*J.Appl.Mech.* **69**, 489-497, 2002

### A LOCAL THEORY OF ELASTOPLASTIC DEFORMATION

OF TWO-PHASE METAL MATRIX RANDOM STRUCTURE COMPOSITES

V.A. Buryachenko¹, F.G. Rammerstorfer ² and
A.F. Plankensteiner³

¹Air Force Research Laboratory, Materials Directorate,

AFRL/MLBC, Wright-Patterson AFB, Dayton, OH

²Institute of Lightweight Structures and Aerospace
Engineering,

TU Wien,
Vienna, Austria

³Plansee AG, Reutte, Austria

**Abstract** - A two-phase material is considered, which consists of a
homogeneous elastoplastic matrix containing a homogeneous statistically uniform
random set of ellipsoidal inclusions with the same form, orientation, and
mechanical properties.
The multiparticle effective field method (used in this paper) in the original
form assumes constant plastic strains in the matrix.
This assumption is replaced by the following micromechanical model:
Each inclusion consists of an elastic core and a thin coating.
The mechanical properties of both the matrix and the coating are the same but
with different plastic strains.
Homogeneous plastic strains are assumed inside the matrix and in each of
separate subdomains of the coating.
A general theory of plasticity is developed for arbitrary loading based on
incremental elastoplastic analysis.
The consideration of inhomogeneity of plastic strains in the coating enables to
obtain some principally new effects of elastoplastic deformation.

(hjb,020722)