ANALYSIS OF AEROELASTIC STABILITY OF VISCOELASTIC SANDWICH PANELS IN SUBSONIC REGIME USING THE NONPLANAR DOUBLET-LATTICE METHOD

Resumo

The engineers of aeronautical industries are frequently facing with subsonic panel flutter phenomena,
where the design and analyses of aerospace vehicles requires the knowledge of their critical flutter speeds for
safety requirements and to avoid catastrophes. Thus, whenever possible it is important to evaluate efficient and
low-cost aeroelastic control strategies to deal with the problem of panel flutter phenomenon. In this context, the
use of passive constraining viscoelastic layers seems to be an interesting alternative to be used in such situations.
However, the structural and aerodynamic modeling procedures of an aeroviscoelastic system subjected to a
subsonic airflow are not easy. In most of the cases, the difficult is related to the fact that, the viscoelastic behavior
depends strongly on the excitation frequency and temperature, resulting in some difficulties during the coupling
between the structural and aerodynamic models to account for the unsteady aerodynamics and complex behavior
of the viscoelastic part, simultaneously. In this study, it is proposed an efficient numerical strategy to model
aeroviscoelastic systems under subsonic airflows for panel flutter suppression. Here, the curved plate model of a
thin three-layer sandwich panel and aerodynamic loadings using the nonplanar doublet lattice method are
constructed both in MATLAB® environment code. Also, to solve the resulting equations of motion of the complex
aeroviscoelastic system, an improved version of the p-k method is proposed herein to estimate the critical flutter
speeds and to verify the possibility of increasing the critical flutter speeds of the base panel by using viscoelastic
materials. The influence of design parameters characterizing the performance of the viscoelastic treatment and its
operation temperature on the flutter boundary has been also addressed herein.