Then by utilizing the Halpin-Tsai micromechanics method, tensile properties of graphene/polypropylene nanocomposites under static loading conditions are achieved. The obtained properties from the micromechanics method are used by the Goldberg model in order to simulate the strain rate-dependent mechanical behavior of nanocomposites under dynamic loading conditions. The material constants of the Johnson-Cook material model are calculated by the strain rate-dependent micromechanics model. The material constants are used in a material model which is implemented in the explicit finite element code LS-DYNA, to simulate the strain rate strain rate-dependent micromechanics-dependent mechanical behavior of the standard Charpy impact test specimen. Polypropylene reinforced with 0.5, 1.0 and 2.0wt% graphene sheets were prepared via coating polypropylene with graphene particles. Then, by melt blending in a twin-screw extruder followed by an injection molding process, the nanocomposites samples are manufactured. The results revealed that the incorporation of a low amount of graphene caused a good improvement in impact strength of polypropylene. To evaluate the current model, the results are compared with the experimental results of the standard Charpy test specimens. A good agreement between the experimental data and the strain rate-dependent micromechanics model is achieved.