scholarly journals Modeling and Dynamic Properties of a Four-Parameter Zener Model Vibration Isolator

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Wen-ku Shi ◽  
Chen Qian ◽  
Zhi-yong Chen ◽  
Yang Cao ◽  
Heng-hai Zhang
Keyword(s):  
High Performance ◽  
Dynamic Properties ◽  
Structural Parameters ◽  
Dynamic Stiffness ◽  
Installation Space ◽  
Structural Parameter ◽  
Channel Diameter ◽  
Zener Model ◽  
Isolation System ◽  
Stiffness And Damping

To install high-performance isolators in a limited installation space, a novel passive isolator based on the four-parameter Zener model is proposed. The proposed isolator consists of three major parts, namely, connecting structure, sealing construction, and upper and lower cavities, all of which are enclosed by four segments of metal bellows with the same diameter. The equivalent stiffness and damping model of the isolator are derived from the dynamic stiffness of the isolation system. Experiments are conducted, and the experiment error is analyzed. Test results verify the validity of the model. Theoretical analysis and numerical simulation reveal that the stiffness and damping of the isolator have multiple properties with different exciting amplitudes and structural parameters. In consideration of the design of the structural parameter, the effects of exciting amplitude, damp channel diameter, equivalent cylinder diameter of cavities, sum of the stiffness of the bellows at the end of the isolator, and length of damp channel on the dynamic properties of the isolator are discussed comprehensively. A design method based on the parameter sensitivity of the isolator’s design parameter is proposed. Thus, the novel isolator can be practically applied to engineering and provide a significant contribution in the field.

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 Modeling and Dynamics of a MDOF Isolation System

2017 ◽  
Author(s):  
Youshuo Song ◽  
Xiuting Sun
Keyword(s):  
Vibration Isolation ◽  
Vibration Suppression ◽  
Structural Parameters ◽  
Structural Parameter ◽  
Isolation System ◽  
Passive Components ◽  
Vibration Isolation System ◽  
Joint Friction ◽  
Engineering Practices ◽  
Stiffness And Damping

This study analyzes the modeling and dynamics of a novel passive in Multi-Degree-of-Freedom (MDOF) vibration isolation platform which can achieve significant isolation effect. Symmetrical Scissor-Like structures (SLSs) are utilized in the proposed MDOF isolation platform as the supporting and isolation elastic components. Based on the mathematical modeling and theoretical analysis of the MDOF vibration isolation system with SLSs, the effect of structural parameter and joint friction on stiffness and damping properties is investigated. It is shown that due to geometric relations within the SLSs, the natural frequencies can be reduced via adjusting structural parameters of the SLS for different direction vibration isolation. Theoretical and experimental results show that the SLS isolation platform can achieve much better loading capacity and vibration isolation performance simultaneously by only using linear passive components because of the MDOF adjustable stiffness property. Therefore, with low costing and energy consumption, the proposed novel isolation platform can provide the improvement of vibration suppression in various engineering practices.

Research on Modeling and Optimization of a Dual Chamber Air Spring Vibration Isolation System

2013 ◽  
Vol 702 ◽  
pp. 310-317 ◽  
Author(s):  
Cheng Zhang ◽  
Jian Fu Zhang ◽  
Ping Fa Feng ◽  
Ding Wen Yu ◽  
Zhi Jun Wu
Keyword(s):  
Vibration Isolation ◽  
Structural Parameters ◽  
Dynamic Stiffness ◽  
Theoretical Models ◽  
Air Spring ◽  
Dual Chamber ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Spring System ◽  
Stiffness And Damping

To improve the vibration isolation performanceof an air spring system,the characteristics of the dynamic stiffness and damping of adual chamber air springwere first analyzed. A theoretical model ofa four dual chamber air springs system wasthen constructed,and through experimental verification,the theoretical and experimental curves showedthe same change trend.Based on the theoretical models, anobjective function used to optimize the structural parameters of an air springwas constructed. It was demonstrated that the vibration isolation performance of the air spring system was improved with the optimized parameters.

scholarly journals Dynamic Stiffness and Damping Characteristics of a Shaft Damping Ring: A Combined Hyperelastic and Viscoelastic Constitutive Model

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Miaomiao Li ◽  
Jian Chen ◽  
Rupeng Zhu ◽  
Cheng Duan ◽  
Shuai Wang ◽  
...  
Keyword(s):  
Constitutive Model ◽  
Structural Parameters ◽  
Dynamic Stiffness ◽  
Constitutive Models ◽  
Operating Conditions ◽  
Uniaxial Tensile ◽  
Bending Vibrations ◽  
Damping Characteristics ◽  
Shaft System ◽  
Stiffness And Damping

At higher velocities, the helicopter tail transmission system encounters notable difficulties due to excessive bending vibrations. The shaft damping ring installed on the shaft system was shown to effectively suppress the shaft system vibrations. In this paper, the dynamic stiffness and damping characteristics of polyurethane shaft damping rings were studied using hyperelastic and viscoelastic constitutive models. The constitutive model and the damping ring material parameters were determined using uniaxial tensile and double-shear frequency scanning tests. Based on the test results, the dynamic damping ring characteristics were simulated and verified by dynamic stiffness tests; the influence of structural parameters and operating conditions on the dynamic stiffness and damping characteristics of the damping ring were obtained. The results provide a theoretical basis for the design of shaft systems with reduced sensitivity to vibrations.

Study on the Newly Developed 3-Dimensional Base Isolation System Using a Velocity Reduction Mechanism

2004 ◽  
Author(s):  
Tomohiro Ito ◽  
Katsuhisa Fujita ◽  
Takeshi Ohkubo
Keyword(s):  
Natural Frequency ◽  
High Performance ◽  
Base Isolation ◽  
Structural Parameters ◽  
Active Components ◽  
Isolation System ◽  
Velocity Reduction ◽  
Base Isolation System ◽  
Rocking Motion ◽  
Isolation Systems

Due to the Hyogo-ken Nambu Earthquake in 1995 and the huge earthquakes which are considered to occur in near future, the raise in the seismic design criteria in the horizontal and vertical excitations has been investigated. According to these trends, many base isolation structures have been developed and constructed. However, the most of these structures are limited to the horizontal base isolation. Therefore, the development of the effective 3-dimentional base isolation system becomes more and more important. The conventional 3-dimentional base isolation systems proposed up to now are insufficient in reducing the vertical natural frequency, otherwise are very complex due to facilitation of the active components. In this study, the dynamic characteristics of a high performance 3-dimentional base isolation system newly developed by the authors are reported. This system employs a velocity reduction system using a gear mechanics which can reduce the vertical natural frequency less than 1Hz while that of the conventional system is around 3Hz. And also this employs friction dampers to suppress the large displacement. Further, this system is facilitated with a rocking-suppression system which can effectively suppress the rocking motion inevitable for 3-dimentional base isolation. The response acceleration, displacement and rocking motion are evaluated by numerical simulations in varying the friction force, the predominant frequency of seismic input waves, the eccentricity of the upper structural mass, etc.. As the results, it is shown that the base isolation system developed here has very effective base isolation characteristics and the rocking suppression effects. And the optimization of the structural parameters is also discussed.

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.

Dynamic Identification of 280mm Diameter Tilting Pad Journal Bearings: Test Results and Measurement Uncertainties Assessment of Different Designs

2020 ◽  
Author(s):  
Riccardo Ferraro ◽  
Alice Innocenti ◽  
Mirko Libraschi ◽  
Michele Barsanti ◽  
Enrico Ciulli ◽  
...  
Keyword(s):  
High Performance ◽  
Dynamic Properties ◽  
Journal Bearings ◽  
Turbulent Regime ◽  
Dynamic Identification ◽  
Damping Characteristics ◽  
Flexible Rotors ◽  
Tilting Pad ◽  
Stiffness And Damping ◽  
Tilting Pad Journal Bearings

Abstract Tilting pad journal bearings (TPJBs) are crucial elements in turbomachinery applications providing stiffness and damping characteristics that determine rotor system dynamic behavior. Hence, a correct design and an accurate dynamic properties prediction is fundamental for the successful industrial operation of rotating machinery. Current design trends in turbomachinery aiming at higher efficiency and power through weight optimization and higher operating speeds determine the development of large flexible rotors that are particularly important from the rotordynamic standpoint. The dynamic feasibility of this type of machine relies on bearing stiffness and damping characteristics that must be predicted with a certain level of confidence in order to increase the accuracy of the expected rotordynamic behaviour and avoid unpredicted vibration issues when rotors are operated. Furthermore, large centrifugal compressors commonly used in Liquified Natural Gas (LNG) applications make the bearings operate at very high peripheral speed where the transition from laminar to turbulent regime occurs, increasing the necessity of predictions accuracy. In this paper a test campaign on different large TPJB solutions operating in turbulent lubrication regime has been performed on a dedicated test rig designed for investigations on large size high-performance oil bearings. In the present work both static performance and dynamic identification of the tested TPJB solutions are presented and compared to numerical model predictions. The results of an uncertainty quantification, performed to validate the experimental results, are also shown.

scholarly journals Dynamic Properties of Pretreated Rubberized Concrete under Incremental Loading

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2183
Author(s):  
Aijiu Chen ◽  
Xiaoyan Han ◽  
Zhihao Wang ◽  
Tengteng Guo
Keyword(s):  
Stress Level ◽  
Dynamic Properties ◽  
Dynamic Stiffness ◽  
Damping Ratio ◽  
Rubberized Concrete ◽  
Rubber Content ◽  
Rubber Particles ◽  
Energy Dissipation Capacity ◽  
Stiffness And Damping ◽  
Incremental Loading

Recycling scrap tyres as alternative aggregates of concrete is an innovative option. To clarify the dynamic properties of the pretreated rubberized concrete with some cumulative damage, the natural frequency, flexural dynamic stiffness, and damping ratio of the specimens under incremental stress level were investigated in this paper. The results indicated that the pretreatment of rubber particles improved the strength, ductility, and crack resistance of the rubberized concrete. The reduction of the flexural dynamic stiffness was clarified with the increase of concrete stress level. The addition of the pretreated rubber particles enhanced the concrete energy dissipation capacity during the destruction, and the specimen dissipated more energy with the increase of rubber content before its failure.

Structural Parameter Optimization and Simulation Analysis of the Chemical Sensor Support for Food Safety Detection

2010 ◽  
Vol 439-440 ◽  
pp. 875-879
Author(s):  
Fu Zhao ◽  
Ping Wang ◽  
Yan Jue Gong ◽  
Li Zhang ◽  
Chun Ling Meng
Keyword(s):  
Food Safety ◽  
Chemical Sensor ◽  
Simulation Analysis ◽  
Structural Parameters ◽  
Dynamic Stiffness ◽  
Optimization Method ◽  
Structural Parameter ◽  
Element Analysis ◽  
Food Detection ◽  
Optimization And Simulation

This paper focuses on the structural optimization of chemical sensor support for food safety detection. The mechanical characteristic of chemical sensor support is influenced greatly by its structural parameters. Aiming at improving dynamic stiffness of the support, the modal analysis is implemented with the dynamic theory and the finite element analysis. And a group of rational structure parameters are determined through the optimum calculation. The validity simulation of the optimization is verified by the analyses of the random vibration and harmonic response. The results demonstrate that the performance of the support of the chemical sensor applied for the food detection is enhanced greatly by the presented optimization method here.

scholarly journals Testing and Modelling of Elastomeric Element for an Embedded Rail System

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6968
Author(s):  
Qianqian Li ◽  
Roberto Corradi ◽  
Egidio Di Gialleonardo ◽  
Stefano Bionda ◽  
Andrea Collina
Keyword(s):  
Dynamic Properties ◽  
Reaction Force ◽  
Time History ◽  
Wide Frequency Range ◽  
Equivalent Stiffness ◽  
Zener Model ◽  
Elastomeric Material ◽  
Rail System ◽  
Non Linear ◽  
Stiffness And Damping

Modelling of elastomeric elements of railway components, able to represent stiffness and damping characteristics in a wide frequency range, is fundamental for simulating the train–track dynamic interaction, covering issues such as rail deflection as well as transmitted forces and higher frequency phenomena such as short pitch corrugation. In this paper, a modified non-linear Zener model is adopted to represent the dependences of stiffness and damping of the rail fastening, made of elastomeric material, of a reference Embedded Rail System (ERS) on the static preload and frequency of its deformation. In order to obtain a reliable model, a proper laboratory test set-up is built, considering sensitivity and frequency response issues. The equivalent stiffness and damping of the elastomeric element are experimentally characterised with force-controlled mono-harmonic tests at different frequencies and under various static preloads. The parameters of the non-linear Zener model are identified by the experimental equivalent stiffness and damping. The identified model correctly reproduces the frequency- and preload-dependent dynamic properties of the elastomeric material. The model is verified to be able to predict the dynamic behaviour of the elastomeric element through the comparison between the numerically simulated and the experimentally measured reaction force to a given deformation time history. Time domain simulations with the model of the reference ERS demonstrate that the modelled frequency- and preload-dependent stiffness and damping of the elastomeric material make a clear difference in the transient and steady-state response of the system when distant frequency contributions are involved.

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