In view of high specific strength and specific modulus, stiffened composite panels have been widely used in modern engineering fields. However, stiffened composite panels can develop buckling failure under service conditions as they are generally very thin. The buckling strength of stiffened composite panels is usually sensitive to the variation of boundary conditions, stacking sequences and lamina thickness. In order to permit stiffened composite panels to be designed efficiently with high reliability and safety against buckling, a parametric study to investigate the effects of boundary conditions, stacking sequences and lamina thickness on buckling strength of stiffened composite panels with various types of stiffeners is presented in the paper.
The accurate buckling analysis of stiffened composite panels can be achieved by an incremental nonlinear finite element analysis. However, the complete incremental nonlinear solution of a stiffened composite panel up to buckling is in general expensive and thus a linearized buckling analysis for lowest buckling loads based on an updated Lagrangian formulation with the degenerated shell element and an explicit through-thickness integration scheme is presented in the paper. In this method, it is assumed that the pre-buckling deformations of the structure are small and buckling analysis of stiffened composite panels is considered as an eigenvalue problem. The numerical accuracy of the linearized buckling analysis has been proven to be effective by comparison with the experimental data of three graphite-epoxy stiffened panels with “blade” and “I” section stiffeners and two GRP hat section stiffened panels.
After analysis, the results of the parametric study shows that boundary conditions, stacking sequences and lamina thickness generally have significant and distinct influence on buckling strength of stiffened composite panels. However, the buckling strength of stiffened composite panels will increase significantly with the increase of the lamina thickness while the effects of stacking sequences on buckling strength vary with various boundary conditions and the influence of boundary conditions on buckling strength varies with various stacking sequences.