Creep of metal-matrix composites with elastic fibers .1. Continuous aligned fibers

Three-dimensional constitutive equations are developed for the time-dependent (transient) creep behavior of metal-matrix composites reinforced by continuous elastic fibers. The composite model is developed in two steps: (i) one in which shear loads relative to the fibers are applied and the response is matrix-dominated, and (ii) another in which the composite is subjected to axisymmetric loads relative to the fibers and the response is fiber-dominated. The predictions of the model are compared with the solutions of a number of 'unit cell' problems; periodic boundary conditions, consistent with the requirements of homogenization theory, are imposed on the unit cell, and the solutions are obtained by using the finite element method. A method for the numerical integration of the developed constitutive equations is presented and the material model is implemented in a general-purpose finite element program. (C) 1997 Elsevier Science Ltd.