Experimental and numerical analyses of the buckling of steel, pressurized, spherical shells

Abstract

Thin steel shells in the form of spherical segments, loaded by external pressure, have a tendency to sudden buckling under a lower pressure than their plastic resistance. The buckling phenomenon of spherical shells was the subject of research done by many authors and the previous results of theoretical and experimental research were used in the European Design Recommendations published in 2008 by European Convention for Constructional Steelwork. This article presents experimental research done on a specially designed and manufactured stand. Specimens were manufactured with a metal spinning technique from steel sheets usually used for deep drawing and stamping of metal objects. The actual shape of every specimen was determined with the three-dimensional scanning technique. Material research was also done on the steel sheets. Pressure was exerted with an air compressor and displacement was measured with the optical measurement system ARAMIS. The deformation modes of the whole specimen were registered precisely at every step of pressure exertion till the final postbuckling stage. All the data measured were registered automatically by two computers. The result of every experiment is presented in the form of an equilibrium path as the relationship of the pressure p as a function of a chosen displacement parameter. This article also presents a comparison between the critical pressures obtained during the experiments and the results obtained from the numerical simulations done with COSMOS/M. The experimental and the numerical results were also compared with the buckling resistances proposed by Rotter and Schmidt and Błażejewski and Marcinowski.