Structural Sizing, Aeroelastic Analysis, and Optimization in Aircraft Conceptual Design

This paper presents a design tool based on computational methods for the aerostructural analysis and optimization of aircraft layouts at the conceptual design stage. The whole methodology is based upon the integration of geometry construction and aerodynamic and structural analysis codes that combine depictive, computational, analytical, and semiempirical methods validated in an aircraft design environment. The main module for structural sizing and numerical aeroelastic analysis, named NeoCASS (next-generation conceptual aerostructural sizing suite), is presented here. The numerical kernel handling the aerostructural interaction enables the creation of efficient low-order high-fidelity models that are particularly suitable within a multidisciplinary design optimization framework to drive the optimization tool in the most appropriate direction. This makes it possible to address adverse aeroelastic issues, such as divergence, control surface reversal, flutter, and increased drag at cruise speed due to structural deformation. All of these issues generally lead to considerable changes in the structural design, which in turn might pose limitations on the flight envelope or weight penalties. The late discovery of these types of issues may result in significant cost increases and, in some cases, it may lead to the termination of the project. To overcome and remove these issues, the influence of structural deformation on flight and handling performances, of weight, and of design costs needs to be taken into account as early as possible in the design process.