Characteristics of a Quasi-Zero-Stiffness Isolator Using a Double-Curved Beam as a Negative Stiffness Mechanism

In this paper, a new quasi-zero-stiffness (QZS) nonlinear isolation system using a double-curved beam (DCB) as a negative stiffness structure is proposed, and its performance is investigated. The negative stiffness provided by the DCB to the isolator in the equilibrium position reduces the isolator's overall dynamic stiffness. Static and dynamic characteristics of the system are investigated. The amplitude-frequency characteristics and force transmissibility equation of the system were derived via the harmonic balance method. The effects of damping ratio and excitation force amplitude on amplitude-frequency and force transmissibility curves are examined, and the isolation performance is compared with that of an equivalent linear isolator supporting the same mass with the same static deflection as nonlinear isolators. Furthermore, MATLAB numerical simulation software is used to perform dynamic time analysis of the nonlinear isolation system. The results indicate that the amplitude-frequency curves of the nonlinear isolation system exhibit bending, accompanied by discontinuous jumps in frequency. The appropriate increase in the damping ratio or reduction in the excitation amplitude benefits the vibration isolation performance of the nonlinear vibration isolation system. Compared with the equivalent linear isolation system, the QZS isolation system exhibits a better low-frequency vibration isolation performance, which provides a theoretical basis for the design of low-frequency nonlinear isolators.