Some contributions to the homogenization of macroscopically isotropic composites

The development of the homogenization models and solutions, either analytic or numerical, is a difficult task. Due to the integral nature of equations, the result has a good chance to fall within the theoretical bounds and as long as it is there - there might be no indication for any mistake. The difficulty of the homogenization stems not from the involved mathematical concepts, but rather from the little, to at times, no difference between something correct and something that just happens to look plausible. In this work it is argued that the Hashin-Shtrikman expressions are not bounds, but rather boundaries of the solution (hyper)surface. It is also shown that the well known Hill condition is not a necessary ingredient for the homogenization. Using a few homogenization concepts, a complete system of equations describing the macroscopic behavior of the heterogeneous materials has been derived. This system possesses a simple solution in the isotropic case.