THEORETICAL MODEL AND LOW-FREQUENCY VIBRATION ISOLATION CHARACTERISTICS OF STACKED MIURA-ORI VIBRATION ISOLATORS

Low-frequency vibration is difficult to control due to the slow decay rate, which seriously influences the precision, stability and reliability of high-end equipment. The linear vibration isolator cannot effectively isolate the low-frequency vibration due to the inherent contradiction between the bearing capacity and the vibration isolation frequency band. Therefore, the quasi-zero-stiffness vibration isolator can be constructed by introducing nonlinearity to obtain equivalent negative stiffness and nonlinear stiffness to realize the low-frequency vibration isolation characteristics. Origami structures have unique mechanical properties such as bistability, negative Poisson's ratio, negative stiffness, etc., which have been concerned in recent years. Inspired by stacked Miura-ori (SMO) origami, a novel SMO vibration isolator is proposed, which consists of an SMO structure and a linear spring connected in parallel. The potential energy equation of the SMO structure is derived based on the energy method, and the force-displacement relationship is derived, which reveals the mechanism of the negative stiffness of the SMO structure with large stroke. The effects of different initial angles and crease stiffness ratios on the restoring force of the SMO vibration isolator under stress-free conditions are investigated, and the nonlinear stiffness adjustment mechanism of the SMO vibration isolator is revealed. The theoretical model of the SMO vibration isolator is established, and the displacement transfer rate is derived based on the harmonic balance method. The low-frequency vibration isolation performance under different loads was investigated by numerical simulation. Finally, a prototype of the SMO vibration isolator was developed, and the restoring force and low-frequency vibration isolation performance of SMO vibration isolator were verified experimentally. The results demonstrate that the peak frequency and transmissibility of the SMO vibration isolator are 1.52 Hz and 1.29. This study provides a new approach for the design of low frequency origami-inspired vibration isolators.