Resposta e controle das vibrações de uma torre eólica usando MR-TLCD (magneto reológico-amortecedor de coluna liquida sintonizada)

Abstract

The wind towers are slender structures designed to handle the dynamic effects of wind action. A once excited, the tower can resonate causing rupture and failures in structure, blades and rotors. Besides preventing possible catastrophic failure the damping system could prevent premature fatigue in structural components of the tower between them the rotor and blades. The presence of damping vibration is limited when the system suffer forced vibration approaches of the resonance. In this context was developed a numerical model of a wind tower which determines the response of the structure under a forced excitation. The excitation was done by a dc motor unbalanced situated on the top of the tower. The structure consists of a metallic column with an electric unbalanced dc motor attached to a MR-TLCD damper. This dissertation was presented a Semi-active damper in which consists in U-tube format using magneto rheological fluid (Tuned Liquid Column Dampers with magneto rheological, MR-TLCD). The fluid existing inside the U-tube prevents the movement of large amplitude subject to the actions of external loads. In MR-TLCD is possible to reduce the kinetic energy of the fluid through the control valve. The fluid used in this work, when exposed in a magnetic field significantly increases its apparent viscosity. The motion equation of coupled system between the tower, electric motor and MRTLCD was formulated using the Lagrange equations. This dissertation was presented the regular and chaotic dynamic of a tower using a MR-TLCD damper through the numerical method of nonlinear dynamics, utilizing a time series, phase portrait, Fourier spectrum (FFT) and resonance curves. The characteristic of experimental model was used for developed the numerical model. Also the free vibration tests were utilized for determine the structural parameters of the system.