Robust aeroelastic design optimization of wing/store configurations based on flutter criteria

We present a robust aeroelastic design optimization study for three dimensional wing/store configurations by employing an analytical flutter analysis. The flutter solution uses Lagrange equations with energy terms where structural displacements are represented by assumed mode technique and aerodynamic loads are calculated by Theodorsen function. An in-house flutter code is developed parametrically in terms of design variables such as taper ratio, sweep angle, elastic axis location and material properties, and validated by using available reference data for well-known aeroelastic benchmark problems which are the Goland and AGARD 445.6 wing models. The flutter code is coupled with an optimization software to perform deterministic design optimization of the AGARD 445.6 clean wing and then further developed to enable flutter analysis and optimization of wing/store configurations. The aeroelastic modeling counts for both structural and aerodynamic ef- fects of external masses while couple of different optimization strategies are applied to determine optimum store locations and wing design to maximize flutter speed. Finally, robustness criterion is implemented into aeroelastic optimization in the presence of structural uncertainties. These uncertainties are propagated by Monte Carlo Simulation (MCS) while 2^nd order Polynomial Chaos Expansion (PCE) is used through MCS to reduce the computational time.