Micromechanical prediction of elastic-plastic behavior of a short fiber or particle reinforced composite

Homogenized stresses of the fiber and matrix in a representative volume element (AVE) of a short-fiber or particle reinforced composite are calculated by extended Bridging Model. A matrix plasticity induced nonlinear deformation is predicted. All of the formulae are analytical and in closed-form, and only the original fiber and matrix properties are required. The homogenized stresses of the matrix must be converted into true values before used to determine an effective property of the composite. The true stress under a longitudinal tension is defined and evaluated in the first time. A geometric model is proposed to determine the matrix-to-fiber length ratio in the RVE. The effect of fiber orientations is considered in obtaining the composite properties from the RVEs. The predicted nonlinear responses are verified against the available experimental data of different fiber contents and fiber aspect ratios, showing that the true stress concept is critical for a reasonable prediction.