Gear-tuning meta-shaft for low-frequency torsional vibration suppression

Metastructures can be engineered with low-frequency torsional band gaps, which provides a new solution for vibration suppression in shaft systems. However, achieving precise, reversible and robust tunability remains challenging, particularly in shaft systems due to the limited space preventing the implementation of tunable designs with complex mechanisms or additional control units. In this study, a tunable meta-shaft with self-locking gear (SLG) resonators is proposed, where the vibration suppression frequency range of the meta-shaft can be adjusted precisely with a simple gear-tuning mechanism without adding resonator's mass. By shifting the SLG teeth to control the deformation of the six curved beams in the SLG resonators, the torsional stiffness and resonant frequency can be effectively modulated, thereby enabling the generation of tunable low-frequency torsional band gaps. The torsional wave attenuation performance of the meta-shaft with periodically attached SLG resonators is evaluated numerically, and a prototype is fabricated to experimentally verify its robust and tunable vibration suppression capability. Consistent results among theoretical analysis, numerical simulations, and experiments verify the effectiveness and scalability of the proposed tuning strategy for adaptable torsional vibration control in shaft systems.