Elasto-plastic twisting of a two-layer rod weakened by holes

Under study is the elasto-plastic twisting of a multiply-connected two-layer prismatic rod under the influence of a couple of forces with a given moment. It is assumed that the rod consists of two layers. Either layer has its own elastic properties, but the plastic characteristics of both layers are the same. The contact boundary of the layers is located alongside Axis ох. The lateral boundary of the rod is free from stresses; at the interface, continuous are movements and stresses. Stress components at a point are calculated with the help of contour integrals obtained from the conservation laws, calculated on the lateral boundary and the boundaries of the holes. At those points of the rod where yield stress is achieved — plastic state is present, at the rest of them — elastic. This allows building the boundary between the plastic and elastic areas.