In this paper, the simulation of the mechanical behavior of ceramic-metal composite Al / Al2O3 under tension, with a clear view of the internal structure. With the previously proposed algorithm for generating three-dimensional structures, a model the three-dimensional composite with inclusions of irregular shapes. The problem of the mechanical behavior of the composite mesovolume under tension solve the finite difference method. The stress-strain state in various sections mesovolume and evolution of plastic deformation in the matrix in the initial stages of plastic flow. A comparative analysis of the results of two-dimensional calculations staged plane strain and plane stress.