Heat Production due to Creep Strains and Wall Viscoplastic Flow in the Plug Material in a Round Pipe under the Action of Variable Pressure Difference

A solution is obtained for the coupled boundary value problem of non-isothermal deformation of a material forming a finite-length plug in a non-deformable round pipe. Under conditions of rigid adhesion to the pipe surface, the material is deformed under the action of a variable pressure drop specified on the end surfaces of the plug. Irreversible deformation is associated with both creep and viscoplastic flow of the material and causes its heating. Additionally, the dependences of the yield strength, viscosity coefficient, and creep parameters of the material on temperature are taken into account. Using the large deformation model, the processes of creep and viscoplastic flow with increasing and constant pressure drop, flow braking and unloading of the medium with decreasing pressure, as well as cooling of the material after complete removal of the mechanical load are studied.