Abstract
This paper presents a novel quasi-zero stiffness (QZS) isolator designed by combining a disk spring with a vertical linear spring. The static characteristics of the disk spring and the QZS isolator are investigated. The optimal combination of the configurative parameters is derived to achieve a wide displacement range around the equilibrium position in which the stiffness has a low value and changes slightly. By considering the overloaded or underloaded conditions, the dynamic equations are established for both force and displacement excitations. The frequency response curves (FRCs) are obtained by using the harmonic balance method (HBM) and confirmed by the numerical simulation. The stability of the steady-state solution is analyzed by applying Floquet theory. The force, absolute displacement, and acceleration transmissibility are defined to evaluate the isolation performance. Effects of the offset displacement, excitation amplitude, and damping ratio on the QZS isolator and the equivalent system (ELS) are studied. The results demonstrate that the QZS isolator for overloaded or underloaded can exhibit different stiffness characteristics with changing excitation amplitude. If loaded with an appropriate mass, excited by not too large amplitude, and owned a larger damper, the QZS isolator can possess better isolation performance than its ELS in low frequency range.
Highlights
The requirements for low-frequency isolators arise in many scientific and industrial fields, ranging from the isolation of precision instruments for gravitational wave detections to the design of seat suspension systems for motors [1, 2]
To overcome the limitation between isolation performance and static deflection, passive nonlinear isolators have been used to obtain a high static stiffness resulting in a small static deflection and a low dynamic stiffness resulting in a small natural frequency [4]
We introduce the theoretical design and characteristics analysis of a novel quasi-zero stiffness (QZS) isolator
Summary
The requirements for low-frequency isolators arise in many scientific and industrial fields, ranging from the isolation of precision instruments for gravitational wave detections to the design of seat suspension systems for motors [1, 2]. For traditional passive linear isolators, a smaller stiffness is desired to achieve a smaller natural frequency so that it can attenuate low-frequency vibrations [3]. In this case, a larger static deflection is unavoidable in practical applications. To overcome the limitation between isolation performance and static deflection, passive nonlinear isolators have been used to obtain a high static stiffness resulting in a small static deflection and a low dynamic stiffness resulting in a small natural frequency [4]. By choosing the appropriate configurative and geometric parameters of nonlinear isolators, a quasi-zero stiffness (QZS) isolator possessing zero dynamic stiffness at the static equilibrium position can be realized [5]. Le and Ahn [13] studied a low-frequency isolator for vehicle seat theoretically and experimentally, in
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