Aeroelastic shape optimization of solid foam core wings subject to large deformations

This work presents studies on static aeroelastic shape optimization of aircraft wings subject to large deformations. The physics are captured using a coupled 3D panel method and a nonlinear co-rotating beam finite element model. The wing is defined by a series of airfoils that are parameterized based on the definition of NACA 4-digit airfoils.

The method assumes a solid cross section of isotropic material which is representative of foam core wings. Analytic expressions are derived for most of the cross-sectional stiffness properties, while approximations are introduced for the location of the shear center and the torsional stiffness. Optimized designs achieved using linear and nonlinear deformation models are compared and features are discussed.

The objective is to minimize drag subject to constraints on geometry, tip displacement, and root bending moment. Results highlight the importance of using nonlinear models to accurately capture changes in wingspan due to large deformations, as even small differences in the wingspan can have a large effect on the induced drag.

Non-planar wings with raised and drooped wingtips are also optimized, where drooped wings are found to achieve larger lift-to-drag ratios due to the increase in effective wingspan in the deformed configuration.