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This and the next two slides are from:
Uwe Hornung and Helmut Saal (University of Karlsruhe, Karlsruhe, Germany), “Buckling loads of tank shells with imperfections”, International Journal of Non-Linear Mechanics, Vol. 37, Nos. 4-5, June 2002, pp. 605-621, Special Issue: Stability & Vibration in Thin-Walled Structures, doi:10.1016/S0020-7462(01)00087-7
ABSTRACT: Buckling tests were performed with four tank structures under vacuum pressure with diameters ranging from 10 to 70 m. After discussion of geometric imperfections tolerated by the standards and methods of measuring geometric imperfections of that size the results of the measurements are reported. Some of these results are far beyond the tolerance criteria of standards for stability design of shells. However, the loads where a buckling failure of the tank occurs is underestimated with the application of these standards. Numerical investigations of the buckling behaviour of the shell with geometric imperfections of eigenmode-shape show that with the size recommended for this purpose by standards the analysis will miss the buckling phenomenon. Different shapes of imperfections are investigated in the numerical analysis with a sector model of the tank shell. Only the numerical investigation with a model of the complete tank shell with the measured imperfections gave results which agreed with the buckling phenomenon observed in the tests as well for the loads as for the location of the buckling loads.
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