A Rainbow Metamaterial For Broadband Multi-frequency Vibration Suppression

In this study, we propose a rainbow metamaterial to achieve multi-frequency broadband vibration suppression. A U-shaped beam is partitioned into subspace by parallel baffle plates. Cantilever-mass microstructures are then attached to the each subspace of the composite beam to tune its vibration. Instead of being uniform, these vibration absorbers are rainbow-shaped for the purpose of suppressing vibration within broad frequency band. An analytical model is first developed to estimate the frequency response function of the composite beam. The interaction forces between cantilevers and the beam are calculated by solving the displacement of the mass absorbers. The baffle plates are considered as attached mass with both vibration and rotation considered. Subsequently, the analytical model is validated by comparison with finite element models and experimental results. On the basis of the analytical model, numerical study is conducted to explore the influences of mass distributions on the frequency response property of the composite beam. Results show that composite beam with rainbow-shaped mass posses broad stopband than that with uniform mass. Multi-frequency range vibration suppression can be also achieved for beams with rainbow-shaped mass on both the left and right sides.