A segmented-gradient honeycomb sandwich metastructure for broadband vibration attenuation

Lightweight engineering structures commonly face difficulty in suppressing low-frequency broadband vibrations. Locally resonant metastructures, constructed by periodically or distributively integrating resonant units into host structures, exploit the resonance effect to achieve low-frequency broadband vibration attenuation, offering a promising solution. This study proposes a class of segmented gradient honeycomb sandwich metastructures (SGMs), in which a piecewise geometric-ratio function is introduced to tailor the resonant frequencies. This approach substantially compresses the structural design space while achieving excellent low-frequency broadband vibration suppression. First, an equivalent finite element model of the SGM is established based on the representative volume element method and first-order shear deformation theory. The effects of the number of segments, frequency common ratio, and center frequency on the bandgap characteristics are then investigated. On this basis, a genetic-algorithm-based bandgap performance customization method is developed, aiming to broaden the bandgap at a prescribed center frequency. Experimental results demonstrate that the bandgap center frequency of the customized SGM agrees with the target value, the bandgap width is approximately 70% wider than that of its periodic counterpart, and the theoretical predictions are in good agreement with the experimental measurements.