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DINAME 2017
XVII International Symposium on Dynamic Problems of Mechanics
INFLUENCE OF VISCOELASTIC DAMPING ON THE DYNAMIC RESPONSE OF NONLINEAR AEROELASTIC SYSTEMS
Submission Author:
Thiago de Paula Sales , SP
Co-Authors:
Thiago de Paula Sales, Daniel de Almeida Pereira, Flavio D. Marques, Domingos Rade
Presenter: Thiago de Paula Sales
doi://10.26678/ABCM.DINAME2017.DIN17-0213
Abstract
Nonlinear aeroelastic systems are prone to the appearance of limit cycle oscillations, bifurcation and chaos. Such problems are of increasing concern in aircraft design since there is the need to control nonlinear instabilities and improve safety margins, at the same time as aircraft are subjected to increasingly critical operational conditions. On the other hand, viscoelastic materials have already been successfully used for the attenuation of undesired vibrations in several types of mechanical systems. However, a considerably small number of research works have addressed the feasibility of exploring the viscoelastic effect to improve the behavior of nonlinear aeroelastic systems. In this context, the objective of this work is to assess the influence of viscoelastic materials on the aeroelastic features of three-degree-of-freedom typical section models (including pitch, plunge and surface control motions) which present structural nonlinearities of the hardening stiffness type. The equations of motion of the system under analysis are derived in such a way that one is able to account for the dependence of the viscoelastic material properties on frequency and temperature. For this purpose, a constitutive law based on fractional derivatives is adopted, allowing for the modeling of the viscoelastic behavior in the time domain. The aerodynamic forces are introduced based on the classical theory of linear unsteady aerodynamics with corrections for arbitrary motions derived from Theodorsen’s method. The aeroelastic behavior is investigated through time domain simulations, and subsequent frequency transforms, from which bifurcations are identified, and diagrams of vibration amplitudes versus airspeed are constructed to characterize the conditions under which the system is supercritical or subcritical. The influence of the viscoelastic effect on the aeroelastic behavior, for different values of temperature, is highlighted and discussed. Numerical simulation shows that viscoelastic damping can increase noticeably the flutter speed and reduce the amplitudes of limit cycle oscillations for the system under consideration. These results show that viscoelastic materials can be used in the aircraft components to increase safety margins of the flight envelope as related to the aeroelastic stability
Keywords
nonlinear aeroelasticity, typical section model, cubic hardening, viscoelasticity, Flutter, limit cycle oscillation
