In recent years, enhanced thermal conductive properties of polymer composites filled with reduced graphene oxide (rGO) have been studied for diverse applications. However, rGO fillers tend to form aggregates, making it difficult to reach the maximum enhancement through the use of rGO. Experiments have shown that the hydrogen bond between rGO and montmorillonite (MMT) can lead to a stable dispersion of rGO with the result of improving the effective thermal conductivity (ETC) of the composite. However, the mechanisms of this phenomenon are not yet well known. In this work, a micromechanics-based method is proposed to provide an analytical expression of the ETC of rGO/MMT/polymer composites. The predictions are in good agreement with the experimental data, demonstrating the effectiveness of the proposed framework. Also, the effect of the orientation of the fillers is investigated, which useful to determine the optimal orientation and filling ratio to meet various requirements in the material performance design and preparation of rGO/MMT/polymer composites.

Particulate composites are one of the widely used materials in producing numerous state-of-the-art components in biomedical, automobile, aerospace including defence technology. Variety of modelling techniques have been adopted in the past to model mechanical behaviour of particulate composites. Due to their favourable properties, particle-based methods provide a convenient platform to model failure or fracture of these composites. Smooth particle hydrodynamics (SPH) is one of such methods which demonstrate excellent potential for modelling failure or fracture of particulate composites in a Lagrangian setting. One of the major challenges in using SPH method for modelling composite materials depends on accurate and efficient way to treat interface and boundary conditions. In this paper, a master-slave method based multi-freedom constraints is proposed to impose essential boundary conditions and interfacial displacement constraints in modelling mechanical behaviour of composite materials using SPH method. The proposed methodology enforces the above constraints more accurately and requires only smaller condition number for system stiffness matrix than the procedures based on typical penalty function approach. A minimum cut-off value-based error criteria is employed to improve the computational efficiency of the proposed methodology. In addition, the proposed method is further enhanced by adopting a modified numerical interpolation scheme along the boundary to increase the accuracy and computational efficiency. The numerical examples demonstrate that the proposed master-slave approach yields better accuracy in enforcing displacement constraints and requires approximately the same computational time as that of penalty method. (C) 2020 China Ordnance Society. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co.