When boundary conditions are as follows: they are all stress ones

or contain displacement boundary condition but only contain zero-displacement boundary condition on the plastic region’ boundary (with no limitation on stress boundary condition)

Reference [1] obtained important conclusion of elastoplastic stress field. By introducing an elastic body that has the same geometric shape and boundary condition as those of the plastic area of the problem under consideration and making use of the uniqueness theorem of elastic solution

the conclusion of Reference [1] was proved again in this paper.