The influence of creep deformations on the subsequent plastic flow in a material of rotating cylinde

The influence of creep deformations on the process of plastic flow in a material is studied by using the example of the rotational motion of a cylinder with an inner cavity (a pipe) that has a rigid coating on its outer boundary to prevent radial expansion. The problem is solved within the frameworks of the theory of infinitesimal deformations. The theory of plastic flow with the associated condition of maximum octahedral stresses of von Mises, generalized to the case of viscoplastic flow, is used to describe the plastic properties of the material. The Norton's power law is used to describe the viscous properties. In the plastic flow region, the irreversible deformation rates are composed of plastic deformation rates and creep deformation rates. The dependencies required to determine the rotational speed at which plastic deformation initiates in the cylinder material are derived from the elastic deformation solution. A system of integro-differential equations is compiled to find the displacements and stresses in the cylinder material for the specified rotational speeds and accumulated irreversible deformations. Numerical calculations show that the presence of creep deformations leads to a later initiation of plastic flow, a reduction in plastic deformation rates, and a decrease in the plastic flow influence area.