Multiple geometric defects : their effect on stability of cylindrical shells

Thin isotropic circular cylindrical shells of near perfect quality were tested in axial compression with multiple local geometric defects imposed on them. The defects were in the form of diamond-shaped 'Yoshimura-facet-type' dimples, with large amplitudes, of the same order of magnitude as that of the facets in a cylinder buckled in axial compression. This investigation was performed in continuation of a previous study on the effect of single local defects on the stability of axially loaded cylinders. Apart from establishing the changes in load-carrying capacity with increasing number of defects, the present set of experiments reveals certain behavioral aspects of the defects, providing insight into how they affect the overall shell stiffness and its stability. Based on the test results, an empirical formula relating the reduction in buckling load to the number and size of the local defects is developed. (Author)