Synergistic Attenuation Mechanisms of Fluid–Solid Coupling and Local Resonance in Multi-Layered Cylindrical Lattices

Achieving low-frequency vibration attenuation in lightweight cylindrical lattices is critical for aerospace applications. This study proposes a multi-layered cylindrical lattice integrating five independent fluid cavities with locally resonant unit cells. To decouple the underlying attenuation mechanisms, a progressive design involving a continuous fluid column, segmented fluid cavities, and combined fluid–resonator configurations was investigated through experiments and finite-element simulations. Under the fully filled condition, the experimentally observed attenuation onset is approximately 684 Hz, compared with a numerically predicted onset of 631 Hz, while a strong attenuation regime extends to approximately 2000 Hz. Programmable fluid filling enables effective regulation of the attenuation onset, with the fully filled configuration exhibiting the lowest experimentally observed onset frequency. These findings demonstrate that fluid–structure coupling and local resonance can be synergistically exploited to achieve lightweight, broadband, and potentially tunable vibration isolation.