Influence of localized imperfection on the instability of isotropic/cross-ply cylindrical shells/rings under external pressure

Compressive response of two extreme cases of cylindrical shell type structures weakened by the presence of localized imperfections is investigated. These two extreme cases are (i) thin metallic cylindrical shells, which are characterized by the absence of transverse shear deformation, and (ii) thick laminated advanced fiber reinforced composite rings (very long cylindrical shells), whose response is dominated by the interlaminar or transverse (primarily shear) deformation. A fully nonlinear finite element analysis, that employs a cylindrically curved 16-node layer-element, and is based on the assumption of layerwise linear displacements distribution through thickness (LLDT) or linear displacements distribution through thickness (LDT), is utilized in the analysis of afore-mentioned cross-ply ring or thin homogeneous isotropic cylindrical shell, respectively. Hitherto unavailable numerical results pertaining to the two cases are also presented.