DILUTE ESTIMATES OF INELASTIC DEFORMATION IN METAL-MATRIX COMPOSITES

A micromechanical model is utilized to estimate the elastic-plastic de formation characteristics of a discontinuously reinforced composite co nsisting of an elastic-plastic matrix material reinforced with a dilut e concentration of axisymmetric elastic inclusions. By neglecting inte ractions between neighbouring inclusions, the composite is modeled by considering the problem of a single inclusion embedded in an infinite matrix material. The matrix material is assumed to obey J(2) flow theo ry with isotropic hardening. The finite element method is utilized to solve the nonlinear boundary value problem. Results are presented whic h illustrate the effect of reinforcement geometry on the magnitude and distribution of local matrix field quantities, both prior and subsequ ent to local matrix yielding. The effect of matrix yielding on the dis tribution of axial stress in the inclusion is also examined. A volume averaging scheme is then employed to obtain dilute estimates for the m acroscopic response. Results showing the effect of reinforcement shape and volume fraction on the predicted stress-strain response of the co mposite are presented. It is shown that the reinforcement shape can ha ve a significant effect on the effective properties of the composite m aterial.