When designing aerodynamic structures, it is important to understand if, and under what aerodynamic conditions, the structure will be stable and unstable. This is especially true if a structure is inherently flexible, such as a wing, where unstable response leads to oscillations of the structure until failure occurs. Since structure design generally includes performance predictions, it is necessary to predict the aeroelastic response of a particular design. To do this, computational aeroelastic methods are used to simulate numerically an aeroelastic process using computational techniques that include the use of Computational Fluid Dynamics (CFD) codes. The value of the information generated by traditional CFD-based computational aeroelastic analyses is limited in that it can require a significant level of computational resources to generate and cannot be readily utilized by other disciplines involved in the overall vehicle design process.
A method was developed for performing CFD-based aeroelastic analyses that uses a mathematical model for structural modes of a flexible structure, and a nonlinear aerodynamic model that can generate unsteady aerodynamic responses based on the structural modes for conditions defining an aerodynamic condition of the flexible structure. A linearized state-space model is generated using a single execution of the nonlinear aerodynamic model for all of the structural modes. This single execution of the nonlinear aerodynamic model is carried out using a family of orthogonal functions as inputs. Then, static and dynamic aeroelastic solutions are generated using the linearized state-space model.