Nonlinear Vibrations of Wind Towers with Variable Cross Section and Elastic Foundation Under Base Excitation

Resumo

In this work, the nonlinear vibrations of coupled tower-nacelle-blade system, considering variable cross section and elastic foundation, subjected to base excitation (harmonic and seisme) are studied. For this, the nonlinear Euler-Bernoulli beam theory is applied to model the tower and nacelle and the elastic base is described as a Winkler model, considering contact problem. The Rayleigh-Ritz method together with Hamilton principle are applied to obtain the set of nonlinear dynamic equilibrium equations which are, in turn, solved with the fourth order Runge-Kutta method. Numerical results show the strong influence of parameters and base excitation on the natural frequencies, on the resonance curves and on bifurcation diagrams.