Chapter 9 - Imperfect spherical shells

Abstract

Spherical shells exhibit a number of applications as structural components, especially as pressure vessels. Very large thin-walled complete spherical shells are used as main structural components in pressurized water reactors (PWR) or pressurized heavy water reactors (PHWR) in nuclear power plants. Liquefied natural gas is transported by sea by large carriers that can have five spherical shells in line. High-pressure gas containers are another important application of large spherical shells. The tolerances in geometry adopted for the fabrication of such spherical shells are stringent; however it can happen that deviations from the as-designed geometry with amplitudes of the order of the shell thickness can occur as a consequence of damage of the shell. The chapter also presents equations for spherical shells and reviews the tools of analysis employed to compute the subsequent results. These tools include a finite element formulation for shells of revolution as the basis of a direct analysis of geometric and intrinsic imperfections, and a simplified equivalent load technique for geometric imperfections.