Influence of localized imperfection and surface-parallel shear modulus nonlinearity on the instability of a thin cross-ply cylindrical shell under external pressure

Compressive response of a thin cross-ply cylindrical shell of finite length and weakened by the presence of a localized imperfection is investigated. A von Karman type nonlinear finite element analysis that employs a cylindrically curved 16-node layer-element, and is based on the assumption of layer-wise linear displacements distribution through thickness (LLDT), is utilized in the analysis of afore-mentioned cross-ply thin cylindrical shell. Numerical results pertaining to the appearance of a limit or localization point on the equilibrium path due to the combined effect of local imperfection and surface-parallel (intra-laminar) shear modulus nonlinearity of the fiber reinforced lamina material are also presented.