Shell Structures
This project is concerned with the buckling failure of metal structures generally formed of curved plates. These structures are typically used in the liquid and bulk material storage industries, pressure vessels, aerospace vehicles, and in many other contexts. The analysis and design of pressure vessel closures may surprisingly sustain buckling failure under internal pressure. This is followed by a consideration of buckling under external pressure, firstly in the context of the Donnell stability equations which provide solutions of good accuracy in many cases, but secondly using the more rigorous and generally more accurate Flügge equations in coupled form. The latter theory is applied to cases of uniform and non-uniform pressure such as wind and patch loading. A further advantage of the theory is that solutions are possible for non-classical boundary conditions. Solutions are tabulated for uniform, hydrostatic, wind and patch loadings. Buckling under in-plane compressive forces is also briefly considered. Experimental and prototype responses under several loading regimes are examined and the significance to design considered; included are buckling problems associated with corrugated plates. When tank structures are supported on soils of non-uniform stiffness, differential settlement may occur, causing possible overstress or even buckling failure. Analyses based on inextensional theory are valid at low harmonic number in open-top tanks, while finite element analysis is the most general and accurate tool for the linear and non-linear stress and buckling response.
The non-linear behaviour and coupled instabilities of steel cylindrical tank shells subjected to meridional edge deformation of harmonic pattern are investigated. The harmonic number n is shown to have a strong influence on the shear and meridional buckling interaction. Practical applications are related to the design and maintenance of storage tanks and silos. The shear buckling mode is observed at small harmonic number n (<5) in shells of uniform thickness; with increasing n, the mode is dominated by axial buckling. As the shell deforms in the shear buckling mode, it continues to carry higher load until local buckling occurs near the base. In tapered shells, shear buckling occurs in the upper region of the shell at high n.