Stability of Pressurized Hyperboloidal Shells

The data obtained are compared with predicted results using a linear finite element stability analysis and a corresponding nonlinear analysis wherein the effects of geometric nonlinearities are included. Experimental buckling loads were in good agreement with linear theory predictions, and the geometric nonlinearities were found to have little effect on the calculated critical loads of the hyperboloids tested. The experimental results were also compared to analytical data for cylindrical shells. The ratio of experimental results to analytical predictions were far lower for cylindrical shells than hyperboloidal shells. These results indicate that hyperboloidal shells have a lower sensitivity to geometric imperfections than cylindrical shells. The experimental data for internally pressurized hyperboloidal shells under axial load indicate that the axial buckling value asymptoptotically approaches a constant value when the additional load carried by the internal pressure is subtracted. Sanders thin shell (strain-displacement) equations were used to develop finite element models for both the linear and nonlinear analyses.