A fish-skeleton-like metastructure isolator for low-frequency vibration isolation

Vibration isolation for vibration-isolated objects in low-frequency vibration environment has been widely concerned by researchers. In this paper, we designed a local resonant (LR) fish-skeleton-like metastructure isolator with cantilever beam oscillators for low-frequency vibration isolation. Based on the theories of wave dynamics and structural dynamics, we analytically obtained the bandgap characteristics and transmissibility of the metastructure by using the equivalent mass and stiffness method, and carried out simulations through the finite element method (FEM). This metastructure isolator was fabricated by a 3D printing equipment and the vibration isolation test was carried out. Vibration transmissibility characteristics is obtained through the analytical method, FEM and experiment show that the local resonance near the natural frequency of the oscillators can effectively suppress the vibration transmission. The specific performance shows that the vibration transmissibility is as low as 21 % at the center frequency of the bandgap, while the mass of the isolator is only increased by about 2.3 % compared with the ordinary structure which has no oscillators. With the increasing of the mass of vibration-isolated objects (650 g), the transmissibility can be as low as 4 %. In addition, the contribution of different frame bodies and different oscillators of the isolator on the isolation effect and a way of widening the isolation frequency ranges are clarified. The proposed fish-skeleton-like metastructure in the present work provides a new design approach for vibration isolation in engineering applications.