An innovative quasi-zero stiffness isolator with three pairs of oblique springs

Zhao, Feng; Ji, Jinchen; Ye, Kan; Luo, Quantian

doi:10.1016/j.ijmecsci.2020.106093

Cited by 126 publications

(33 citation statements)

References 48 publications

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“…e nondimensional movement range of the isolator 􏽢 d f at the critical natural frequency f c is twice the value of 􏽢 x d . By substituting equations (10) and (11) into equation ( 5), its expression can be written as follows:…”

Section: Optimization Criteria For Qzs Mechanismmentioning

confidence: 99%

“…A bioinspired nonlinear system with four linear springs arranged in a K-shaped configuration was proposed for the purpose of potential energy maximization [8]. Zhao et al [9][10][11] proposed new limb-like QZS systems with two pairs and three pairs of oblique springs to enlarge the QZS range and isolation frequency band. Similarly, Yan et al [12] proposed a large stroke QZS vibration isolator using a three-link mechanism, which is less sensitive to vibration amplitude than the traditional QZS isolator.…”

Section: Introductionmentioning

confidence: 99%

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An Improved Structural Analysis Method for Isolator with Quasi-Zero-Stiffness Characteristic

Zhang

et al. 2021

Shock and Vibration

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A typical quasi-zero-stiffness (QZS) vibration isolator consisting of a vertical spring and two oblique springs has been widely researched on its static and dynamic characteristics. A general criterion for determining structural parameters of QZS isolator is to achieve low nondimensional stiffness around the equilibrium position. However, lower nondimensional stiffness of linear isolator means lower isolation frequency, which may be invalid on QZS isolator. Because there is an implicit relationship between geometric parameter and stiffness ratio of QZS isolator, this study presents an improved optimization criterion for determining the optimal structural parameters of the typical QZS isolator. The optimization criterion is that the QZS isolator has the maximum displacement range around the equilibrium position without exceeding given natural frequency, rather than given nondimensional stiffness. The results show that isolator with these optimal parameters can achieve lower stiffness around the equilibrium position and better vibration isolation performance. Furthermore, an extended QZS isolator consisting of vertical spring with fixed stiffness and prestressed oblique springs is discussed to further improve stiffness characteristic. Better stiffness performance can be obtained when the prestressed oblique springs have softening stiffness and the exponent of the nonlinear stiffness is 2. Considering the existence of friction in practical application, the influence of friction on both static and dynamic characteristics is investigated. The analysis reveals that friction has little influence on its stiffness characteristic around the static equilibrium position and friction damping produced by friction affects the response amplitude and resonant frequency in dynamics.

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Section: Optimization Criteria For Qzs Mechanismmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An Improved Structural Analysis Method for Isolator with Quasi-Zero-Stiffness Characteristic

Zhang

et al. 2021

Shock and Vibration

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show abstract

“…Gatti [11] arranged four linear springs inclined and symmetrically for vibration isolation. Inspired by the structure of the bionic limb, Zhao et al [12] combined three pairs of oblique springs with vertical springs in parallel to form a novel QZS isolator. Subsequently, the cam-rollerspring mechanism [13][14][15] was further studied.…”

Section: Introductionmentioning

confidence: 99%

Design and Analysis of a Novel Quasi-Zero Stiffness Isolator under Variable Loads

Xie¹,

Niu²,

Sun³

et al. 2022

Mathematical Problems in Engineering

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The designed load of most quasi-zero stiffness (QZS) isolators is constant. The isolation performance will drop sharply once the load changes. A novel QZS isolator that can adapt to variable loads is proposed in this paper to improve the range of application of the isolator. The isolator is designed by paralleling the electromagnetic spring (ES), which provides negative stiffness, and the pneumatic spring (PS), which provides positive stiffness. The positive and negative stiffness can be adjusted by changing the pressure and coil current, which provides the possibility for the isolator to adapt to variable loads. This paper derived the conditions for the isolation system to obtain QZS characteristics, proposed the dynamic model of the isolation system, derived and verified the analytical expressions of the amplitude-frequency response and force transmissibility (FT), and discussed the change of FT and displacement transmissibility(DT) under different loads. Theoretical analysis shows that changing the pressure and coil current in the same proportion can maintain the superior low-frequency isolation performance when the load changes, thanks to the preservation of the QZS characteristics of the system after adjusting the pressure and coil current. Finally, the simulation results fg and isolation frequency band over the linear isolation system and PS isolation system. Furthermore, the proposed isolator can be adjusted online.

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“…The QZS isolators have higher static support capacity and lower dynamic stiffness near the static equilibrium position compared with passive isolators, which can reduce system natural frequency and improve the low-frequency isolation effect. Most of the QZS isolators are obtained by paralleling the mechanism that provides negative stiffness and the spring, such as the oblique springs [1][2][3] and the cam-roller mechanisms [4][5][6] . However, it is difficult for them to cope with the change of load and control.…”

Section: Introductionmentioning

confidence: 99%

Fuzzy PID Control of Nonlinear Vibration Isolator with Parallel Electromagnetic Negative Stiffness

Xie

Niu

Meng

et al. 2022

J. Phys.: Conf. Ser.

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A fuzzy PID control strategy for quasi-zero stiffness (QZS) isolator which connects the pneumatic spring (PS) and the electromagnetic negative stiffness mechanism (ENSM) in parallel to suppress low-frequency vibration is proposed in this paper. First, the restoring force of PS and the electromagnetic force of the ENSM are derived. Secondly, the static analysis of the isolation system is carried out, and the analytical expressions of stiffness and restoring force of the vibration isolation system is obtained. The possibility of the vibration isolator reaching the QZS state is explained. Then, to obtain a better isolation effect, the optimal current of the coil is found according to the designed fuzzy PID control strategy. Finally, the simulation result shows that the isolation frequency band of the isolation system under fuzzy PID control and PID control is widened, and the vibration isolation performance under fuzzy PID control reaches more than 85% under different excitation frequencies. Control effect and vibration isolation performance under fuzzy PID control are better.

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An innovative quasi-zero stiffness isolator with three pairs of oblique springs

Cited by 126 publications

References 48 publications

An Improved Structural Analysis Method for Isolator with Quasi-Zero-Stiffness Characteristic

An Improved Structural Analysis Method for Isolator with Quasi-Zero-Stiffness Characteristic

Design and Analysis of a Novel Quasi-Zero Stiffness Isolator under Variable Loads

Fuzzy PID Control of Nonlinear Vibration Isolator with Parallel Electromagnetic Negative Stiffness

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