A metamaterial isolator with tunable low frequency stop-band based on magnetorheological elastomer and magnet spring

This paper proposed and prototyped a metamaterial isolator with periodic structure based on magnetorheological elastomer (MRE) and magnet spring. With acoustic metamaterial structure, the proposed metamaterial isolator can generate a stop-band, which means the vibration over specific frequency can't be transferred and will be isolated effectively. Then, with the control of MRE stiffness, the cut-off frequency of the stop-band is tunable, which makes the isolator potential to be adapted to different working situations. The negative stiffness generated by the magnet spring can help to lower the start frequency of the stop-band and enhance the bearing capacity of the metamaterial isolator in vertical direction in the meantime. To verify the feasibility of the proposed device, the magnetic field simulation was first conducted and discussed, and the negative stiffness property of the magnet spring was numerically measured and demonstrated. Then, the mass-spring model of the metamaterial isolator was established in order to theoretically analyze the influence of MRE and the magnet spring on the vibration attenuation efficiency. A vibration platform was finally set up and the evaluation experiments were conducted to validate the theoretical analysis. In this paper, the structure design, theoretical modelling and experimental results of the metamaterial isolator are comprehensively discussed, which demonstrate that the prototype structure can work well as expected. The design of the metamaterial isolator with negative stiffness magnet spring can also enlighten more studies on lowering the bandgap frequency of the acoustic metamaterial without sacrificing large structure stiffness.