A numerical analysis of a composite internally pressurized cylindrical vessel with spherical domes is presented. The structure is considered a filament winding process vessel in which a continuous strand of fiber is wound over a rotating male mandrel. During the winding process a variable thickness is created in the dome region which considerably alters its mechanical performance. Additionally, the fiber path depends on the surface where the fibers are wound; as a result the winding angle varies in the dome with regards to its longitudinal direction. The vessel is modeled as a non-structural internal liner reinforced with an orthotropic composite: carbon fiber reinforced plastic. Stress was calculated by applying the first-order shear deformation theory, and the Tsai-Wu failure criterion was considered as the limit state function of the laminate. The structure's optimum design is performed taking into account the main process variables, the winding angle and layer thickness. A finite element analysis was performed considering the winding angles as well as the thickness change through the dome, in order to study the effects of the winding process variables on the mechanical behavior of the composite vessel. A convergence study was carried out in order to verify the finite element analysis. It considered several shell element types. In order to model the structure, quadrilateral stress/displacement shell elements with 8-nodes (6-degrees of freedom each), quadratic interpolation and reduced integration were used.
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