Low-frequency resonators filled with granular material for modal response treatment

Resonators are commonly employed as passive dampers to suppress structural vibrations. This study proposes a novel resonator concept designed for low-frequency control of a host structure, incorporating a granular-filled cavity to enhance damping and enable tunability of the target modal response. The resonator can be manufactured using additive techniques, and its resonant behaviour is estimated empirically from its geometry and material properties. The effect of multiple resonators on the modal response of the main structure is shown numerically and experimentally offering wider attenuation frequency bandwidth where bending modes of the main structure are successfully controlled. Incorporating only 10% volume fraction of granular material in resonator that have a negligible effect on its overall mass yields an additional 45% damping improvement and expands the effective attenuation bands.