Vibration isolation of lumped masses supported on beam subjected to varying excitation frequency by imposing node method

2019 ◽  
pp. 1-13 ◽  
Author(s):  
Sushil S Patil
Keyword(s):  
Vibration Isolation ◽  
Excitation Frequency ◽  
Lumped Masses

Study on the Application of Damping Control Method in Multi-Solution Interval of the QZS System

2013 ◽  
Vol 457-458 ◽  
pp. 1017-1020
Author(s):  
Qing Chao Yang ◽  
Jing Jun Lou ◽  
Ai Min Diao
Keyword(s):  
Small Amplitude ◽  
Vibration Isolation ◽  
Control Method ◽  
Excitation Frequency ◽  
Main Idea ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Damping Control ◽  
Controlling System ◽  
Vibration Attenuation

The quasi-zero-stiffness system (QZS) is a nonlinear vibration isolation system, when the excitation frequency is in the multi-solution domain, the system may malfunctions in vibration attenuation. To solve this problem, the damping control method is introduced in this paper. The main idea is that the response on the resonance branch with large amplitude can switches to the non-resonance branch with small amplitude by controlling system damping, and it can stay on the non-resonance branch in the next process, which makes vibration isolation is also available in this interval. During this process, the Van den Pol plane is used to determine the time of which damping control can be withdrawn.

Vibration Analysis of Nonlinear Isolator’s Characteristics by ADAMS

2012 ◽  
Vol 152-154 ◽  
pp. 1077-1081 ◽  
Author(s):  
Zhao Qi He ◽  
Yu Chao Song ◽  
Hong Liang Yu
Keyword(s):  
Nonlinear Vibration ◽  
Vibration Isolation ◽  
Excitation Frequency ◽  
Vibration Isolator ◽  
Vibration System ◽  
Linear Vibration ◽  
External Excitation ◽  
Mass Model ◽  
Adams Software ◽  
Isolation Systems

A nonlinear spring-mass model is established to study the dynamic characteristics of nonlinear vibration isolator. By use of ADAMS software, the influence of stiffness, foundation displacement excitation and frequency of external excitation on the nonlinear vibration isolation systems are analyzed. Results indicate that the linear vibration system needs 4s to achieve stability, but the nonlinear vibration system only needs 0.1s. The response value increases with the increase of excitation frequency, the response pick value increases by 61.58% and 102.35% and each corresponding stable value increases by 159.35% and 309.87%.

Dynamic Analysis of Bionic Vibration Isolation Platform Based on Viscoelastic Materials

2014 ◽  
Vol 852 ◽  
pp. 467-471
Author(s):  
Hong Qing Lv ◽  
Wei Xiao Tang ◽  
Qing Hua Song
Keyword(s):  
Vibration Isolation ◽  
Excitation Frequency ◽  
Viscoelastic Damper ◽  
Physical Damage ◽  
Isolation System ◽  
Rubber Layer ◽  
Environmental Vibration ◽  
Performance Deterioration ◽  
Nonlinear Dynamics Model ◽  
Stiffness And Damping

The ecological structures of some organisms that could resist environmental vibration naturally (such as dragonfly, woodpecker and legs of cursorial animals) uncovered by biologists inspire people a new approach to overcome the above problem. In this paper, a new shock isolation system consisting of a pedestal, a rubber layer, an air spring and a shearing viscoelastic damper is designed, fabricated, and characterized to avoid the performance deterioration and physical damage of mechanical manufacturing devices from external mechanical excitations. The nonlinear dynamics model of the platform is developed and the dynamic characteristics are analyzed using numerical analysis. The displacement and velocity response are obtained. The results demonstrate that the stiffness and damping characteristic of the platform change with excitation frequency. The vibration isolation effectiveness will be greatly enhanced.

Tests and Modeling of a New Vibration Isolation and Suppression Device

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Zhao-Dong Xu ◽  
Yeshou Xu ◽  
Qianqiu Yang ◽  
Chao Xu ◽  
Feihong Xu ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Energy Dissipation ◽  
Viscoelastic Material ◽  
Vibration Isolation ◽  
Dynamic Properties ◽  
Excitation Frequency ◽  
Dynamic Responses ◽  
Damping Capacity ◽  
Air Spring ◽  
Energy Dissipation Devices

Vibration is an environmental factor with hazardous effects on the instruments' precision, structural stability, and service life in engineering fields. Many kinds of energy dissipation devices have been invented to reduce the dynamic responses of structures and instruments due to environmental excitations. In this paper, a new kind of vibration isolation and suppression device with high damping performance, fine deformation recoverability, and bearing capacity for platform structures is developed, which is designed by considering the combination of the energy dissipation mechanisms of viscoelastic material, viscous fluid, and air spring. A series of dynamic properties tests on the device are carried out under different excitation frequencies and displacement amplitudes, and a mathematical model considering the coupling effects of energy dissipation of viscoelastic material, viscous liquid, and air spring is proposed. The research results indicate that the vibration isolation and suppression device has high damping capacity, and the proposed mathematical model can well describe the mechanical properties affected by excitation frequency and displacement amplitude.

Analysis and Experiment of an Air Vibration Isolation System with Auxiliary Chambers

2012 ◽  
Vol 226-228 ◽  
pp. 195-198
Author(s):  
Rong Wei Wen ◽  
Jiu Bin Tan ◽  
Lei Wang ◽  
Guan Hua Wang
Keyword(s):  
Resonant Frequency ◽  
Vibration Isolation ◽  
Excitation Frequency ◽  
Volume Ratio ◽  
Air Spring ◽  
Working Pressure ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Vibration Transmissibility ◽  
System Vibration

A mathematical model of a single degree of freedom air spring vibration isolation system is established. The model analyzes the influence of structural damping in the air spring vibration isolation system based on the traditional model. This paper establishes the relationship between the working pressure p, the volume ratio of n and system vibration transmissibility T under forced vibration. The experimental results are verified on different working pressure. The results showed that working pressure p has little effect on the resonant frequency of the system and the system vibration transmissibility. The smaller the ratio n, the lower the resonant frequency of the system and the system vibration transmissibility. The environmental excitation frequency range must be taken into account in designing.

Experimental Study of the Variable Stiffness Vibration Isolator

2011 ◽  
Vol 328-330 ◽  
pp. 2129-2133 ◽  
Author(s):  
Zhi Jun Shuai ◽  
Tie Jun Yang ◽  
Zhuo Liang Zhou ◽  
Zhi Gang Liu
Keyword(s):  
Natural Frequency ◽  
Vibration Isolation ◽  
Excitation Frequency ◽  
Low Frequency ◽  
Variable Stiffness ◽  
Resonance Problem ◽  
Vibration Isolator ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Passive Vibration Isolation

The traditional passive vibration isolation system can reduce the vibration transmission greatly while the excitation frequency is times higher than its natural frequency. As the external excitation approach its natural frequency, vibration isolator system is invalid. In this paper, a new variable stiffness vibration isolator was designed to solve the low-frequency resonance problem of the traditional isolator by combining toothed electromagnetic spring with passive isolator. Theoretical analysis and experimental results illustrate that this isolator met the design requirements and obtained the no resonance operating characteristic at the low frequency.

scholarly journals A New Approach to Achieve Variable Negative Stiffness by Using an Electromagnetic Asymmetric Tooth Structure

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Chao Han ◽  
Xueguang Liu ◽  
Muyun Wu ◽  
Weilong Liang
Keyword(s):  
Vibration Isolation ◽  
Excitation Frequency ◽  
Negative Stiffness ◽  
Vibration Isolator ◽  
Linear Vibration ◽  
Excellent Performance ◽  
New Approach ◽  
Tooth Structure ◽  
Vibration Isolators ◽  
Electromagnetic Vibration

Traditional passive nonlinear isolators have been paid much attention in recent literatures due to their excellent performance compared to linear vibration isolators. However, they are incapable of dealing with varying conditions such as changing excitation frequency due to the nonadjustable negative stiffness. To solve this drawback, a new approach to achieve variable negative stiffness is proposed in this paper. The negative stiffness is realized by an electromagnetic asymmetric magnetic tooth structure and can be changed by adjusting the magnitude of the input direct current. Analytical model of the electromagnetic force is built and simulations of magnetic field are conducted to validate the negative stiffness. Then the EATS is applied to vibration isolation and an electromagnetic vibration isolator is designed. Finally, a series of tests are conducted to measure the negative stiffness experimentally and confirm the effect of the EATS in vibration isolation.

scholarly journals Stability and convergence analysis for different harmonic control algorithm implementations

2015 ◽  
Vol 23 (8) ◽  
pp. 1231-1247 ◽  
Author(s):  
Ilias Zazas ◽  
Steve Daley
Keyword(s):  
Stability Analysis ◽  
Vibration Isolation ◽  
Closed Loop ◽  
Linear Time ◽  
Excitation Frequency ◽  
Stability And Convergence ◽  
Speed Of Convergence ◽  
Harmonic Control ◽  
Disturbance Frequency ◽  
Loop Stability

In many engineering systems there is a common requirement to isolate the supporting foundation from low frequency periodic machinery vibration sources. In such cases the vibration is mainly transmitted at the fundamental excitation frequency and its multiple harmonics. It is well known that passive approaches have poor performance at low frequencies and for this reason a number of active control technologies have been developed. For discrete frequencies disturbance rejection Harmonic Control (HC) techniques provide excellent performance. In the general case of variable speed engines or motors, the disturbance frequency changes with time, following the rotational speed of the engine or motor. For such applications, an important requirement for the control system is to converge to the optimal solution as rapidly as possible for all variations without altering the system's stability. For a variety of applications this may be difficult to achieve, especially when the disturbance frequency is close to a resonance peak and a small value of convergence gain is usually preferred to ensure closed-loop stability. This can lead to poor vibration isolation performance and long convergence times. In this paper, the performance of two recently developed HC algorithms are compared (in terms of both closed-loop stability and speed of convergence) in a vibration control application and for the case when the disturbance frequency is close to a resonant frequency. In earlier work it has been shown that both frequency domain HC algorithms can be represented by Linear Time Invariant (LTI) feedback compensators each designed to operate at the disturbance frequency. As a result, the convergence and stability analysis can be performed using the LTI representations with any suitable method from the LTI framework. For the example mentioned above, the speed of convergence provided by each algorithm is compared by determining the locations of the dominant closed-loop poles and stability analysis is performed using the open-loop frequency responses and the Nyquist criterion. The theoretical findings are validated through simulations and experimental analysis.

scholarly journals Ultra-Wide Bandgap in Two-Dimensional Metamaterial Embedded with Acoustic Black Hole Structures

2021 ◽  
Vol 11 (24) ◽  
pp. 11788
Author(s):  
Xiaofei Lyu ◽  
Qian Ding ◽  
Zhisai Ma ◽  
Tianzhi Yang
Keyword(s):  
Cell Wall ◽  
Black Hole ◽  
Vibration Isolation ◽  
Hexagonal Lattice ◽  
Wide Bandgap ◽  
Vibration Modes ◽  
Practical Application ◽  
Equipment Development ◽  
Lumped Masses ◽  
Local Stiffness

This paper reports a type of metamaterial plate enabling in-plane ultra-wide vibration isolation in engineering equipment development. It is composed of periodic hexagonal lattice structures. The acoustic black hole (ABH) structures are embedded in each cell wall of the conventional hexagonal lattice, which results in the reduction of local stiffness in the cell wall and the local mass in the hexagonal corner. The lattice can be simplified as the form of lumped masses vibrating on springs, and two types of eigenstates can be obtained: the rotational eigenstates and the transverse eigenstates. The geometric nonlinearity of the ABH structure leads to unevenly distributed vibration modes, resulting in the ultra-wide bandgap. Experimental results prove the effective attenuation capacity. Compared with the traditional hexagonal lattice, the proposed design provides greater advantages in practical application.

Design of smart machinery installations to reduce transmitted vibrations by adaptive modification of internal forces

1998 ◽  
Vol 212 (3) ◽  
pp. 215-228 ◽  
Author(s):  
T Long ◽  
M J Brennan ◽  
S J Elliott
Keyword(s):  
Vibration Isolation ◽  
Excitation Frequency ◽  
Open Loop ◽  
Operating Conditions ◽  
Coupled Resonators ◽  
Loop Control ◽  
Tunable Resonators ◽  
Vibration Attenuation ◽  
Feasible Option ◽  
Internal Forces

There is a requirement to isolate machinery from their surroundings to reduce the transmission of noise and vibration. Reducing the input disturbance of a system can reduce vibration levels, but this is not always a feasible option. One of the simplest ways to overcome these problems is to retrofit a vibration attenuation device. The method used for vibration isolation discussed in this paper is semi-active control and involves using tunable resonators at the mounting positions. These resonators operate by continually adjusting their characteristics such that a large force is generated, achieving vibration attenuation over a range of varying operating conditions. In this paper, the resonators are tuned such that the natural frequency of the resonator is equal to the excitation frequency. Open-loop control is used to roughly tune the resonator, with a precise algorithm changing the characteristics of the resonator such that the host structure and resonator are in quadrature. Using multiple resonators increases the complexity of the system as interaction is possible between the resonators. The interaction between well-coupled resonators is modelled and examined experimentally. A simple control algorithm is developed and implemented which demonstrates that the resonators can be tuned independently, irrespective of the dynamic coupling between them.

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