Uncertainty Quantification in Flutter Analysis for an Airfoil with Preloaded Freeplay

b = semichord Ch = damping coefficient in plunge C = damping coefficients in pitching h = plunge deflection I = moment of inertia about elastic axis K = linear stiffness coefficients in pitching K = linear stiffness coefficients in plunge m = mass S = static moment about the elastic axis U = velocity U = nondimensional velocity = pitching angle = nondimensional time ! = natural frequencies in pitching modes ! = natural frequencies in plunge modes