Vibro-acoustic suppression in metamaterial sandwich plate using compressional-torsional coupling resonator

Reducing low-frequency vibration and sound radiation in lightweight sandwich structures remains a significant challenge due to the inherently long wavelength of low-frequency waves. In this study, we proposed a novel metamaterial sandwich plate with compressional-torsional coupling inertial amplification resonators to effectively attenuate low-frequency vibration and suppress sound radiation. The sandwich plate is integrally fabricated by 3D printing technology. A theoretical model for bandgap prediction is developed using Hamilton's principle. Theoretical, numerical, and experimental results converge to demonstrate that the proposed metamaterial sandwich plate exhibits superior low-frequency bandgap performance while ensuring the lightweight and compactness of the structure. The bandgap starting frequency of the compressional-torsional coupling resonator is 45 % lower than that of the conventional resonator, despite having identical mass and stiffness. Moreover, for the same bandgap starting frequency and stiffness, its mass is only 30 % of that of the conventional counterpart. Crucially, it also occupies significantly less space compared to the lever-type inertial amplification local resonator. This work introduces a promising strategy for the reduction of low-frequency vibration in engineering applications.