3. Design Procedure for Optimum Fiber Composite Airframe Structures Within an Automated Multidisciplinary Design and Optimization Process

This paper presents a concept and setup of a design procedure for optimum fiber composite airframe structures within an automated multidisciplinary design and optimization process. The optimization procedure is based on the Three-Columns-Concept, using a state-of the-art Finite-Element-Method (FEM) software for structural analysis purposes embedded into a multidisciplinary optimization software. The optimization model is formulated for traditional civil aircraft designs, providing maximum design flexibility in order to tailor-made the characteristics of fiber composite materials, including aeroelastic tailoring. Therefore, the design domain includes both, geometry and laminae related design variables. In doing so, a strict separation of the design model from the analysis model is implemented. The evaluation model includes all important structural design objectives, like mass, deformations (e.g. wing bending and twisting), local and global buckling behavior (classical eigenvalue analysis), strength as well as damage tolerance. Aggregation methods are applied to reduce the tremendous number of constraints and to improve the robustness of the optimization process. Finally, optimization results of a forward swept wing configuration, optimized with respect to structural design objectives, are presented.