Peculiarities of Strengthening of Spherical Composite Pressure Vessels with Thin Metal Shells Under Static and Dynamic Loads. Part 1. Statics

A mathematical formulation of the boundary value problem of elasticity theory for a hollow metal-composite two-layer sphere under the action of internal static or centrally symmetric dynamic pressure is given. The problem is solved analytically for static loading in the exact formulation. Specific features of solutions for shells with an ultra-thin inner metal layer are investigated analytically. It is found that as the thickness of the inner more rigid layer decreases, the circular stresses in it increase in proportion to the ratio of the spherical stiffnesses of the materials of the inner and outer layers. This may lead to the fact that pseudo reinforcement of the composite shell by a very thin inner sufficiently stiff and strong metal layer will not only be ineffective, but may even cause destruction of the inner layer and, consequently, of the shell as a whole under loads which are quite safe for a composite shell without an inner pseudo-reinforcing layer.