A Study of a Pendulum-Like Vibration Isolator With Quasi-Zero-Stiffness

2021 ◽  
Author(s):  
Yishen Tian ◽  
Dengqing Cao ◽  
Yan Wang
Keyword(s):  
Harmonic Balance ◽  
Geometric Nonlinearity ◽  
Harmonic Balance Method ◽  
The Novel ◽  
Vibration Isolator ◽  
Frequency Range ◽  
Jump Phenomenon ◽  
Isolation Performance ◽  
Force And Displacement Transmissibility ◽  
Better Than

Abstract This article introduces a pendulum element to a 3-spring vibration isolator to achieve a high-static-low-dynamic (HSLD) stiffness or even quasi-zero stiffness (QZS) around the equilibrium position. Numerical simulation is given and the harmonic balance method (HBM) is used to obtain time responses for analysis. Effects of different parameters on the isolation performance are studied and summarized. Approximation force and displacement transmissibility of the system are calculated to evaluate the isolation performance. Comparisons are made with those of an equivalent linear isolator and the typical 1 degree-of-freedom (DOF) QZS isolator. Results show that the novel vibration isolator performs better than existing isolators under selected parameters. The left bent backbone of the novel isolator demonstrates evident softening geometric nonlinearity. Therefore, it achieves a wider frequency range of isolation than the linear 1DOF isolator and typical 3-spring QZS isolator. Moreover, the transmissibility of the novel isolator is smaller at higher frequencies as the jump phenomenon occurs on the left.

Design and Dynamic Characteristics of a Torsion Isolator With Negative Stiffness Structures

2016 ◽  
Author(s):  
Hui Liu ◽  
Xiaojie Wang ◽  
Weida Wang ◽  
Changle Xiang
Keyword(s):  
Harmonic Balance ◽  
Vibration Isolation ◽  
Harmonic Balance Method ◽  
Negative Stiffness ◽  
Frequency Range ◽  
Disk Structure ◽  
Vibration Transmissibility ◽  
Low Stiffness ◽  
Vibration Isolation Performance ◽  
Isolation Performance

This paper proposes a torsion isolator with negative stiffness structures, which has low stiffness. The torsion isolator has been designed into disk structure, which is the installation position of the positive springs and negative stiffness structures. In this paper, the model of the torsion isolator is introduced firstly, and the nonlinear stiffness and torque are studied under different compression deformation of springs in negative stiffness structures. Then a two-degree-freedom equation of the torsional isolator is established and vibration transmissibility is obtained by using Harmonic Balance Method. Theoretical analysis results show that the isolator with negative stiffness structures has larger isolation frequency range than linear isolator. Finally, an initial experiment is completed. The experimental results show that the isolator has a good vibration isolation performance.

Beneficial performance of a quasi-zero stiffness vibration isolator with generalized geometric nonlinear damping

2020 ◽  
pp. 095745652097238
Author(s):  
Chun Cheng ◽  
Ran Ma ◽  
Yan Hu
Keyword(s):  
Damping Ratio ◽  
Nonlinear Damping ◽  
Vibration Isolator ◽  
Equivalent Damping ◽  
Frequency Responses ◽  
Geometric Nonlinear ◽  
Resonant Region ◽  
Force Transmissibility ◽  
Isolation Performance ◽  
Force And Displacement Transmissibility

Generalized geometric nonlinear damping based on the viscous damper with a non-negative velocity exponent is proposed to improve the isolation performance of a quasi-zero stiffness (QZS) vibration isolator in this paper. Firstly, the generalized geometric nonlinear damping characteristic is derived. Then, the amplitude-frequency responses of the QZS vibration isolator under force and base excitations are obtained, respectively, using the averaging method. Parametric analysis of the force and displacement transmissibility is conducted subsequently. At last, two phenomena are explained from the viewpoint of the equivalent damping ratio. The results show that decreasing the velocity exponent of the horizontal damper is beneficial to reduce the force transmissibility in the resonant region. For the case of base excitation, it is beneficial to select a smaller velocity exponent only when the nonlinear damping ratio is relatively large.

Non-resonant response of the novel airborne photoelectric quasi-zero stiffness platform with friction damping

2020 ◽  
Vol 64 (1-4) ◽  
pp. 315-324
Author(s):  
Guangxu Dong ◽  
Chicheng Ma ◽  
Feng Zhang ◽  
Yajun Luo ◽  
Chuanxing Bi
Keyword(s):  
Current Model ◽  
Excitation Frequency ◽  
Low Frequency ◽  
Harmonic Balance Method ◽  
Negative Stiffness ◽  
The Novel ◽  
Friction Damping ◽  
Improve Measurement ◽  
Photoelectric System ◽  
Isolation Performance

To suppress the low frequency vibrations of airborne photoelectric system and improve measurement accuracy, a novel passive airborne photoelectric quasi-zero stiffness platform (APQZSP), which is composed of upper/bottom planes, anti-shaking structure and six quasi-zero stiffness (QZS) legs, is designed. The QZS leg is constructed by connecting the folded beam spring with magnetic negative stiffness spring (MNSS) in parallel. According to current model, the magnetic force and negative stiffness of MNSS are derived. As the friction damping is introduced with anti-shaking structure, the isolation performance of the platform under friction damping is investigated based on harmonic balance method. Then the effect of damping and excitation on the isolation performance is analyzed. The results indicate that with the QZS technology, the resonant frequency of the platform is reduced and the low frequency vibrations can be effectively isolated with APQZSP. Moreover, the friction damping can maintain the displacement transmissibility at unity as long as the excitation frequency is lower than the break-loose frequency, and then the resonance can be avoided.

Feasibility Research on Coupled Friction/Piezoelectric Dampers

2018 ◽  
Author(s):  
Lin Li ◽  
Yaguang Wu ◽  
Yu Fan
Keyword(s):  
Dry Friction ◽  
Harmonic Balance ◽  
Vibrational Mode ◽  
Piezoelectric Materials ◽  
Harmonic Balance Method ◽  
Forced Response ◽  
Friction Dampers ◽  
Feasibility Research ◽  
Aero Engines ◽  
Better Than

A new passive damper coupling the energy dissipative mechanisms of dry friction and piezoelectric shunting circuit is proposed. The idea is to embed the shunted piezoelectric materials to the dry friction dampers at appropriate positions, so that the elastic deformation of the dry friction dampers can be utilized to generate additional damping. Moreover, this provides a more practical way to install the piezoelectric dampers into realistic mechanical systems such as aero-engines. A five Degree-of-freedom (DOFs) lumped system model is introduced to demonstrate the feasibility of such an idea. The damping performance is revealed using the forced response results obtained by the Multi Harmonic Balance Method (MHBM). We show that the coupled damper significantly outperforms the standalone piezoelectric or dry friction dampers. The coupled damper is better than, at least equivalent to, the case where both piezoelectric and dry friction dampers are applied but in uncoupled manner. Eventually, the mechanism of the proposed damper is further explained from the perspective of vibrational mode and energy conversion.

scholarly journals An Asymmetric Quasi-zero Stiffness Vibration Isolator with Long Stroke and Large Bearing Capacity

2021 ◽  
Author(s):  
Xinghua Zhou ◽  
Dingxuan Zhao ◽  
Xiao Sun ◽  
Xiao Yang ◽  
Jianhai Zhang ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Vibration Isolation ◽  
Geometrical Nonlinearity ◽  
Harmonic Balance Method ◽  
Nonlinear Damping ◽  
Vibration Isolator ◽  
Plate Spring ◽  
Supporting Force ◽  
Vibration Isolation Performance ◽  
Isolation Performance

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 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.

COALESCENCE OF THE TWO SECONDARY RESPONSES IN COUPLED DUFFING EQUATIONS

2012 ◽  
Vol 22 (06) ◽  
pp. 1250149
Author(s):  
TING-YU LAI ◽  
PI-CHENG TUNG ◽  
YUNG-CHIA HSIAO
Keyword(s):  
Periodic Orbits ◽  
Harmonic Balance ◽  
Shooting Method ◽  
Harmonic Balance Method ◽  
The Novel ◽  
Duffing Equations ◽  
Duffing System ◽  
Parametric Continuation ◽  
Continuation Algorithm ◽  
The Stability

The novel coalescence of the secondary responses for the coupled Duffing equations are observed in this study. Two secondary responses that do not bifurcate from the primary responses merge into one due to saddle-node bifurcation generation within a specific parameter range. The frequency responses of the coupled Duffing equations are calculated using the harmonic balance method while the periodic orbits are detected by the shooting method. The stability of the periodic orbits is determined on utilizing Floquet theory. The parametric continuation algorithm is used to obtain the bifurcation points and bifurcation lines for a Duffing system with two varying parameters. The analytical results demonstrate the novel phenomenon that occurs in the Duffing equations.

On the Modeling and Optimization of Anti-Vibration Gloves for Hand-Arm Vibration Control

2019 ◽  
Author(s):  
Sunit K. Gupta ◽  
Oreoluwa Alabi ◽  
Paul-Camille Kakou ◽  
Oumar Barry
Keyword(s):  
Mechanical Model ◽  
Harmonic Balance ◽  
Parametric Analysis ◽  
Harmonic Balance Method ◽  
Analytical Models ◽  
Human Hand ◽  
Frequency Range ◽  
Hand Tools ◽  
Hand Tool ◽  
Linear Spring

Abstract Various studies in hand-arm vibrations have shown that isolators in the form of anti-vibration (AV) gloves are effective to reduce unwanted vibrations, transmitted to the human hand, from machines and hand tools. However, most of these studies are based on experimental or numerical analysis and hence, the level of effectiveness and optimum values of the glove’s properties remain unclear. In this work, we analytically study the dynamics of hand-arm vibrations with and without a glove using the harmonic balance method. The considered analytical models for the hand-arm vibration comprise of lumped multi-degree of freedom system. The hand-tool interactions are modeled as linear spring and damper system for simplicity and accordingly, we obtain the equations governing the dynamics of the human-hand system. We perform parametric analysis using this bio-mechanical model of the hand-arm vibrations with and without a glove. The parametric analysis on the relative transmissibility (i.e., the ratio of transmissibilities with glove to without glove) shows the dependence of the transmissibility on the glove parameters. We observe that the effect of glove parameters on the relative transmissibility is not monotonous for the studied frequency range. This observation further motivates us to perform optimization of the glove parameters to minimize the overall transmissibility.

Adaptive Microslip Projection for Reduction of Frictional and Contact Nonlinearities in Shrouded Blisks

2016 ◽  
Vol 11 (4) ◽  
Author(s):  
Mainak Mitra ◽  
Stefano Zucca ◽  
Bogdan I. Epureanu
Keyword(s):  
Harmonic Balance ◽  
Coulomb Friction ◽  
Degrees Of Freedom ◽  
Harmonic Balance Method ◽  
The Novel ◽  
Contact Interface ◽  
Baseline Model ◽  
Stick Slip ◽  
Reduced Order ◽  
Novel Method

Reduced order models (ROMs) of turbine bladed disks (blisks) are essential to quickly yet accurately characterize vibration characteristics and effectively design for high cycle fatigue. Modeling blisks with contacting shrouds at adjacent blades is especially challenging due to friction damping and localized nonlinearities at the contact interfaces which can lead to complex stick–slip behavior. While well-known techniques such as the harmonic balance method (HBM) and Craig–Bampton component mode synthesis (CB-CMS) have generally been employed to generate ROMs in the past, they do not reduce degrees-of-freedom (DoFs) at the interfaces themselves. In this paper, we propose a novel method to obtain a set of reduction basis functions for the contact interface DoFs as well as the remaining DoFs called “adaptive microslip projection” (AMP). The method is based on analyzing a set of linear systems with specifically chosen boundary conditions on the contact interface. Simulated responses of full order baseline models and the novel ROMs under various conditions are studied. Results obtained from the ROMs compare very favorably with the baseline model. This study addresses the case of a shrouded blisk in microslip close to stick. The AMP procedure may be possibly applied to other systems with Coulomb friction contacts, but its accuracy and effectiveness will need to be evaluated separately.

Adaptive Microslip Projection (AMP) for Reduction of Frictional and Contact Non-Linearities in Shrouded Blisks

2015 ◽  
Author(s):  
Mainak Mitra ◽  
Stefano Zucca ◽  
Bogdan I. Epureanu
Keyword(s):  
Harmonic Balance ◽  
Coulomb Friction ◽  
Degrees Of Freedom ◽  
Harmonic Balance Method ◽  
The Novel ◽  
Contact Interface ◽  
Baseline Model ◽  
Stick Slip ◽  
Reduced Order ◽  
Novel Method

Reduced order models (ROMs) of turbine bladed disks (blisks) are essential to quickly yet accurately characterize vibration characteristics and effectively design for high cycle fatigue. Modeling blisks with contacting shrouds at adjacent blades is especially challenging due to friction damping and localized non-linearities at the contact interfaces which can lead to complex stick-slip behavior. While well-known techniques such as the harmonic balance method and Craig-Bampton component mode synthesis have generally been employed to generate ROMs in the past, they do not reduce degrees of freedom (DoFs) at the interfaces themselves. In this paper we propose a novel method to obtain a set of reduction basis functions for the contact interface DoFs as well as the remaining DoFs called adaptive microslip projection (AMP). The method is based on analyzing a set of linear systems with specifically chosen boundary conditions on the contact interface. Simulated responses of full order baseline models and the novel ROMs under various conditions are studied. Results obtained from the ROMs compare very favorably with the baseline model. The AMP procedure is also easily generalizable to other dynamic systems with Coulomb friction contacts.

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