Int.J.Plast. 7, 781-802, 1991


A 3/D FINITE ELEMENT APPROACH FOR METAL MATRIX COMPOSITES
BASED ON MICROMECHANICAL MODELS

A.J. Svobodnik, H.J. Böhm and F.G. Rammerstorfer

Institute of Lightweight Structures and Aerospace Engineering,
TU Wien, Vienna, Austria


Abstract - Based on analytical considerations by Dvorak and Bahei-el-Din, a 3/D finite element material law has been developed for the elastic-plastic analysis of unidirectional fiber-reinforced metal matrix composites. The material law described in this paper has been implemented in the finite element code ABAQUS via the user subroutine UMAT. A constitutive law is described under the assumption that the fibers are linear-elastic and the matrix is of a von Mises-type with a Prager-Ziegler kinematic hardening rule. The uniaxial effective stress-strain relationship of the matrix in the plastic range is approximated by a Ramberg-Osgood law, a linear hardening rule or a nonhardening rule. Initial yield surfaces of the matrix material and for the fiber reinforced composite are compared to show the effect of reinforcement. Implementation of this material law in a finite element program is shown. Furthermore, the efficiency of substepping schemes and stress corrections for the numerical integration of the elastic-plastic stress-strain relations for anisotropic materials are investigated. The results of uniaxial monotonic tests of a boron/aluminum composite are compared to some finite element analyses based on micromechanical considerations. Furthermore, a compelete 3/D analysis of a tensile test specimen made of a silicon-carbide/aluminum MMC and the analysis of an MMC inlet inserted into a homogeneous material are shown.


(hjb,960626)