Asymmetric Dynamic Buckling of Isotropic/ Anisotropic Spherical Caps

This paper deals with nonlinear asymmetric dynamic buckling of clamped isotropic/anisotropic spherical shells under suddenly applied pressure loads. The formulation is based on first-order shear deformation theory and Lagrange's equation of motion. The nonlinearity due to finite deformation of the shell considering von Karman's assumptions is included in the formulation. The buckling loads are obtained through dynamic response history using Newmark's numerical integration scheme coupled with a Newton-Raphson iteration technique. An axisymmetric curved shell element is used to investigate the dynamic characteristics of the spherical caps. The pressure value beyond which the maximum average displacement response shows significant growth rate in the time history of the shell structure is considered as critical dynamic load. Detailed numerical results are presented to highlight the influences of shell geometric parameter, orthotropicity, ply-angle, number of layers and asymmetric mode on the critical load of spherical caps.