Plasticity of particle-reinforced composites with a ductile interphase

A homogenization theory is developed to determine the overall elastoplastic behaviorof a particle-reinforced composite with a ductile interphase. Unlike mostexisting homogenization theories which are primarily concerned with the ordinarytwo-phase composites, the present one is confronted with two ductile phases, withone enclosing the other. The theory is developed with the aid of a linear comparisoncomposite using afield-fluctuation method to calculate an energy-based effectivestress of the ductile phases. In order to examine its accuracy, an exact elasticplasticanalysis under dilatational loading is also developed, and it was foundthat, despite its simplicity, the theory could provide plausible estimates for theoverall behavior of the three-phase composite. The theory is applicable to acomposite system regardless whether the interphase is more ductile or stiffer thanthe matrix, and when the interphase is more ductile, it is shown that even thepresence of a thin layer can have a very significant effect on the plasticity of theoverall composite.