Imperfection Sensitivity of Layered Composite Cylinders

The imperfection sensitivity of ring-stiffened anisotropic composite cylindrical shells under hydrostatic pressure is investigated using an asymptotic procedure. To this end, a finite-element formulation based on three-dimensional elasticity is developed. The displacement functions take the form of “exact” trigonometric functions along the circumferential direction and p -version-type hierarchic polynomial sets in the other two orthogonal directions. The buckling problem is explored in depth as a preliminary. Convergence studies on the critical pressures and the imperfection-sensitivity parameter are presented. Currently available results on critical pressures based on higher-order shear-deformation theory are cited for comparison. Fluid pressure loading is emphasized in contrast to the centrally directed loading. Comparisons of the maximum pressures as given by full-blown nonlinear analysis is presented. The imperfection sensitivities of several anisotropic and orthotropic laminate configurations are compared. The stiffened shells are investigated for their response in the “local” and “overall” buckling models separately. It is believed that the present approach is a very effective alternative to full-blown nonlinear analysis and can prove to be a powerful tool in preliminary design.