The Effect of Imperfections on the Buckling of Thin Walled Cylindrical Shells

Citation

Ditchey, Robert Louis (1973) The Effect of Imperfections on the Buckling of Thin Walled Cylindrical Shells. Engineer's thesis, California Institute of Technology. doi:10.7907/TPE9-EM80. https://resolver.caltech.edu/CaltechTHESIS:09232010-145835690

Abstract

A theoretical study of the effect of imperfections on the buckling load of a circular cylindrical shell under axial compression was carried out. The nonlinear shell equations of Donnell are solved in an approximate manner using the Potential Energy Theorem. The method of derivation and the resulting algebraic equations are com-pared to previous derivations which use a different method of solution. It was found that the resulting equations are identical to the ones derived by Galerkin's procedure, lending credence to that method. A parametric study of an imperfection model was carried out numerically. The imperfection model is similar to that originally used by Donnell, having amplitude decay with increasing wave number. The results show the effect of various rates of decay of amplitude with wave number, as well as the effect of various assumed amplitudes. Using these parameters, it is shown when shell buckling is dominated by long wave imperfections as opposed to classical short wave imperfections. It was found that if the decay of asymmetric imperfections with axial wave number is sufficiently high, that long wave imperfections can dominate. In the range of values chosen for these parameters, changes in the axisymmetric imperfection model had little effect on buckling behavior as compared to the changes in sensitivity to long waves which occur as the asymmetric model is varied.

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