23rd Congress of International Council of the Aeronautical Sciences, 8-13 September, 2002, Toronto, Canada
Paper ICAS 2002-4.1.3

NONLINEAR AEROELASTIC SIGNAL ANALYSIS OF AN AIRFOIL-AILERON COMBINATION

H. Alighanbari
Ryerson University, Canada

Keywords: aeroelasticity, flutter, nonlinear dynamics

An airfoil-aileron combination is modeled as a three-degree-of-freedom system oscillating in plunge, pitch and aileron angular deflection, and subject to incompressible flow. The aeroelastic behaviour of the system is investigated taking into account freeplay nonlinearities in the pitch and aileron restoring moments of the airfoil. Then, the time series of the nonlinear system response are analyzed using the nonlinear dynamics methodology of parameters identification. The estimated parameters obtained via the signal processing technique are then compared with those directly calculated from the model. In the signal processing technique, first the phasespace is reconstructed using the mutual information function and the percentage of false neighbours methods. The dynamics of the system is then determined from the Lyapunov exponents. This paper discusses the limit cycle oscillations and chaotic behaviour of the 3-DOF aeroelastic system, and the tools to analyze these phenomena.

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