DISCRETE LAYER ANALYSIS OF ORTHOTROPIC, STIFFENED COMPOSITE CYLINDERS

A two-dimensional, curvilinear, isoparametric, finite element is used to provide a discrete layer analysis of deformations and stresses in s tiffened, cross-ply composite cylinders subjected to thermal-mechanica l loading. The generalized plane problem is analyzed by considering a discrete layer representation of a generic transverse cross section of the stiffened cylinder to provide the complete three-dimensional stat e of stress. Individual layers of the cylinder and the stiffener are m odeled explicitly, providing an accurate and detailed representation o f deformations and stresses including interlaminar stresses. Cross-ply skins with cross-ply or unidirectional stiffeners are studied for fab rication-induced residual thermal effects, applied axial strain, torsi on, and internal pressure loading. The analysis shows that local curva tures and interlaminar stress concentrations are present near the skin /stiffener joint, Interlaminar stresses are also present along the fee edge of the stiffener.