Macro-mechanical material model for fiber reinforced metal matrix composites

The stress-strain behavior of a metal matrix composite reinforced with unid irectional, continuous and periodic fibers is investigated. Three-dimension al micro-mechanical analyses of a unit cell by means of the finite element method and homogenization-localization are carried out. These calculations allow the determination of material behavior of the in-plane, as well as th e fiber directions. The fibers are assumed to be elastic and the matrix ela sto-plastic. The matrix material is governed by a von Mises yield surface, isotropic hardening and an associated flow rule. With the aid of these anal yses, the foundation to a macro-mechanical material model is presented whic h is employed to consider an elementary problem. The model includes an anis otropic yield surface with isotropic hardening and an associated flow rule. A beam in bending containing square fibers under plane strain conditions i s analyzed by means of the model. Two cases are considered: one in which th e fibers are symmetric with respect to the unit cell and one in which they are rotated by an angle of pi/6 with respect to the horizontal axis. Good a greement is found between the macro-mechanical analyses and full finite ele ment analyses of the beam. The aim here is to develop an initial macro-mech anical material model which can be extended to include more realistic aspec ts of the composite elasto-plastic behavior. As part of this model, a famil y of effective stress-effective plastic strain curves are obtained. An impo rtant aspect of this investigation is the implementation of the homogenizat ion-localization technique for elasto-plastic material behavior of non-symm etric unit cells. (C) 1999 Elsevier Science Ltd. All rights reserved.