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Investigation of stability of aeroleastic systems excited by multiplicative noise

Irmela Zentner
Abstract : This research deals with the prediction of flutter instabilities which play a major role in the design and certification of civil aircraft. This kind of instability is due the aeroelastic coupling and is generated by efforts which are induced by the displacement of the structure within the fluid. We consider here the impact of atmospheric turbulence which also provides a contribution to the aerodynamic forces. In this thesis, turbulence is modeled by a stationary stochastic process introducing a multiplicative excitation into the aeroelastic coupled system. It is then necessary to develop methodologies capable to indicate stability of aircraft when multiplicative random noise is present. We will, indeed, study stability in the framework of random dynamical systems and more precisely by means of the Lyapunov exponents which give the exponential growth rate of the system. They thus generalize the notion of the real part of an eigçnvalue. Despite the development of reduced order models, the coupled systems are still rather complex and of high dimension. This is why we determine the largest Lyapunov exponent by numerical simulation. However, stability is also very sensible to the presence of structural nonlinearities as for example freeplay. We propose a method using on the one hand a dynamic substructuring method allowing to isolate the non regular parts which are due to freeplay and on the other hand a formulation by means of differential inclusions.
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Submitted on : Thursday, December 22, 2005 - 8:00:00 AM
Last modification on : Thursday, December 22, 2005 - 8:00:00 AM
Long-term archiving on: : Thursday, September 30, 2010 - 7:13:58 PM

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Irmela Zentner. Investigation of stability of aeroleastic systems excited by multiplicative noise. Engineering Sciences [physics]. Ecole des Ponts ParisTech, 2005. English. ⟨pastel-00001519⟩

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