Flutter based aeroelastic optimization of an aircraft wing with analytical approach

We present an analytical flutter prediction methodology employing assumed mode technique for three dimensional wing and wing/store configurations. The flutter solution makes use of Lagrange formulation for aeroelastic modeling and Theodorsen function for aerodynamic load calculation. An in-house flutter code is developed and validated by using benchmark problems, next applied to Goland and AGARD 445.6 wing models. Flutter results in all cases are in excellent agreement with the reference data. The flutter code is further enhanced to enable aeroelastic optimization and uncertainty based flutter analysis of AGARD 445.6 wing/store configurations. Firstly, aeroelastic optimization study varying input parameters such as taper ratio, sweep angle, spanwise elasticity and shear modulus is performed to maximize flutter boundary of AGARD 445.6 wing and an optimum clean wing model is ascertained. Next, the structural effects of designated external masses are investigated for flutter of initial and optimized AGARD 445.6 wing models and optimum configurations of store placement are determined. Finally, structural randomness such as in spanwise elasticity and shear modulus of the wing are propagated through flutter analyses and this uncertainty quantification is applied to initial and optimum AGARD 445.6 clean wing models. Finally, for wing/store models, random parameters relevant to store masses, store load placements are added to material property uncertainties and similarly flutter boundary uncertainty is examined. In all analyses, uncertainty quantification is accom- plished by Monte Carlo Simulation method with various Coefficient of Variation estimates.