Multi-objective optimization of a composite wing subject to strength and aeroelastic constraints

Abstract

This article presents a multi-objective optimization of a large aircraft composite wing subject to multiple constraints including strength, damage tolerance, and aeroelastic stability. Based on a preliminary design of the wing structure, the investigation demonstrated a multi-disciplinary design optimization process to replace the usual manual iteration of finite element analysis in the detailed design phase. For potential application, the optimization process was performed by making the full use of the commercial software MSC Nastran, which is widely employed in aerospace industry. The optimization procedure was divided into two stages according to the design objectives. This allows the designer to interact and make decision in the design process. The first stage was focused on the minimum weight optimization subject to the multiple constraints. The laminate ply thickness and orientation of the wing skins were taken as design variables. The optimized structure weight was reduced by 44.6 per cent. The second stage was focused on aeroelastic tailoring to reduce the wing gust response to the same level as the original value of the preliminary design with a minimum weight penalty. This led to the final optimized structure weight saving by 34.5 per cent. A post-process was performed to trim the optimized skin laminate layup and ply thickness under the manufacturing constraint. For a conservative design, an option of increasing the skin laminate thickness was made and led to a slight increase of the structure weight. However, the final weight saving is still over 30 per cent. A practical optimum design of the composite wing structure with significant weight saving can be achieved by a practical approach.