Imperfection sensitivity of thin elastic cylindrical shells subject to partial axial compression

Abstract

The paper addresses the buckling of an elastic cylinder under non-uniform axial compression applied at one boundary. It presents a systematic numerical investigation of the nonlinear load carrying behavior and imperfection sensitivity of the shell when a non-uniform axial load is applied to one end in the form of two equal-length uniformly loaded zones, diametrically opposite each other. Four imperfection forms are examined: the linear bifurcation mode, the nonlinear buckling mode, several post-buckling deformed shapes for the perfect shell, and a weld depression. Additional aspects, such as the influence of the weld depression position and its wavelength are also investigated. Special attention is given to the mesh convergence study and the sign of the imperfection amplitude. The numerical results demonstrate that the mode of the lowest linear bifurcation load is not always the `worst' imperfection form. It is also shown that the critical position for a weld depression can be approximately located by examining the nonlinear buckling mode of the perfect shell and that the weld depression generally causes the lowest buckling load for this load case.