Controle de um sistema dinâmico rotativo utilizando mancais com atuadores LMF

Abstract

Most rotating machines, especially those mounted on flexible shafts and bearings when it’s accelerating, tend to pass through critical speeds, which are speeds that can cause structural resonance in the system. Thus, there is a constant concern for seeking effective methods to reduce the effect of vibration when passing through such speeds. Currently there are many applications of "smart materials" as actuators in dynamical systems, in order to reduce vibrations in a frequency range next to the resonance zone. In this direction the use of actuators composed by shape memory alloys (SMA) assists in active control structures, due the capacity of stiffness variation with change of the temperature. This thesis presents a shaft-rotor system design with active bearing, using SMA springs and temperature control system based on fuzzy logic, to reduce the vibration amplitudes when passing through critical speeds. This reduction occurred from the system stiffness change (active support bearing), obtained by changing the temperature of the SMA springs. The theoretical and experimental results showed the system functionality, being achieved reductions of up to 61.5% in the peak amplitudes and 57.3% in terms of RMS signal during the passage through resonance zone.