Elastic-Plastic Deformation Behaviour of Inhomogeneous Materials Including Polycrystals

Abstract

Elastic-plastic deformation behaviour of inhomogeneous materials such as polycrystals is investigated analytically using a plane geometrical model of inhomogeneous materials and finite element calculation. The deformation behaviour is expressed quantitatively making use of constraint ratio calculated from strain distribution in the model. The change of mean constraint ratio for polycrystals during elastic-plastic deformation is obtained. It is found that deformation proceeds between the conditions under constant strain and under constant stress for the most of the calculated range of plastic strains. When elastic inhomogeneity or anisotropy is present, however, the deformation mode becomes close to the constant strain deformation in the elastic-plastic transition stage. The difference between macroscopic yield of polycrystals and microscopic yield in grains due to the presence of elastic inhomogeneity is also discussed.