Multi-Phase Micromechanical Modeling of Fiber/Matrix Debonding Effects on the Elastoviscoplastic Behavior of General Unidirectional Metal Matrix Composites

The elastoviscoplastic behavior of metal matrix composites with various fiber aspect ratios subjected to multi-axial loading is studied by a 3D time-dependent micromechanical model in the presence of interfacial damage. The representative volume element of the composites consists of three phases, fiber, matrix and fiber/matrix interphase. The effects of thermal residual stresses induced from the manufacturing process are included in the analysis. The fiber and interphase are assumed to be elastic, while the matrix exhibits elastic-viscoplastic behavior with isotropic hardening. The Bodner-Partom viscoplatic theory is used to model the time dependent inelastic behavior of the matrix. The Needleman model is employed to analysis interphase damage. While predictions based on undamaged interphase are far from the reality, the predicted thermomechanical behavior including interphase damage and thermal residual stresses demonstrate very good agreement with experimental data.