Aerostructural Adjoint Method for Flexible Wing Optimization

This paper presents the current developments at ONERA on wing optimization via the aero-structural adjoint method. The aero-structural adjoint is the extension of the aero-elastic adjoint already used in aerodynamic function optimization.1 The aero-structural adjoint method allows the improvement of both aerodynamic and structural functions in the same design space. The internal structural element thicknesses (spar webs, caps, skins), the structural characteristics (flexibility) and the planform parameters are all variable in the aero-structural adjoint-based design process. A module for structural modelling, wing weight estimation and adjoint-compatible structural sensitivities computation is presented. The material stresses are aggregated into the Kreisselmeier-Steinhauser function to reduce the high number of design structural constraints. The structural module is integrated with the existing aero-elastic environment for adjoint-based optimizations in order to perform drag and weight optimizations.