Optimization and Postbuckling Analysis of Curvilinear-Stiffened Panels Under Multiple-Load Cases

Recent studies have indicated that panels with curvilinear stiffeners offer a strong potential for structural tailoring. However, the design complexity requires use of numerical analysis and optimization techniques. This paper considers the problem of optimal design of a stiffened panel with cutouts and curvilinear stiffeners, under multiple-load cases. Multiple failure modes are considered: buckling, damage tolerance, stress, and crippling. An optimization framework is presented to minimize mass of the stiffened panel by a combined shape and sizing optimization subject to constraints on the individual failure modes. Different panel thicknesses are allowed for each region bounded by stiffeners or panel boundaries. The framework uses Python scripts to couple ABAQUS-based analysis with VisualDoc optimization package. A design example is presented to illustrate the capability, and the optimized design is compared with that obtained using industry-standard practices. A postbuckling analysis of the optimal design with four curvilinear stiffeners is carried out and discussed in detail.