Determination of effective thermomechanical parameters of a mixture of two elastothermoviscoplastic constituents

We analyze plane strain deformations of a representative volume element (RVE) to evaluate effective thermophysical parameters of a particulate composite comprised of two perfectly bonded heat conducting elasto-thermo-visco-plastic constituents. It is assumed that the composite is also isotropic and its response elasto-thermo-visco-plastic. Effective values of material parameters so computed are compared with those obtained from either existing micromechanics models or the rule of mixtures or both. It is found that values computed from the rule of mixtures differ at most by 10% from those obtained by using the RVE. Effective stress versus effective strain curves obtained by analyzing simple shearing and axisymmetric deformations of the RVE and of the homogenized material, and also those obtained in plane strain deformations involving loading/unloading/reloading are found to be very close to each other. Time histories of the effective plastic strain at two neighboring points, one in each constituent, are quite different. The effective stress computed by the rule of mixtures from the average effective stress in each constituent and its volume fraction is very close to that obtained from surface tractions acting on the specimen boundaries. The average effective stress in a constituent is computed from the effective plastic strain averaged over that constituent. This also holds for a composite comprised of three constituents.