Neutralizador dinâmico de vibrações torcionais viscoelásticos aplicado em sistemas rotodinâmicos

Abstract

Dynamic viscoelastic vibration neutralizers are devices used in the passive control of vibrations. The main characteristics that make them an advantageous choice are directly related to the viscoelastic materials used in the construction of these auxiliary systems. This doctoral thesis deals with the modeling of dynamic neutralizers applied to the problem of torsional vibrations in rotors, the final result of which is to define the viscoelastic and geometric parameters of the neutralizer, that is, in this approach, the material is defined later, from the Response of the physical system, obtained through modal analysis methods or finite elements. In this way, one can select or, eventually, synthesize the elastomer that best suits the on-screen problem. Therefore, this is the characteristic that differentiates the model proposed in this research from other already known models, in which the parameters of the auxiliary system are determined from a pre-selected material. The dynamic behavior of the linear viscoelastic material was described through the fractional model of four parameters and to validate the results of this modeling, a rotodynamic workbench was used, which allowed to evaluate the neutralizer in motion under the effect of torsional vibration. The introduction of torsional forcing was done by means of a remotely controlled angular excitation system. The solution to apply this excitation type overcomes, therefore, some of the difficulties of the torsional analysis with the spinning system. The results prove the effectiveness of the proposed fractional model and show the potential of the viscoelastic neutralizer for the control of torsional vibrations in rotors.