Design of low-frequency circular metastructure isolators with high-load-bearing capacity

Traditional vibration isolation structures cannot work effectively for low-frequency vibration under heavy loads, due to the inherent contradiction between the high-static and low-dynamic stiffness of these structures. Although the challenge can be effectively addressed by introducing a negative stiffness mechanism, the existing structures inevitably have complex configurations. Metastructures, a class of man-made structures with both extraordinary mechanical properties and simple configurations, provide a new insight for low-frequency vibration isolation technology. In this paper, circular metastructure isolators consisting of some simple beams are designed for low-frequency vibration, including a single-layer isolator and a double-layer isolator, and their static and dynamic characteristics are studied, respectively. For the static characteristic, the force-displacement and stiffness-displacement curves are obtained by finite element simulation; for the dynamic characteristic, the vibration transmissibility curves are obtained analytically and numerically. The result shows that the circular nonlinear single-layer isolator has excellent low-frequency isolation performance, and the isolation frequency band will decrease about 20 Hz when the isolated mass is fixed at 1.535 kg, compared with a similar circular linear isolator. These static and dynamic properties are well verified through experiments. Our work provides an innovative approach for the low-frequency vibration isolation and has wide potential applications in aeronautics.