IRREVERSIBLE DEFORMING AND HEATING OF AN ELASTOVISCOPLASTIC MATERIAL IN A ROUND PIPE WITH A LUBRICANT LAYER

The paper presents a non-isothermal boundary value problem of material deformation in a rigid round pipe in the presence of a lubricant layer within the large strain model. Deformation and movement of the material and lubricant occur under a pressure difference increasing with time. Initially, the adhesion conditions are satisfied at the boundary of the pipe with the lubricant, then, as the load increases, the lubricant begins to slip, and friction against the pipe causes its heating. Heating of the materials also takes place in the process of accumulation of plastic strains. The base material and the lubricant have elastic, viscous and plastic properties, and also have different values of elastic moduli, yield strength and viscosity coefficient. The dependence of yield strengths and viscosity coefficients on temperature is also taken into account. Reversible deformation, occurrence and development of viscoplastic flow in the lubricant layer and flow propagation into the base material are considered.