The influence of original imperfections on the equilibrium states of physically nonlinear panels

The influence of original imperfections, curvature of the panels, and the level of growth of plastic deformations on the equilibrium states of longitudinally compressed cylindrical panels have been studied. The physical relationships were established on the basis of the theory of localized deformations. It has been found that original imperfections substantially lower the upper critical stresses in the zone of elastic and slowly growing plastic deformations, depending on the curvature parameter a/R. In a zone of growing plastic deformations, the solution according to nonlinear shell theory approximates the solution according to linear shell theory, and change of curvature of the panels does not cause a sharp increase of the upper critical stress as occurs in a zone of plastic deformations.