22nd Congress of International Council of the Aeronautical Sciences, Harrogate, UK, 28 August - 1st September, 2000
Paper ICAS 2000-4.6.4

PREDICTION OF NON-LINEAR AEROELASTIC INSTABILITIES

A. Sedaghat, J. E. Cooper, J. R. Wright, A. Y. T. Leung
Manchester University, UK

Keywords: non-linear elastic instability

This paper describes part of an investigation into the use of Normal Form Theory to predict and characterise Limit Cycle Oscillations (LCO) in non-linear aeroelastic systems. Starting with the coupled aeroelastic integrodifferential equations of a system with nonlinearities, it is shown how to reduce the order of the system and then compute the normal forms using a class of the period-averaging method. The stability of the LCO can then be characterised by considering the behaviour around the linear flutter condition. Such an approach does away with the need for numerical simulation of the system. The methodology is demonstrated upon a simple two-degrees-of-freedom aeroelastic wing model with cubic stiffness. A good agreement is obtained between analytical and simulation results.

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