scholarly journals Study on Dynamic Characteristics of Aerostatic Bearing with Elastic Equalizing Pressure Groove

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Xiao-long Zhao ◽  
Hao Dong ◽  
Zhou Fang ◽  
Deng-di Chen ◽  
Jun-an Zhang
Keyword(s):  
Dynamic Characteristics ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Coupling Model ◽  
Damping Coefficient ◽  
Aerostatic Bearing ◽  
Equivalent Damping ◽  
New Type ◽  
Equivalent Damping Coefficient ◽  
Control Equation

Microvibration has an important influence on the dynamic performance of aerostatic bearings. Dynamic stiffness and equivalent damping coefficient are the main indexes to evaluate the dynamic characteristics of the aerostatic bearing. In order to study the dynamic characteristics of a new type of aerostatic bearing with the elastic equalizing pressure groove (EEPG), the dynamic characteristics of the new type of bearing are studied by theoretical calculation and experiment. First, the dynamic gas-solid coupling control equation is established. Then, the steady term and the perturbation term are decomposed by the perturbation method. By solving the coupling model, the dynamic characteristics of the bearing are calculated and analyzed. The calculation results show that the perturbation frequency has a significant effect on the dynamic stiffness and equivalent damping coefficient of the aerostatic bearing with EEPG. The dynamic stiffness increases with the increase of frequency, and the equivalent damping coefficient decreases with the increase of frequency. The experimental results are basically the same with the theoretical results, which effectively verify the correctness of the theoretical analysis.

A new type of damper combining eddy current damping with rack and gear

2020 ◽  
pp. 107754632093711
Author(s):  
Yafeng Li ◽  
Shouying Li ◽  
Jianzhong Wang ◽  
Zhengqing Chen
Keyword(s):  
Eddy Current ◽  
Permanent Magnets ◽  
Air Gap ◽  
Damping Coefficient ◽  
Apparent Mass ◽  
Damping Force ◽  
Equivalent Damping ◽  
Eddy Current Damping ◽  
New Type ◽  
Equivalent Damping Coefficient

A new type of damper combining eddy current damping with rack and gear, which can simultaneously export damping and inertial forces, is proposed. Eddy current damping with rack and gear is supposed to be installed between the building superstructure and foundation to mitigate the seismic response of the building. First, the concept of eddy current damping with rack and gear is introduced in detail and its apparent mass and equivalent damping coefficient are both theoretically investigated. Second, a prototype of eddy current damping with rack and gear is manufactured, and a series of tests on the prototype are carried out to verify its structural parameters. The experimental and theoretical results of the apparent mass of the prototype agree well with each other. The experimental result of the equivalent damping coefficient of the prototype is slightly lower than the numerical results obtained from COMSOL Multiphysics and its maximum relative differences are 11.3% and 13.6% for α = 0° and 45°, respectively. Third, detailed parametric studies on the damping force, including the effects of the thickness of the conductor plate, air gap, and number and location of permanent magnets, are conducted. The results show that the damping force keeps a linear relationship with velocity if it is lower than 0.15 m/s, and with the increase of the velocity, a strong nonlinear relationship between the damping force and the velocity is observed. The available maximum damping force can be increased by decreasing the thickness of the conductor plate and the air gap, increasing the number of permanent magnets. There is an optimal location about the permanent magnets for the available maximum damping force. In addition, the hysteretic curves of the eddy current damping with rack and gear obtained from the test indicate that the ability of energy dissipation is considerable.

The Calculation of the Equivalent Linear Damping Coefficient of the Magnetorheological Damper

2013 ◽  
Vol 336-338 ◽  
pp. 475-479 ◽  
Author(s):  
Yao Hui Guo ◽  
En Wei Chen ◽  
Qun Wu ◽  
Yi Min Lu ◽  
Zeng Qiang Xia
Keyword(s):  
Mr Damper ◽  
Magnetorheological Damper ◽  
Damping Coefficient ◽  
Control Voltage ◽  
Characteristic Analysis ◽  
Equivalent Damping ◽  
Equivalent Linear ◽  
Linear Damping ◽  
Damper Control ◽  
Equivalent Damping Coefficient

MR damper (magnetorheological damper) has broad application prospects, and equivalent damping coefficient is very important of its dynamic characteristic analysis. Based on the modified Bouc_Wen model, the performance of MR damper was analyzed and the equivalent linear damping coefficient of MR damper was calculated. Based on simulation date of the modified Bouc_Wen model, the relationships between the equivalent linear damping coefficient of MR damper and the parameters of control voltage and MR dampers movement amplitude were established by the curve fitting regression analysis method. Verification results prove that the equivalent linear damping coefficient model has higher accuracy. For the vibration systems using strongly nonlinear MR damper, new model can effectively improve the efficiency of calculating the vibration analysis and the stability of the system in a certain frequency. At the same time, the model provides a theoretical basis for the application of MR damper control.

Dynamic Characteristics Analysis of Axle Box Spring by FEM

2013 ◽  
Vol 712-715 ◽  
pp. 1535-1540
Author(s):  
Li Liu ◽  
Wei Hua Zhang ◽  
Dong Li Song
Keyword(s):  
Dynamic Characteristics ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Excitation Frequency ◽  
Railway Vehicle ◽  
Helical Spring ◽  
Working Stress ◽  
Characteristics Analysis ◽  
In Series ◽  
Spring Method

Axle box spring of railway vehicle is the structure of helical spring in series with rubber pad to reduce working stress of helical spring and absorb high-frequency vibration. Rubber pad model was built. Static and dynamic characteristics were researched in axial and radial directions. The results show that the static stiffness of rubber pad decreases with the increase of radial displacement and increases distinctly with the increase of the amount of compression; The dynamic stiffness of rubber pad increases with the decrease of the excitation force in the case of the same excitation frequency and decreases with the decrease of the frequency in the case of the same excitation displacement. Axle box spring method was established and the amplitude-frequency curve of dynamic stiffness of the spring was presented. The results provide a theoretical basis to research the dynamic performance of railway vehicle.

Effect of Clamped Toolholders on Dynamic Characteristics of Spindle System of Machining Center

2012 ◽  
Vol 6 (2) ◽  
pp. 168-174 ◽  
Author(s):  
Haruhisa Sakamoto ◽  
◽  
Taiga Matsuda ◽  
Shinji Shimizu ◽  
Keyword(s):  
Dynamic Characteristic ◽  
Dynamic Characteristics ◽  
Dynamic Stiffness ◽  
Physical Parameters ◽  
Characteristic Parameters ◽  
Spindle System ◽  
Press Fit ◽  
Equivalent Damping Coefficient ◽  
Response Method ◽  
Tooling System

In this study, dynamic characteristics are determined based on the impulse response method, the correction of discretization errors and the identification of equivalent physical parameters, as found in the vibration model having one degree of freedom. In the experiments, the test tool is cylindrical bar shaped and made from solid tungsten carbide, and four toolholders with chucking mechanisms, including the shrinkfit type, collet type, hydraulic type, and press-fit type, are used. Since it had been previously confirmed that one of the tool preparation jigs had dynamic characteristics similar to those of an actual machine tool’s spindle, the dynamic characteristics of the jig could be measured the way the spindle system is measured in this study. From the experimental examinations, the following were clarified. (1) Chucking of the tooling system enhances the first mode vibration of the spindle system markedly. (2) The type of tool chuck used changes the dynamic characteristics of the spindle system. The trend in the dynamic stiffness corresponds well with that in the equivalent damping coefficient but is opposite to that in the equivalent stiffness. (3) The magnitude order of the dynamic characteristic parameters of the spindle system corresponds well with the inherent values of the dynamic characteristic parameters of the toolholders themselves; that is, the inherent dynamic characteristics of the tooling system can be used as the criteria to estimate the effect on the dynamic characteristics of the spindle system.

Analysis of dynamic characteristics of spiral groove liquid film seal under thermal–fluid–solid coupling

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Bo Yu ◽  
Muming Hao ◽  
Sun Xinhui ◽  
Zengli Wang ◽  
Liu Fuyu ◽  
...  
Keyword(s):  
Steady State ◽  
Liquid Film ◽  
Dynamic Characteristics ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Analysis Model ◽  
Spiral Groove ◽  
Content Type ◽  
Sealing Performance ◽  
Stiffness And Damping

Purpose The purpose of this paper is to investigate the dynamic characteristics of spiral groove liquid film seal under the effect of thermal–fluid–solid coupling. Design/methodology/approach The dynamic analysis model of spiral groove liquid film seal under the effect of thermal–fluid–solid coupling was established by perturbation method. The steady-state and perturbation Reynolds equations were solved, and the steady-state sealing performance and dynamic characteristic coefficients of the liquid film were obtained. Findings Compared with the liquid film without coupling method, a divergent seal gap is formed between the seal rings under the effect of thermal–fluid–solid coupling, the minimum liquid film thickness decreases, the dynamic stiffness and damping coefficients of the liquid film are increased and the thermoelastic deformation of the end-face improves the dynamic performance of the liquid film seal. Originality/value The dynamic characteristics of the spiral groove liquid film seal under the effect of thermal–fluid–solid coupling are studied, which provides a theoretical reference for optimizing the dynamic performance of the non-contacting liquid film seal.

Experimental Analysis of the Dynamic Characteristics of a Foil Thrust Bearing

2014 ◽  
Author(s):  
Franck Balducchi ◽  
Mihai Arghir ◽  
Romain Gauthier
Keyword(s):  
Dynamic Characteristics ◽  
Experimental Analysis ◽  
Dynamic Models ◽  
Thrust Bearing ◽  
Dynamic Stiffness ◽  
Excitation Frequency ◽  
Test Rig ◽  
Equivalent Damping ◽  
Start Up ◽  
Foil Thrust Bearing

The paper deals with the experimental analysis of the dynamic characteristics of a foil thrust bearing (FTB) designed following the specifications given by NASA in 2009. The start-up characteristics of the same foil bearing were investigated in a recently published paper. The test rig used for start-up measurements was adapted for dynamic measurements. The paper presents the test rig in detail as well as its identified dynamic models. Measurements of the dynamic characteristics of the bump foil structure were performed for static loads comprised between 30 N and 150 N while measurements for the FTB were performed at 35 krpm for 30 N, 60 N and 90 N. Excitation frequencies were comprised between 150 Hz and 750 Hz. Results showed that the dynamic stiffness of the FTB increase with excitation frequency while the equivalent damping decreases. Both stiffness and damping increase with the static load but are smaller at 35 krpm compared to 0 rpm.

Experimental Analysis of the Dynamic Characteristics of a Foil Thrust Bearing

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Franck Balducchi ◽  
Mihai Arghir ◽  
Romain Gauthier
Keyword(s):  
Dynamic Characteristics ◽  
Experimental Analysis ◽  
Gas Turbines ◽  
Thrust Bearing ◽  
Dynamic Stiffness ◽  
Excitation Frequency ◽  
Equivalent Damping ◽  
Start Up ◽  
And Performance ◽  
Foil Thrust Bearing

This paper deals with the experimental analysis of the dynamic characteristics of a foil thrust bearing (FTB) designed according to specifications given by NASA scientists in 2009 (Dykas et al., 2009, “Design, Fabrication, and Performance of Foil Gas Thrust Bearings for Microturbomachinery Applications,” ASME J. Eng. Gas Turbines Power, 131(1), p. 012301). The present work details the new configuration of the same test rig that was used to test start-up characteristics of the aforementioned bearing (Balducchi et al., 2013, “Experimental Analysis of the Start-Up Torque of a Mildly Loaded Foil Thrust Bearing,” ASME J. Tribol., 135(3), p. 031703). The rig has been reconfigured to test dynamic characteristics. The dynamic characteristics of the bump foil structure were measured for static loads comprised between 30 N and 150 N while measurements for the FTB were performed at 35 krpm for 30 N, 60 N, and 90 N. Excitation frequencies were comprised between 150 Hz and 750 Hz. Results showed that the dynamic stiffness of the FTB increase with excitation frequency while the equivalent damping decreases. Both stiffness and damping increase with the static load but are smaller at 35 krpm compared to 0 rpm.

Experimental study on dynamic performance of typical nonballasted track systems using a full-scale test rig

2016 ◽  
Vol 231 (4) ◽  
pp. 470-481 ◽  
Author(s):  
Mingze Wang ◽  
Chengbiao Cai ◽  
Shengyang Zhu ◽  
Wanming Zhai
Keyword(s):  
Experimental Study ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Full Scale ◽  
Damping Coefficient ◽  
Full Scale Test ◽  
Test Rig ◽  
Scale Test ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping

This paper presents an experimental study on dynamic performance of China Railway Track System (CRTS) series track systems using a full-scale test rig. The test rig has been constructed based on 55.17 m long full-scale nonballasted tracks composed of four typical CRTS track elements in high-speed railways. First, the dynamic characteristics of different nonballasted tracks are investigated by conducting wheel-drop tests, where a wheel-drop testing vehicle with a dropping wheelset is devised to provide the wheel-drop load. The vibration levels of different track systems are assessed by the root-mean-square acceleration per one-third octave band, and the vibration transmission characteristics of the CRTS series tracks are evaluated by transfer functions. Further, a mathematical track model is used to extract the dynamic stiffness and damping coefficient of the four types of nonballasted track systems based on the wheel–rail impact response. The vibration characteristics, the dynamic stiffness, and damping coefficient of different nonballasted track systems under various wheel-drop heights are compared and discussed in detail.

Dynamic Characteristics Research of Magneto-Rheological Fluid Engine Mount

2015 ◽  
Vol 752-753 ◽  
pp. 913-917
Author(s):  
Gong Yu Pan ◽  
Qian Qian Wang ◽  
Xin Yang
Keyword(s):  
Dynamic Characteristics ◽  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Simulation Software ◽  
New Type ◽  
Engine Mount ◽  
Magneto Rheological ◽  
Stiffness And Damping ◽  
Vibration Isolation Performance ◽  
Isolation Performance

In order to improve the vibration isolation performance of engine mount, a new type of magneto-rheological semi-active mount with multiple inertia tracks is designed based on the existing magneto-rheological semi-active mount . The mechanical model is established according to the mount. The expression of the dynamic stiffness and damping lag angle is deduced, then the dynamic characteristics is simulated in the simulation software. At the same time, verify this model correct by the experiments.

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