*Continuum Models and Discrete Systems*
(Ed. K.Z.Markov), pp. 140-147, 1996

### ELASTIC-PLASTIC BEHAVIOR OF ELASTICALLY HOMOGENEOUS
MATERIALS WITH A RANDOM FIELD OF INCLUSIONS

V.A. Buryachenko and F.G. Rammerstorfer

Institute of Lightweight Structures and Aerospace
Engineering,

TU Wien,
Vienna, Austria

**Abstract** -
A two-phase material is considered, which consists of a homogeneous
elastic-plastic matrix containing a homogeneous statistically uniform
random set of ellipsoidal elastic-plastic inclusions.
The elastic properties of the matrix and the inclusions are the same,
but the so-called "stress free strains", i.e. the strain contributions
due to temperature loading, phase transformations, and the plastic strains,
fluctuate.
A general theory of the yielding for arbitrary loading (by the macroscopic
stress state and by temperature) is employed.
The realization of an incremental plasticity scheme is based on averaging
over each component of the nonlinear yield criterion.
Usually averaged stresses are used inside each component for this purpose.
In distinction to this usual practice physically consistent assumptions
about the dependence of these functions on the component's values of the
second stress moments are applied.
The application of the proposed theory to the prediction of the
thermomechanical deformation behavior of a model material is shown.

(hjb,960709)