Analytical Solution to the Creep Problem of a Viscoelastic Material in a Round Tube

With the use of a mathematical model of large deformations of materials with elastic, plastic, and viscous properties, an analytical solution was obtained for deformation under creep conditions of a plug in a round tube with a varying pressure drop. The motion is considered taking into account the sliding of the material in the vicinity of the rigid wall of the pipe and its deformation under increasing, constant, and decreasing pressure. The displacements, reversible and irreversible deformations, and stresses at all stages of deformation, including residual deformations and stresses at full unloading, are calculated.