Creep and long-time fracture of a cylindrical shell under external pressure in the presence of an aggressive medium

We consider the process of deformation and fracture of an oval ring modeling the behavior of a long cylindrical shell subjected to distributed external pressure. The shell deformation is studied in both the presence and absence of an aggressive medium. The hypothesis of nonlinear viscosity with a singular component is taken for the constitutive relation used to estimate the metal characteristics. This relation allows for the difference between the tensile and compression strength of the material. The singularity permits taking into account not only the nonlinear viscosity but also instantaneous fracture characteristics. We show that an aggressive medium can substantially decrease the shell operation life.