Buckling analysis and configuration optimum design of grid-stiffened composite panels

To allow an efficient preliminary design, a grid pattern or configuration optimization strategy is proposed for grid-stiffened composite structures under the constraint of sustaining the buckling resistant capability. This is achieved by first introducing a configuration vector for representing stiffeners in a grid unit, which is applicable for the description of iso-grid, ortho-grid X-grid, and bi-grid. The parametric equivalent stiffener model of the structure is derived by the smearing method, and the global and local buckling loads are calculated for the different grid configurations. The artificial bee colony algorithm was used as an optimizer to address the discrete design variable space, including a grid-unit size, height, and thickness of stiffeners that could be specified by designers or manufacturing requirements. Two test examples validated the effectiveness of the approach. The results suggested that both optimal and suboptimal solutions can be considered effectively as design options in the preliminary stage of design for such types of structures.