Buckling and Postbuckling of Spherical Shells with Apical Cutout Under Ring Load

摘要

The buckling and postbuckling behavior of elastoplastic spherical shells with circular apical cutout under a ring load was investigated analytically and experimentally. A finite element code based on the updated Lagrangian formulation was established to analyze this buckling problem by considering nonlinear geometric and material properties. An iterative scheme controlled by displacement was adopted in the solution procedure to avoid numerical instability near the limit buckling load. Ring loads of both line and strip types were analyzed. A testing device was used to perform buckling experiments. The ratio of diameter to thickness of the steel specimens was between 30.23 and 86.75. The influence of the ratio of diameter to thickness and the sizes of the apical cutout and ring load on the limit buckling load are discussed. The analytical results agree satisfactorily with experimental ones for medium-carbon steel spherical shells. Convex and concave modes of postbuckling deformation around the apex are obtained in analysis and observed in experiment for varied combinations of the sizes of ring load and apical cutout and ratio of diameter to thickness of the spherical shells.