Analytical Study of Vibration Isolation Between a Pair of Flexible Structures

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
G. T. Zheng ◽  
Y. Q. Tu
Keyword(s):  
Vibration Isolation ◽  
Coupling Effect ◽  
Flexible Structures ◽  
Flexible Structure ◽  
Vibration Attenuation ◽  
Vibration Transmissibility ◽  
Proper Design ◽  
Structure Vibration ◽  
Flexible Foundation ◽  
Isolation Performance

The problem of flexible structure vibration isolation on a flexible foundation is analytically investigated by simplifying the vibration isolation as single axis isolation, which can be realized by a proper design, and the problem of the whole spacecraft vibration is taken as an example for the application as both the spacecraft (isolated structure) and the launch vehicle (foundation) are flexible structures. A numerical example of the whole spacecraft vibration isolation is also provided for further explaining those conclusions derived from the analytical studies. It is found from the study that the isolator’s damping is important for attenuating the vibration and that weakening the isolator’s stiffness has the same effect as increasing its damping. However, a weaker stiffness means a weaker coupling among the structures and may magnify the vibration at some resonant frequencies, which are close to those of individual structures. The coupling effect of the structure’s flexibility on the isolation may be significant in some cases and a coupling analysis is essential for ensuring the isolation performance. Because of the importance of the isolator’s damping in reducing the vibration transmissibility and the vibration of the coupled structure, it is more appropriate to describe the vibration isolation of the flexible structure as vibration attenuation.

On the Vibration Isolation of Flexible Structures

2006 ◽  
Vol 74 (3) ◽  
pp. 415-420 ◽  
Author(s):  
Y. Q. Tu ◽  
G. T. Zheng
Keyword(s):  
Vibration Isolation ◽  
Flexible Structures ◽  
Vibration Absorber ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Isolation Frequency ◽  
Vibration Attenuation ◽  
Vibration Transmissibility ◽  
Structure Vibration ◽  
Modal Space

Although the study of vibration isolation has a very long history, when an isolated structure is so flexible that it cannot be properly approximated with a rigid body or a single-degree-of-freedom model, its vibration isolation brings about some new questions and problems. By transforming the dynamic equation of motion of the coupled structure formed by the isolator and the isolated structure into the modal space and following the tradition of studying features of the vibration transmissibility across the isolator, questions and problems associated with the flexible structure vibration isolation are studied. It is found from the study that a lower isolation frequency and a higher damping level can both increase the isolation effectiveness, the isolated structure is a vibration absorber to the isolator, and a combination of the vibration isolation and the vibration attenuation can be more effective in mitigating the vibration. A numerical example of the whole spacecraft vibration isolation has proved the above conclusions.

An hourglass-type electromagnetic isolator with negative resistance electromagnetic shunt circuit

2020 ◽  
Vol 64 (1-4) ◽  
pp. 549-556
Author(s):  
Yajun Luo ◽  
Linwei Ji ◽  
Yahong Zhang ◽  
Minglong Xu ◽  
Xinong Zhang
Keyword(s):  
Vibration Isolation ◽  
Electromechanical Coupling ◽  
Coupling Effect ◽  
Negative Resistance ◽  
Isolation System ◽  
Amplitude Vibration ◽  
Vibration Responses ◽  
The Stability ◽  
Isolation Performance ◽  
Shunt Circuit

The present work proposed an hourglass-type electromagnetic isolator with negative resistance (NR) shunt circuit to achieve the effective suppression of the micro-amplitude vibration response in various advanced instruments and equipment. By innovatively design of combining the displacement amplifier and the NR electromagnetic shunt circuit, the current new type of vibration isolator not only can effectively solve the problem of micro-amplitude vibration control, but also has significant electromechanical coupling effect, to obtain excellent vibration isolation performance. The design of the isolator and motion relationship is presented firstly. The electromechanical coupling dynamic model of the isolator is also given. Moreover, the optimal design of the NR electromagnetic shunt circuit and the stability analysis of the vibration isolation system are carried out. Finally, the simulation results about the transfer function and vibration responses demonstrated that the isolator has a significant isolation performance.

Energy flow and performance evaluation of inerter-based vibration isolators mounted on finite and infinite flexible foundation structures

2022 ◽  
Vol 14 (1) ◽  
pp. 168781402110704
Author(s):  
Zhuang Dong ◽  
Jian Yang ◽  
Chendi Zhu ◽  
Dimitrios Chronopoulos ◽  
Tianyun Li
Keyword(s):  
Power Flow ◽  
Vibration Isolation ◽  
Vibration Suppression ◽  
Flow Behavior ◽  
Flexible Beam ◽  
Vibration Isolators ◽  
Force Transmissibility ◽  
And Performance ◽  
Flexible Foundation ◽  
Isolation Performance

This study investigates the vibration power flow behavior and performance of inerter-based vibration isolators mounted on finite and infinite flexible beam structures. Two configurations of vibration isolators with spring, damper, and inerter as well as different rigidities of finite and infinite foundation structures are considered. Both the time-averaged power flow transmission and the force transmissibility are studied and used as indices to evaluate the isolation performance. Comparisons are made between the two proposed configurations of inerter-based isolators and the conventional spring-damper isolators to show potential performance benefits of including inerter for effective vibration isolation. It is shown that by configuring the inerter, spring, and damper in parallel in the isolator, anti-peaks are introduced in the time-averaged transmitted power and force transmissibility at specific frequencies such that the vibration transmission to the foundation can be greatly suppressed. When the inerter is connected in series with a spring-damper unit and then in-parallel with a spring, considerable improvement in vibration isolation can be achieved near the original peak frequency while maintaining good high-frequency isolation performance. The study provides better understanding of the effects of adding inerters to vibration isolators mounted on a flexible foundation, and benefits enhanced designs of inerter-based vibration suppression systems.

On vibration isolation of sandwich plate with periodic hollow tube core

2017 ◽  
Vol 21 (3) ◽  
pp. 1119-1132 ◽  
Author(s):  
Gui-Lan Yu ◽  
Hong-Wei Miao
Keyword(s):  
Vibration Isolation ◽  
Sandwich Plate ◽  
Experimental Studies ◽  
Low Frequency ◽  
Dispersion Relations ◽  
Frequency Responses ◽  
Vibration Attenuation ◽  
Potential Applications ◽  
Vibration Isolation Performance ◽  
Isolation Performance

The vibration isolation performance of a PC sandwich plate with periodic hollow tube core is investigated experimentally and numerically. The experiment results reveal that there exist vibration attenuation zones in acceleration frequency responses which can be improved by increasing the number of periods or tuning some structure parameters. The presence of soft fillers shifts the attenuation zone to lower frequencies and enhances the capability of vibration isolation to some extent. Dispersion relations and acceleration frequency responses are calculated by finite element method using COMSOL MULTIPHYSICS. The attenuation zones obtained by experiments fit well with that by simulations, and both are consistent with the band gap in dispersion relations. The numerical and experimental studies in the present paper show that this PC sandwich plate exhibits a good performance on vibration isolation in low frequency ranges, which will provide some useful references for relevant research and potential applications in vibration propagation manipulations.

Optimization of Vehicle Powertrain Mounting System and its Performance

2013 ◽  
Vol 441 ◽  
pp. 580-583
Author(s):  
Gong Yu Pan ◽  
Xin Yang ◽  
You Yan
Keyword(s):  
Vibration Isolation ◽  
Dynamics Model ◽  
Acceleration Response ◽  
Idle State ◽  
Decoupling Method ◽  
Before And After ◽  
Vibration Transmissibility ◽  
Six Degree Of Freedom ◽  
Vibration Isolation Performance ◽  
Isolation Performance

In order to solve the vibration problem of diesel engine powertrain assembly at its idle state, a six degree-of-freedom dynamics model of the powertrain mounting system is established and a optimization based on Adams/View is applied to simulation and analysis on the powertrain mounting system with energy decoupling method. The results show that the optimized repositioning mounts installation position can effectively improve decoupling rate in main vibration directions of mounting system. Based on this, the vibration transmissibility and acceleration response before and after optimization are simulated. The results show that the optimized engine mounting system makes a great improvement of vibration isolation performance.

The effect of side-restraint bearings on the performance of base-isolated buildings

2003 ◽  
Vol 217 (8) ◽  
pp. 849-859 ◽  
Author(s):  
J P Talbot ◽  
H E M Hunt
Keyword(s):  
Vibration Isolation ◽  
Base Isolation ◽  
Vertical Direction ◽  
Vertical Motion ◽  
Urban Road ◽  
Common Solution ◽  
Generic Models ◽  
Isolation Frequency ◽  
Flexible Foundation ◽  
Isolation Performance

Base-isolation of buildings is a common solution to the problem of ground-borne vibration from urban road and rail networks. Conventional designs incorporate vibration isolation bearings between a building and its foundation, aligned in the vertical direction so as to isolate the building from vertical motion of its foundation. In some cases, in order to accommodate horizontal loads, additional side-restraint bearings aligned in the horizontal direction are required. This paper describes a theoretical investigation into the effect of side-restraint bearings on the performance of base-isolated buildings. Three generic models, based on a modern concrete-framed building, are used to demonstrate that a building's flexibility, the nature of the vibration input and the presence of a flexible foundation are all important in determining isolation performance. It is also illustrated how the concept of isolation frequency, commonly used to indirectly specify the stiffness of base bearings, may not be generally extended to side-restraint bearings. The models indicate that, for maximum performance, the stiffness of any side-restraint bearings should be minimized.

Analysis and optimization of coupled vibration between substructures of a multi-axle vehicle

2018 ◽  
Vol 25 (5) ◽  
pp. 1031-1043 ◽  
Author(s):  
Jiewei Lin ◽  
Zefeng Lin ◽  
Liang Ma ◽  
Tianshu Xu ◽  
Daliang Chen ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Vibration Isolation ◽  
Ride Comfort ◽  
Coupling Effect ◽  
Attenuation Factor ◽  
Coupling Factor ◽  
Latin Hypercube Design ◽  
Trade Offs ◽  
Vibration Attenuation ◽  
Vibration Coupling

The vibration from transport vehicles may negatively affect the ride comfort in the cab and the product safety in the carriage. A 15 degrees of freedom vehicle model consisted of a cab, a carriage, a chassis, and mounts and suspensions between them are introduced to present the vibration behavior of a three-axle vehicle. Two indices, the coupling factor and the vibration attenuation factor, are employed to quantify the correlation between structures and the vibration isolation capability of subsystems. A sensitivity analysis is carried out with a 43-factor optimal Latin hypercube design, concerning the effect of mass properties, geometries, stiffness, and damping on the vibration coupling effect and the vibration attenuation of subsystems. Results show obvious trade-offs between the vibration coupling effect and the vibration attenuation among different subsystems. Based on the significant factor identified, multi-objective optimizations are conducted to improve the vibration performance of both the cab and the carriage and simultaneously reduce the correlations between structures using different algorithms. Comparison between different optimal results indicates that a compromise can be achieved between the ride comfort and the cargo safety based on a lightweight constraint.

Effectiveness of a Transfer Function Method for Evaluating Vibration Isolation Performance of Gloves When Used with Chipping Hammers

2002 ◽  
Vol 21 (3) ◽  
pp. 141-155 ◽  
Author(s):  
R.G. Dong ◽  
T.W. McDowell ◽  
D.E. Welcome ◽  
S. Rakheja ◽  
S. A. Caporali ◽  
...  
Keyword(s):  
Transfer Function ◽  
Function Method ◽  
Vibration Isolation ◽  
Prediction Method ◽  
Good Prediction ◽  
Mean Values ◽  
Transfer Function Method ◽  
Vibration Transmissibility ◽  
Vibration Isolation Performance ◽  
Isolation Performance

Anti-vibration gloves have been used as personal protective equipment to reduce the exposure intensity of hand-transmitted vibration. Although a method based upon the measured transfer function has been recently proposed to predict the tool-specific anti-vibration performance of these gloves, its validity for real tool applications has not been sufficiently evaluated. In this study, the effectiveness of the proposed prediction method was examined using two typical vibration-attenuation gloves when used in conjunction with two different pneumatic chipping hammers. Six adult male subjects were employed in the experiments involving measurement of gloves transmissibility while operating the selected tools. A comparison of the measured vibration transmissibility with the predicted values revealed that the transfer function method provides a reasonably good prediction of the vibration isolation performance of the gloves. The differences between the predicted and measured mean values of the weighted transmissibility were surprisingly small. It is concluded that the transfer function method can serve as an effective and convenient approach for estimating the effectiveness of anti-vibration gloves when used with pneumatic chipping hammers. A pneumatic chipping hammer is considered to represent a critical case for the evaluation of the method because they are typical percussive tools that generate impact vibration. It is thus anticipated that the transfer function method may also be widely employed to predict anti-vibration glove performance when used with many other vibrating tools.

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.

Vibration transmissibility suppression for hydraulic excavators in working conditions via multi-objective optimization

2021 ◽  
pp. 095745652110557
Author(s):  
Yong Chen ◽  
Mian Jiang ◽  
Daoyong Wang ◽  
Kuanfang He
Keyword(s):  
Working Conditions ◽  
Vibration Isolation ◽  
Optimization Process ◽  
Multi Objective Optimization ◽  
Multi Objective ◽  
Stiffness Coefficients ◽  
Hydraulic Excavators ◽  
Vibration Transmissibility ◽  
Vibration Isolation Performance ◽  
Isolation Performance

The mass variances of materials in buckets and the movements of excavation arms greatly impact powertrain vibration transmissibility in hydraulic excavators under working conditions. If the influence of mass variation among bucket contents and excavation arm motions on vibration transmissibility is not considered, then only limited improvements can be made to vibration isolation performance. In this paper, vibration transmissibility suppression for hydraulic excavators operating under working conditions were studied via multi-objective optimization for stiffness coefficients of suspension elements (SEs). First, the rigid-flexible coupling model of a hydraulic excavator with a flexible base was built using ADAMS software. In the model, the stiffness coefficients of the SEs were the targeted variables with constrained conditions, while the multi-objectives for optimization were the vibration transmissibility and energy decoupling rates of the powertrain. Vibration isolation transmissibility (VIT) of the mounting system was compared between situations with non-optimized and optimized stiffness coefficients. Finally, the amplitude changes of the resultant SE support forces were used to illustrate the effects of powertrain vibration transmissibility suppression. We found that the average value of VITs increases significantly during the optimization process for the stiffness coefficients of SEs, which indicates that the mounting system has better vibration isolation performance. The smaller amplitudes of the resultant support force illustrate the improvements to the performance of vibration transmissibility suppression of the powertrain via the optimization process.

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