Buckling of imperfect laminated cylinders under hydrostatic pressure

The objective of this paper is to investigate numerically the influence of the windinginduced geometrical imperfection on to the elastic buckling load of submersible composite hulls. A linear Sanders-type buckling model of laminated cross-ply cylinders is developed. The imperfection is modeled by an axisymmetric thickness default of each composite ply by analogy to the real laminate ply imperfections. The effects of these defaults are taken into account by correcting the laminated stiffness coefficients. Numerical examples have been performed analyzing three types of stacking sequences for thin carbon/epoxy cylinders. For each case, the geometrical imperfections induce significant buckling load reductions. The results of the proposed approach appear to be in good agreement with standard FEM code calculus.