Estudo da influência do amortecimento viscoelástico no fenômeno aeroelástico de Flutter

Abstract

This work proposes an investigation of the influence of viscoelastic damping on the dynamic aeroelastic behavior of aeronautical systems. The stability analysis is made by using typical section models with two and three degrees of freedom. In the first one plunge and pitch motions are considered and in the second the rotation of a control surface is also included. The viscoelastic damping is introduced in the system as dissipative devices which act as viscoelastic springs. Regarding the aerodynamic modeling, it is assumed unsteady theory, which considers the vorticity effects associated to air flow. The k method is used to calculate the flutter boundaries. The goal of this work is to evaluate the influence of viscoelastic behavior on critical flutter speed. The equations of motion are modified to take into account the dependence of the viscoelastic behavior with respect to frequency and temperature, using the concepts of complex modulus and shift factor. In the time domain analyses it is used the fractional derivative model to represent the viscoelastic behavior, associated to a rational function approximation of the aerodynamics. The numerical simulations lead to conclude that the viscoelastic damping can effectively increase the flutter speed range. Furthermore, the parametric evaluation conducted shows the strong dependence of the aeroviscoelastic behavior with respect to temperature and geometry of the viscoelastic suspension devices.