MICROMECHANICS AND EFFECTIVE ELASTOPLASTIC BEHAVIOR OF 2-PHASE METAL-MATRIX COMPOSITES

A micromechanical framework is presented to predict effective (Overall) elasto-(visco-)plastic behavior of two-phase partiCle-reinforCed metal matrix comPosites (PRMMC). In particular, the inclusion phase (particle) is assumed to be elastic and the matrix material is elasto- (visco-) plastic. Emanating from Ju and Chen's (1994a, b) work on effective elastic properties of composites containing many randomly dispersed inhomogeneities, effective elastoplastic deformations and responses of PRMMC are estimated by means of the ''effective Yield criterion'' derived micromechanicallY by considering effects due to elastic Particles embedded in the elastoplastic matrix. The matrix material is elastic or plastic, depending on local stress and deformation, and obeys general plastic flow rule and hardening law. Arbitrary (general) loadings and unloadings are permitted in our framework through the elastic predictor-plastic corrector two-step operator splitting methodology. The proposed combined micromechanical and computational approach allows us to estimate overall elastoplastic responses of PRMMCs by accounting for the microstructural information (such as the spatial distribution and micro-geometry of particles), elastic properties of constituent phases, and the plastic behavior of the matrix-only materials. Comparison between our theoretical predictions and experimental data on uniaxial elastoplastic tests for PRMMCs is also presented to illustrate the capability of the proposed framework. A straightforward extension to accommodate viscoplastic matrix material is also presented to further enhance the applicability of the proposed method.