A nonlinear finite element program was developed for the stress and failure analysis of composite laminated shell structures. By using the finite element program developed, the stress and failure analyses of graphite/epoxy filament wound pressure vessel with circular holes were conducted. In the nonlinear formulation, the updated Lagrangian scheme was adopted with the second Piola-Kirchhoff stress tensor and the Green strain tensor. For the finite element modeling of the vessel with holes, the eight node degenerated shell element was utilized. The variations of fiber direction and dome-thickness along the meridian of vessel were considered by defining the fiber angle at the center of each element and the thickness at each nodal point. As numerical examples, the stress analyses for the graphite/epoxy filament wound pressure vessels with various hoop winding thicknesses and boss radii were conducted. The behavior of pressure vessel with holes were compared with those without holes. The effects of the hole size and the hole cap condition were investigated as well. The behavior of pressure vessels were largely dependent on the hole size and the hole cap condition. Failure analysis was conducted considering stiffness reduction and unloading. The burst pressure of filament wound pressure vessels were estimated by the pressure of occuring the first failure of fiber.
