Design Optimization Using Lamination Parameters for Next Generation High Aspect Ratio Wing

A modern aircraft structure, such as a next generation high aspect ratio wing, consists of a number of composite panels in the design of which weight, structural performance, and manufacturability become the primary drivers. In this work, a bilevel weight optimization approach is followed. This study investigates the use of non-conventional structural configurations of next generation highly flexible composite wings aiming at weight reduction subject to a number of constraints including structural strength, avoidance of buckling, and required stiffness distribution. A bilevel lamination parameter-based approach is followed for weight optimization of the composite wing structure. At the top-level lamination parameters and numbers of plies of the predefined angles (0, 90, 45 and -45\textdegree) are used as design variables, the weight is treated as an objective function to be minimized subject to the buckling, strength, and ply percentage constraints. To enhance the optimization process, a genetic algorithm in conjunction with the surrogate modelling is employed at the top level, resulting in improved efficiency and enhanced global search capability. At the bottom level, the composite stacking sequence is obtained subject to the requirements of blending and preservation of mechanical properties. To obtain a valid composite stack and enable inter-panel composite ply blending, a permutation form of a genetic algorithm is used for matching the lamination parameter values passed from the top level optimization while satisfying the layup rules.