Structural Stability Theory and Practice

8Buckling of Shells

8.1 Introduction

Shells are three-dimensional structures but the stresses can be considered in two planes only if the thickness of the shells is small in comparison to other dimensions. The difference between a shell and a plate is that a shell structure has an initial curvature whereas a plate is considered flat before an external load is applied. Because of their curved shape, shell structures are very efficient in supporting the external force. Shell structures are used in many industries to store and handle different materials. The materials stored by shell structures include solids, as in agricultural industries, and liquids such as gasoline and other petroleum products. Shell structures are used as water storage tanks and cooling towers in nuclear power plants. In recent times the size of the storage facilities has increased along with the use of high strength materials. In many cases, failure of these structures occurs due to instability before the material reaches its strength capacity. Therefore, there is a great deal of interest in the process of shell buckling nowadays. In the case of cylindrical shells, the buckling load reduces considerably when slight imperfections are present, which makes the analysis more important. In this chapter, the applications considered involve examples that can be solved by analytical methods. Practical structures and loads are much more complicated, which can now be solved by numerical methods with the help of computers. ...