# NONLINEAR ANALYSIS OF VISCOELASTIC RECTANGULAR PLATES

## Palavras-chave:

Viscoelastic plates, Kelvin-Voigt model, Nonlinear vibrations## Resumo

In this work, the non linear vibrations of thin, viscoelastic and isotropic clamped

rectangular plates, subjected to concentrated harmonic load are studied. The Von Karman

non linear strains relations are used and to describe the clamped boundary conditions,

rotational springs are considered. The viscoelastic material is described as the Kelvin-Voigt

model and the Raylrigh Ritz method is used to obtain a system of non linear dynamic

equilibrium equations with 39 degrees of freedom which is solved, in turn, by the Runge-Kutta

tnethod. A parametric detailed analysis is performed to study the influence of axial load,

viscosity parameter and geometry on the non linear response of the plate. The frequency-

amplitude relation and resonance curves were plotted. The frequency-amplitude curves

showed that as the viscosity parameter is increased, the maximum amplitudes and the degree

of nonlinearity are reduced, it was also observed that when both the dimentions of the plate

and external load are increased, the frequency-amplitude relations are quasi linear, The

resonance curves showed that the plate has a typical hardening behavior with two coexisting

atractors with high sensitivity to initial conditions.