Overall plasticity of micropolar composites with interface effect

Overall property of composite materials depends on particle size while its volume fraction is kept constant. A micromechanical method is proposed to predict the size-dependent plastic property for composite materials, the proposed method takes into account the non-local effect by idealizing the matrix as a micropolar material, and the interface effect between different phases is also considered. A perturbation method for a micropolar composite with the interface effect is established by a rigorous energy equivalent method, it is then used to estimate the average second-order stress/couple stress moment in the local phase. A secant modulus scheme is proposed to predict the overall non-linear behavior for a micropolar composite with the interface effect. It is found that the non-local and the interface effects on the size-dependent yielding and strain hardening behavior may be synchronized or desynchronized depending on the nature of the interface. For a hydrostatic loading, it is found that the interface effect has an important influence on the overall yielding of the composite. The instability of the composite induced by interface effect is also discussed.