Effects of Variations in Structural Properties of a Generic Wing on Flutter Prediction

Traditional method for accounting for uncertainties in air vehicles is to design the air vehicle with sufficient margins to achieve fifteen percent excess flutter velocity margin for the entire operating envelope. Probabilistic methods can be used to account for the uncertainties and better predict the flutter margins. In order to better understand the role of uncertainties associated with the structure of the wing, Monte Carlo studies were carried out to calculate the impact of uncertainties seen in various structural parameters on the flutter characteristics of a generic wing, represented by a beam-rod Finite Element Model (FEM). The parameters varied in this study were sectional: mass, mass moment of inertia, elastic modulus, torsional modulus, polar area moment of inertia and the mass locations. To understand their impact on the flutter margin, variations in these parameters were studied for a range of uncertainty levels (different σ values) and correlation lengths. Results show that variations in chordwise mass location and the torsional rigidity of the wing have a strong influence on the variations in the flutter characteristics. Results also show that correlation length plays a dominant role in the variations seen in flutter characteristics.