An asymmetric quasi-zero stiffness vibration isolator with long stroke and large bearing capacity

Abstract

A novel passive asymmetric quasi-zero stiffness vibration isolator (AQZS-VI) comprising two linear springs acting in parallel with one negative stiffness element (NSE) is proposed, of which the NSE is mainly constructed by the combination of cantilever plate spring and L-shaped lever (CPS-LSL). The static model of the isolator is deduced considering the geometrical nonlinearity of the NSE and the bending deformation of plate spring. The nonlinear stiffness properties of the CPS-LSL and the AQZS-VI, as well as the nonlinear damping properties of the AQZS-VI are discussed. The absolute displacement transmissibility of the AQZS-VI under base displacement excitation is obtained using Harmonic Balance Method, and the effects of different excitation amplitudes and damping factors on the vibration isolation performance are analyzed. Better than other quasi-zero stiffness vibration isolators (QZS-VI) whose NSEs do not provide supporting force at zero stiffness point, the NSE of the AQZS-VI provides more supporting force than the parallel connected linear springs, which is very beneficial for improving the bearing capacity of the isolator. Compared with a typical symmetric QZS-VI with same damping property, the AQZS-VI has longer stroke with 2 low stiffness and lower peak value of displacement transmissibility. The prototype experiments indicate that the AQZS-VI outperforms the linear counterpart with much smaller starting frequency of vibration isolation and lower displacement transmissibility.The proposed AQZS-VI has great potential for applying in various engineering practices with superior vibration isolation performance.

Design and performance analysis of an adjustable quasi-zero-stiffness isolator with four parallel springs for different loads

“…Equation (9) shows the dimensionless force-displacement expression of the FPQZSI. However, it is a typical nonlinear equation, which is not convenient for the dynamic characteristic analysis.…”

“…It is shown that the quasi-zero-stiffness (QZS) isolators have the characteristics of high static-low dynamic stiffness, which can reduce the system natural frequency while ensuring its load-bearing capacity [5][6][7][8]. Then, the device isolation performance in the low frequency ranges can be greatly improved, while also having good suppression effect in the high frequency ranges [9][10]. Therefore, the QZS isolators have received increasing attention [11][12][13].…”

Vibration Isolation and Launch Performance Enhancement of the Spacecraft In-Orbit Launch Design Using the Nonlinear Dynamic Feature

“…The structure could effectively reduce the formant and expand the effective vibration isolation band due to its nonlinear stiffness and nonlinear vertical damping. Zhou et al [19] proposed a new type of passive asymmetric QZS isolator consisting of two linear springs in parallel with a negative stiffness element. Experimental results showed that the isolator had a smaller initial frequency and lower displacement transmissibility than the linear model.…”