Predicting the macroscopic behaviour of metal-matrix composites embedding an interphase

A numerical model previously developed by Taliercio is applied to the prediction of the macroscopic nonlinear behaviour of unidirectional metal-matrix composites (MMCs), considering the presence of an interphase region between the fibres and the matrix. Special 2D finite elements are formulated, capable of describing Generalized Plane Strain conditions for a representative unit cell of the composite, that is, 3D deformation modes invariant along the fibre axis. Periodicity conditions at the boundary of the cell complete the kinematic formulation. The three phases of the composite are supposed to be elastic-perfectly plastic and to conform with J2-plasticity. Some numerical applications are carried out to investigate the influence of the interphase material on the macroscopic strength of the composite under elementary stress states.