scholarly journals Modeling a Mechanical Molecular Spring Isolator with High-Static-Low-Dynamic-Stiffness Properties

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Zhanyong Li ◽  
Qian Chen ◽  
Fengshou Gu ◽  
Andrew Ball
Keyword(s):  
Vibration Isolation ◽  
Dynamic Properties ◽  
Piecewise Linear ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Isolation System ◽  
Isolation Technique ◽  
Piston Cylinder ◽  
Low Frequency Vibration ◽  
Stiffness Model

A mechanical molecular spring isolator (MMSI) is proposed for the purpose of isolating the low-frequency vibration of a heavy payload. The MMSI is a passive vibration isolation technique mimicking molecular spring isolator characteristics of high-static-low-dynamic stiffness (HSLDS). An MMSI consists of a piston-cylinder container filled with the liquid and some hydraulic spring accumulators. The piston would support a lump of mass and be subjected to a specific external vibration excitation force. Those accumulators can get intercommunication by the liquid to produce the transformation from high static stiffness to low dynamic stiffness. The stiffness model of the MMSI with several identical accumulators is established based on the hydrostatic law. After that, some parameters that significantly influence the stiffness characteristics are studied. Results show that the stiffness property of this kind of MMSI demonstrates a piecewise linearity of three segments. It applies the averaging method to acquire amplitude-frequency and phase-frequency relationships of the piecewise linear vibration isolation system. An inevitable jump phenomenon may occur when the exciting force reaches the critical value. The vibration isolation performance is evaluated by energy transmissibility. Finally, an experimental prototype was designed to carry out quasi-static and dynamic experiments to verify the stiffness model and the dynamic properties as an HSLDS vibration isolator.

On the Effects of Mistuning a Force-Excited System Containing a Quasi-Zero-Stiffness Vibration Isolator

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Ali Abolfathi ◽  
M. J. Brennan ◽  
T. P. Waters ◽  
B. Tang
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Vibration Isolator ◽  
Linear Vibration ◽  
Vibration Isolators ◽  
Zero Dynamic ◽  
Low Frequency Vibration ◽  
Excited System ◽  
Better Than

Nonlinear isolators with high-static-low-dynamic-stiffness have received considerable attention in the recent literature due to their performance benefits compared to linear vibration isolators. A quasi-zero-stiffness (QZS) isolator is a particular case of this type of isolator, which has a zero dynamic stiffness at the static equilibrium position. These types of isolators can be used to achieve very low frequency vibration isolation, but a drawback is that they have purely hardening stiffness behavior. If something occurs to destroy the symmetry of the system, for example, by an additional static load being applied to the isolator during operation, or by the incorrect mass being suspended on the isolator, then the isolator behavior will change dramatically. The question is whether this will be detrimental to the performance of the isolator and this is addressed in this paper. The analysis in this paper shows that although the asymmetry will degrade the performance of the isolator compared to the perfectly tuned case, it will still perform better than the corresponding linear isolator provided that the amplitude of excitation is not too large.

Recent Advances in Quasi-Zero-Stiffness Vibration Isolation Systems

2013 ◽  
Vol 397-400 ◽  
pp. 295-303 ◽  
Author(s):  
Fu Niu ◽  
Ling Shuai Meng ◽  
Wen Juan Wu ◽  
Jing Gong Sun ◽  
Wei Hua Su ◽  
...  
Keyword(s):  
Vibration Isolation ◽  
Low Frequency ◽  
Future Research ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Significant Development ◽  
Recent Advances ◽  
Low Frequency Vibration ◽  
Future Research Directions ◽  
Isolation Systems

The quasi-zero-stiffness vibration isolation system has witnessed significant development due to the pressing demands for low frequency and ultra-low frequency vibration isolation. In this study, the isolation theory and the characteristic of the quasi-zero-stiffness vibration isolation system are illustrated. Based on its implementation mechanics, a comprehensive assessment of recent advances of the quasi-zero-stiffness vibration isolation system is presented. The future research directions are finally prospected.

Vibration Isolation Characteristics of Euler Strut Spring Used in Low Frequency Vibration Isolation System

2012 ◽  
Vol 248 ◽  
pp. 475-480
Author(s):  
Guan Jun Zhang ◽  
Xiang Zhu ◽  
Ran Xu ◽  
Tian Yun Li
Keyword(s):  
Vibration Isolation ◽  
Structural Parameters ◽  
Low Frequency ◽  
Resonant Frequencies ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Low Frequency Vibration ◽  
Steel Material ◽  
Internal Resonant ◽  
Spring Maximum

Recently, the Euler strut is used as the supporting spring in the low frequency isolation. An Euler spring is a column or strut of steel material which is compressed elastically beyond its buckling load, which makes the ratio of the isolated mass to the mass of the supporting spring maximum, and greatly increasing the internal resonant frequencies of the isolator. In this research, the unique mechanical properties and the expressions of the displacement transmissibility of the Euler strut are deduced. The influences of structural parameters of the strut on the stiffness and vibration isolation characteristics are investigated in detail. The results show that the Euler strut has the potential in low frequency vibration isolation, and the length and breadth of the strut can influence the stiffness, transmissibility and critical loading mass respectively.

RESEARCH ON THE INFLUENCE OF SPRING STIFFNESS IN AN ER ISOLATOR

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1635-1640
Author(s):  
JUAN WANG ◽  
SHAOHUA ZHANG
Keyword(s):  
Electric Field ◽  
Vibration Isolation ◽  
Dynamic Properties ◽  
Structural Parameters ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Spring Stiffness ◽  
Isolation System ◽  
Tunable Range ◽  
Working Principle

In this paper, the problem of Electrorheological(ER) technology's application in the vibration isolation system is empirically studied. Based on the particular characteristics of the Electrorheological Fluids (ERF) tunable damping, a metal-spring ER isolator was designed and its working principle is mainly discussed. By theoretical analysis of its simplified physical model, the dynamic response of an ER isolator is frequency- and amplitude- dependent and sensitive to structural parameters. The controllable parameters here can be the system equivalent spring stiffness K and damping coefficient C of ERF. With experiment, the exertion of ER effect was controlled through the change of K and C. Consequently, the system dynamic stiffness, which is used to describe the dynamic properties of system isolation performance, can be changed obviously. According to the dynamic performance tests, the result confirmed that applying different electric field strength could change the dynamic peculiarity of the metal-spring ER isolator. The configuration design of the ER equipment, such as stiffness ratio of two fluid chambers and the size of the electric field, which are important factors for the tunable range of ER isolator.

scholarly journals Dynamic characterization of controlled multi-channel semi-active magnetorheological fluid mount

2021 ◽  
Vol 12 (2) ◽  
pp. 751-764
Author(s):  
Zhihong Lin ◽  
Mingzhong Wu
Keyword(s):  
High Frequency ◽  
Optimization Design ◽  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Vehicle Model ◽  
Mr Fluid ◽  
Unbalanced Force ◽  
Low Frequency Vibration ◽  
Engine Mount

Abstract. In this paper, a novel structure of a controlled multi-channel semi-active magnetorheological (MR) fluid mount is proposed, including four controlled channels and one rate-dip channel. Firstly, the magnetic circuit analysis, rate-dip channel optimization design, and MR fluid mount damping analysis are given. Secondly, the mathematical model of the controlled multi-channel semi-active MR fluid mount is constructed. We analyze the effect of controlled multi-channel closing on the dynamic characteristics of the mounts and the effect of the presence or absence of the rate-dip channel on the low-frequency isolation of the mount. Finally, the controlled multi-channel semi-active MR fluid mount was applied to the 1/4 vehicle model (a model consisting of an engine, a single engine mount, a single suspension and a vehicle frame), with the transmissibility of the engine relative to the vehicle frame at low frequency and the transmissibility of the engine reciprocating unbalanced force to the vehicle frame magnitude at high frequency as the evaluation index. Numerical simulation shows the following points. (1) The controllable multi-channel semi-active MR fluid mount can achieve adjustable dynamic stiffness and damping with applied 2 A current to different channels. (2) With known external excitation source, applied currents to different controllable channels can achieve the minimum transmissibility and meet the mount wide-frequency vibration isolation requirement, while adding a rate-dip channel can improve the low-frequency vibration isolation performance of the MR fluid mount. (3) Switching and closing different controllable channels in the 1/4 vehicle model can achieve the minimum transmissibility of low-frequency engine vibrations relative to the vehicle frame and high-frequency engine vibrations reciprocating an unbalanced force to the vehicle frame. Therefore, the design of the controllable multi-channel semi-active MR fluid mount can meet the wide-frequency isolation.

scholarly journals Nonlinear Dynamic Study of Oscillation System Featuring Quasi-Zero and Asymmetric Stiffness

2021 ◽  
Author(s):  
Thanh Danh Le ◽  
Minh Ky Nguyen ◽  
Ngoc Yen Phuong Vo
Keyword(s):  
Vibration Isolation ◽  
Sliding Friction ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Force Model ◽  
Oscillation System ◽  
Time Dynamic ◽  
Bifurcation Phenomenon ◽  
Low Frequency Vibration ◽  
Approximate Polynomial

Abstract This paper will broaden our previous works about the asymmetric and quasi-zero stiffness oscillator named AQZSO. In this paper, the dynamic stiffness of the AQZSO will be investigated. Then, the condition for which the minimum dynamic stiffness is quasi-zero around the equilibrium position is also determined. By using Multi-Scale method, the fundamental resonance response of the AQZSO subjected to the vibrating base is analyzed, in which the dynamic stiffness is expressed as a fifth-order approximate polynomial through expanding Taylor series. The stability of the response is then found out via nonlinear Routh-Herwitz criterion. Moreover, because of existing the sliding friction between the cylinder and piston, the nonlinear and varying-time dynamic characteristics, the complex dynamic response of the AQZSO is the need for discovery by performing direct integration of the original dynamic equation through using 5th-order Runge-Kutta algorithm. In this work, the friction force model of cylinder will be identified through virtual prototyping technique and genetic algorithm. Additionally, the Poincáre map is also employed to analyze the bifurcation phenomenon, coexistence of multiple solutions. The traction basin of the period-1, period-2 and period-3 solution is determined, indicating that the attractor basin is influenced by the asymmetric of the stiffness curve. This research will offer a useful insight to design low frequency vibration isolation systems.

scholarly journals Design and Theoretical Analysis of High-Static-Low-Dynamic Stiffness Torsion Vibration Isolator Based on Oblique Springs

2021 ◽  
Vol 2101 (1) ◽  
pp. 012028
Author(s):  
Zhirong Yang ◽  
Lintao Li ◽  
Jiacheng Yao ◽  
Qingkai Wang
Keyword(s):  
Harmonic Balance ◽  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Vibration Isolator ◽  
Torsion Vibration ◽  
Low Frequency Vibration ◽  
Torsion Stiffness ◽  
Ihb Method ◽  
Peak Value

Abstract A torsion vibration isolator composed of oblique springs with high-static-low-dynamic stiffness (HSLDS) is proposed to attenuate the transmission of torsion vibration along the shipping shaft in this paper. It is good at in low frequency vibration isolation as it can significantly reduce the resonance frequency of the system with the same load capability. Firstly, the model of HSLDS torsion vibration isolator is introduced in this paper. Secondly, the non-dimensional torsion stiffness is formulated using mechanics theory, and the HSLDS characteristic of designed torsion vibration isolator is verified. Finally, the torque transmissibility is analyzed using the Increment Harmonic Balance (IHB) method, and the effects of the system parameters on it are analyzed. The results show that the resonant frequency increases accordingly as the stiffness ratio and the excitation torque are increased. However, the peak value of the torsion transmissibility is decreased as the damper ratio increasing.

scholarly journals Dynamics and Stability of Magnetic-air Hybrid Quasi-zero Stiffness Vibration Isolation System

2021 ◽  
Author(s):  
Youliang Jiang ◽  
Chunsheng Song ◽  
Xin Ma ◽  
Han Wu ◽  
Zhihui Mai
Keyword(s):  
Vibration Isolation ◽  
Low Frequency ◽  
Isolation Effect ◽  
Machining Accuracy ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Factors Affecting ◽  
Low Frequency Vibration ◽  
Nonlinear Mechanical ◽  
The Stability

Abstract With the improvement of machining accuracy, external low frequency vibration has become one of the most important factors affecting the performance of equipment. The theory of quasi-zero stiffness vibration isolation shows favorable low frequency vibration isolation effect. Based on our previous research on the structure of magnetic-air hybrid quasi-zero stiffness vibration isolation system, the nonlinear mechanical expression of positive and negative stiffness structure has been analyzed in this paper, to improve application of the system and provide a theoretical basis for sequential studies of active control. To analyze the judgement criterion of the quasi-zero stiffness, an accurate mechanical model was first established. Then, the dynamical model based on external low frequency vibration was developed, to investigate the stability and natural frequency and deduce the amplitude frequency characteristics and displacement transfer rate. Finally, we carried out simulation and experimental analysis to verify the stiffness of high static and low dynamic and the low frequency vibration isolation effect of the vibration isolation system.

scholarly journals Investigation of the dynamic efficiency of complex passive low-frequency vibration isolation systems

2019 ◽  
Vol 38 (2) ◽  
pp. 608-614 ◽  
Author(s):  
M Jurevicius ◽  
V Vekteris ◽  
V Turla ◽  
A Kilikevicius ◽  
G Viselga
Keyword(s):  
Vibration Isolation ◽  
Low Frequency ◽  
Experimental Investigations ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Low Frequency Vibration ◽  
Vibrating Platform ◽  
Optical Table ◽  
Narrow Frequency Range ◽  
Isolation Systems

In this study, the theoretical and experimental investigations of the dynamics of complex passive low-frequency vibration systems are described. It is shown that a complex system consisting of a vibrating platform, an optical table and a vibration isolation system of quasi-zero stiffness loaded by a certain mass may isolate low-frequency vibrations in a narrow frequency range only. In another case, the system does not isolate vibrations; it even operates as an amplifier. The frequencies that ensure the top efficiency of the vibration damping system of quasi-zero stiffness were established.

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