Gyroscopic Periodic Structures for Vibration Attenuation in Rotors

Rotordynamics and periodic mechanical structures - or mechanical metastructres - are two widely explored fields of knowledge in dynamical systems, each being its own universe with very specific practices and interests. The latter has been of particularly growing interest to the scientific community over the past years, and its expansion has found several intersections with the most diverse fields of study, such as acoustics, optics and seismology. However, the combination of mechanical metastructures and rotating axially symmetric systems - rotordynamics - is still a largely unexplored subject. In this work we propose the study of a simple rotor system with periodically attached resonators. Its dynamical behavior is investigated using the system’s transfer matrix. The gyroscopic effects acting both on the rotor and the resonators create interesting phenomena such as polarization of the whirl modes and ‘invisibility’ effects. A rainbow-type arrangement of resonators is also explored for translational and flexural resonators, showing good enhancement of attenuation performance. The interaction between resonators modes and rotor modes is explored and the impacts on vibration transmissibility is evaluated. The translational resonators showed significantly superior attenuation performance, both in amplitude and bandwidth. However, unique effects such as polarized invisibility and speed dependent bandgap formation where only achievable for the flexural resonators.