stability, shell, stress, strain, plasticity, elasticity. 

Stability of double layer spherical shell is under consideration. An internal layer of shell is elastic, an external one is elastoplastic. First, the subcritical stress-strain state has been determined. Second, stability of ground state of composite spherical shell has been examined. This involves balance equations for internal and for external layer of shell, that written in perturbations, using identified boundary conditions. Next, problem of critical pressure determination can be reduced to the eigenvalue problem with respect to the time factor. As a result, relations between critical external pressure and internal and external radius of the shell have been received.

1. Sporykhin Anatoliy Nicolaevich, Dr. Sci. Phys. & Math., Professor, mechanics and computational modeling Department, Voronezh State University, Voronezh

2. Dmitrik Kirill Grigorievich, Postgraduate student, mechanics and computational modeling Department, Voronezh State University, Voronezh