Hybrid influences of interphase and grain-size on material responses of CNT-reinforced metal matrix composites

In this investigation, a theoretical model is developed to consider the coupled influence of interphase and grain-size of metal on the nonlinear response of CNT-reinforced MMCs. A multiscale theoretical framework based on the energy-based effective strain method and the field fluctuation method is established. The second-order stress moment and dislocation density model are also adopted to predict the entire grain-size dependent stress-strain relations. The energybased effective strain method is proposed to better exhibit the energy stored in the three-phase composites by replaced average-strain. The microstructure variables include volume fraction, moduli of interphase, geometrical size factor, aspect ratio of CNTs, and grain size in metal matrix. The accuracy of the present predictions is verified by some available experimental data. As a result, the proposed model can be used to define the mechanical behavior and make an optimum design of CNT reinforced MMCs as well as advanced engineering composites.