An abstract (mathematical) model of a deformable solid, based on the possibility of neglecting, in a number of cases, the elastic strains of the body in comparison with the plastic ones. A real solid can be treated as a rigid-plastic body, if its plastic strains are not limited by the elastic strains of the surrounding parts of the body (for example, when a neck forms in a specimen under tension). Otherwise the plastic deformation is constrained (in a thick-walled tube under internal pressure, for example, the inner part of the tube is in the plastic state while the outer part undergoes elastic strains that limit the magnitude of the plastic strains), and the concept of a rigid-plastic body is not justified.
The rigid-plastic model gives an idealised picture of such properties of materials as plastic flow, hardening, anisotropy and others.
The rigid-plastic model gives an idealised picture of such properties of materials as plastic flow, hardening, anisotropy and others.