On the yield strength of a ductile material reinforced with rigid spherical inclusions

A micromechanics model for predicting the mechanical properties of a particulate composite is developed. The reinforcing particles are assumed to be rigid and spherical in shape, while the matrix is elastic-perfectly plastic. The interactions among the inclusions are taken into consideration by Mori-Tanaka's approach. The elastic modulus, Poisson's ratio and yield strength of the composite can be conveniently predicted and systematically investigated. The predictions of the model are discussed and compared with other theories. It is concluded that the yield strength of the composite can be improved by increasing the volume fraction of inclusions for most of loading conditions but not for certain loading paths such as spherical (hydrostatic) stress loading. The open-ended circular cylinder of v. Mises yield surface about the spherical stress axis in the principal stress space for the pure matrix changes to a more complicate yield surface ending at two apexes in the spherical stress axis for the composite.