Utilização de material com características periódicas para redução de vibrações em rotor embarcado

Abstract

This work presents an elastic wave attenuation numerical method for onboard rotors with periodic material bases, materials with the ability to attenuate mechanical waves within certain frequency bands (bandgaps). Periodic bases are used to reduce the effects of external forces within onboard rotors, such as in aeronautical turbines, and the quality of machine tools finishing. In this study, two kinds of phononic materials were studied, the first one uses the Bragg Scattering mechanism and is composed of layers (lattices) of lead and epoxy, and the other one uses the local resonance mechanism being composed of lead lattices and a parallel mass-spring assembly. The dispersion diagram of the Bragg scattering phononic material shows a bandgap between the frequencies of 448 and 2587 Hz, and the locally resonant material presents a bandgap in the neighborhood of 60 Hz. Within its bandgap the periodic materials presented a significant reduction of the displacement produced by the base, however, the periodic base cannot affect the vibration generated by the internal components of the rotor (imbalance mass, components weight and elastic deflection), the displacement produced by the components of the rotor is of 10-4 meters. The simulations evaluated the vibrating behavior of an embedded rotor submitted to base excitations in continuous and periodic bases using the Bragg scattering and locally resonant materials, and the simulation results showed a significant reduction in the displacement amplitude of the periodic onboard rotor disc within its bandgaps frequencies.