Foundations of the Theory of Plasticity

Deformability of solids under the effect of external forces and their capability of perceiving constant or residual (plastic) strains at unloading is called plasticity. There is, however, no unequivocal dependence between stresses and strains arising in the body, which means that it is impossible to find strains in terms of stresses, and vice versa, one cannot determine stresses proceeding from known strains.