Numerical evaluation of effective elastic properties of graphite fiber towimpregnated by polymer matrix

Homogenized elastic material properties are found for a fibrous graphite-ep oxy composite system with fibers randomly distributed within a transverse p lane section of the composite aggregate using the finite element method. To enhance efficiency of the numerical analysis the real microstructure is re placed by a material representative volume element, represented here by a p eriodic unit cell consisting of a small number of particles, which statisti cally resembles the actual composite. Such a unit cell is derived from 3 si mple optimization procedure formulated in terms of various statistical desc riptors characterizing the microstructure of the random medium. In the pres ent approach the two-point probability and the second order intensity funct ions are employed. The upper bound on the macroscopic elastic stiffnesses t hen follows from the principle of minimum potential energy. The Finite Elem ent Method (FEM) is used to carry out the numerical analysis. Results deriv ed herein confirm applicability of the present approach and suggest that th e unit cell, which effectively exploits the knowledge of the material's sta tistics of the composite, is more reliable then the one constructed simply as a cut of a small part of the real microstructure. (C) 2000 Elsevier Scie nce Ltd. All rights reserved.