An Approach to Investigate Dynamic Parameters of Bearings Joint Surfaces Based on the SDOF System

2013 ◽  
Vol 470 ◽  
pp. 504-509
Author(s):  
Lian Bao Wang ◽  
Xiao Qiu Hu ◽  
Xiang Long Dong
Keyword(s):  
Dynamic Characteristics ◽  
Hot Spot ◽  
Dynamic Stiffness ◽  
Modal Testing ◽  
Ball Bearings ◽  
Dynamic Parameters ◽  
Cnc Machine ◽  
Sdof System ◽  
Joint Surfaces ◽  
Stiffness And Damping

As commonly supporting parts of the spindle and the feed systems on the high-end grade CNC machine tool, the dynamic characteristics of angular contact ball bearings had been a research hot spot in the current. Aiming at solving the problem that obtained dynamic stiffness and damping of angular contact ball bearings, an approach to investigate dynamic parameters of bearings joint surfaces was proposed based on the single degree of freedom (SDOF) system, and several groups of modal testing were carried out. The dynamic characteristics of bearings joint surfaces were viewed as several viscoelastic units of spring and damper. Then, models of bearings dynamic parameters in the axial and radial directions were established, and several groups of modal simulation were carried out. The comparison of experiment and simulation results showed that the proposed approach could accurately identify dynamic stiffness and damping of bearings under different load conditions, and the errors were controlled within 7.6%.

Dynamic Parameters Equivalent Modeling of Bearings Joint Surfaces Based on the Virtual Material

2013 ◽  
Vol 433-435 ◽  
pp. 35-39
Author(s):  
Lian Bao Wang ◽  
Xiao Qiu Hu ◽  
Wei Fu Chen
Keyword(s):  
Dynamic Characteristic ◽  
Hot Spot ◽  
Dynamic Stiffness ◽  
Equivalent Model ◽  
Ball Bearings ◽  
Dynamic Parameters ◽  
Cnc Machine ◽  
Joint Surfaces ◽  
Relative Errors ◽  
Stiffness And Damping

As commonly supporting parts of the spindle and the feed systems on the high-end grade CNC machine tool, dynamic characteristic of angular contact ball bearings had been a research hot spot in the current. Aiming at solving the problem that obtained the dynamic stiffness and damping of angular contact ball bearings, the factors of joint surfaces dynamic characteristic were equivalently viewed as a kind of virtual material in the paper, and an equivalent model of dynamic parameters for bearings joint surfaces was proposed based on the virtual material; an experimental device was developed to test the bearings dynamic parameters. The comparison of experimental results and simulation results showed that modal parameters of bearings could be accurately analyzed by the proposed modeling approach, and the relative errors of corresponding vibration frequencies in the radial and the axial directions could be controlled within 7%.

Experimental Investigation of Dynamic Normal Characteristics of Machined Joint Surfaces

2000 ◽  
Vol 122 (4) ◽  
pp. 393-398 ◽  
Author(s):  
W. P. Fu ◽  
Y. M. Huang ◽  
X. L. Zhang ◽  
Q. Guo
Keyword(s):  
Experimental Investigation ◽  
Dynamic Characteristics ◽  
Static Pressure ◽  
Dynamic Stiffness ◽  
Relative Displacement ◽  
Test Range ◽  
Joint Surfaces ◽  
Exciting Frequency ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping

This paper presents an experimental investigation on the normal dynamic characteristics of several machined joint surfaces, i.e., the varying principle of the normal dynamic stiffness and damping with exciting frequency, relative displacement and static pre-load under different joint conditions, including joint materials, mediums, machining methods and surface roughness, etc.. The joint parameters are extracted from experimental data by establishing the theoretical model of the joint surfaces, and the mechanism is analyzed qualitatively. The studied results show that, in the test range of this paper, the stiffness and damping coefficient of the joint surfaces increase with the static pre-load; the stiffness for a dry joint is independent of the exciting frequency, while the damping coefficients for both a dry and an oiled joint decrease with the exciting frequency; little relative displacement has no marked effect on the dynamic characteristics. The amount of influence of exciting frequency and static pressure is related to the joint conditions. [S0739-3717(00)00804-7]

Design and structural performance measurements of a novel multi-cantilever foil bearing

2014 ◽  
Vol 229 (10) ◽  
pp. 1830-1838 ◽  
Author(s):  
Kai Feng ◽  
Xueyuan Zhao ◽  
Zhiyang Guo
Keyword(s):  
Dynamic Characteristics ◽  
Dynamic Load ◽  
Dynamic Stiffness ◽  
Excitation Frequency ◽  
Viscous Damping ◽  
Equivalent Viscous Damping ◽  
Foil Bearing ◽  
Load Tests ◽  
Stiffness And Damping ◽  
Motion Amplitude

With increasing need for high-speed, high-temperature, and oil-free turbomachinery, gas foil bearings (GFBs) have been considered to be the best substitutes for traditional oil-lubricated bearings. A multi-cantilever foil bearing (MCFB), a novel GFB with multi-cantilever foil strips serving as the compliant underlying structure, was designed, fabricated, and tested. A series of static and dynamic load tests were conducted to measure the structural stiffness and equivalent viscous damping of the prototype MCFB. Experiments of static load versus deflection showed that the proposed bearing has a large mechanical energy dissipation capability and a pronounced nonlinear static stiffness that can prevents overly large motion amplitude of journal. Dynamic load tests evaluated the influence of motion amplitude, loading orientation and misalignment on the dynamic stiffness and equivalent viscous damping with respect to excitation frequency. The test results demonstrated that the dynamic stiffness and damping are strongly dependent on the excitation frequency. Three motion amplitudes were applied to the bearing housing to investigate the effects of motion amplitude on the dynamic characteristics. It is noted that the bearing dynamic stiffness and damping decreases with incrementally increasing motion amplitudes. A high level of misalignment can lead to larger static and dynamic bearing stiffness as well as to larger equivalent viscous damping. With dynamic loads applied to two orientations in the bearing midplane separately, the dynamic stiffness increases rapidly and the equivalent viscous damping declines slightly. These results indicate that the loading orientation is a non-negligible factor on the dynamic characteristics of MCFBs.

Dynamic Characteristics of Spiral-Grooved Opposed-Hemisphere Gas Bearings

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Guangwei Yang ◽  
Jianjun Du ◽  
Weiping Ge ◽  
Tun Liu ◽  
Xiaowei Yang
Keyword(s):  
Dynamic Characteristics ◽  
Degrees Of Freedom ◽  
Dynamic Stiffness ◽  
Translational Motion ◽  
Coupling Coefficients ◽  
Dynamic Coefficients ◽  
Large Eccentricity ◽  
The Stability ◽  
Stiffness And Damping ◽  
Gas Bearing

The traditional eight-coefficient bearing model only considers the translational motion of the bearings and neglects the tilting motion and coupling effects between them. In this paper, the dynamic characteristics of the spiral-grooved opposed-hemisphere gas bearing considering five degrees-of-freedom are studied, and 50 dynamic coefficients including the translational, tilting, and coupling components are completely calculated. The Reynolds equations and their perturbed equations are solved by the finite element method to obtain the dynamic stiffness and damping coefficients. The effects of the tilting motion on the dynamic coefficients and response are analyzed, respectively. The results show that the coupling coefficients between the translational and tilting motions, which have been neglected in most previous studies, are significant at large eccentricity ratio. But these coupling coefficients have little effect on the dynamic response. On the other hand, the influences of the tilting motion on the synchronous response and natural frequency are remarkable and will decrease the stability of the rotor bearing system.

Stiffness and Damping Characteristics of a Wide Parabolic Film Slider Bearing Operating with Ferrofluids

2014 ◽  
Vol 1052 ◽  
pp. 132-136
Author(s):  
Jaw Ren Lin
Keyword(s):  
Magnetic Fields ◽  
Dynamic Characteristics ◽  
Dynamic Stiffness ◽  
Slider Bearing ◽  
Inclined Plane ◽  
Damping Characteristics ◽  
Plane Film ◽  
Stiffness And Damping

This paper investigates the dynamic characteristics of parabolic film slider bearing operating with ferrofluids. Comparing with the slider bearing of an inclined plane film, the parabolic film slider bearing operating with ferrofluids in the presence of external magnetic fields provide higher better dynamic stiffness and damping performances.

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.

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.

scholarly journals Research on Static and Dynamic Characteristics of Shear Spring of the Vibrating Flip-Flow Screen

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1644
Author(s):  
Guofeng Zhao ◽  
Xinwen Wang ◽  
Chi Yu ◽  
Shucheng Liu ◽  
Jun Zhou ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
High Efficiency ◽  
Dynamic Stiffness ◽  
Test System ◽  
Normal Operation ◽  
Static And Dynamic Characteristics ◽  
Damping Coefficients ◽  
Operation Conditions ◽  
Shear Spring ◽  
Stiffness And Damping

The vibrating flip-flow screen (VFFS) is a high-efficiency device currently used for deep screening of moist fine-grained materials. During VFFS operation, the normal operation of the screen is affected by fatigue damage to the shear springs arranged symmetrically on both sides of the screen, leading to equipment failures and disruption production. In this paper, the shear spring’s static and dynamic characteristics in different operation conditions were studied using the INSTRON 8801 fatigue test system and Dynacell dynamic sensors. Using an experimental test of shear spring stiffness and damping coefficients, the effects of some factors, i.e., temperature, hardness, amplitude and frequency, were studied. The results show that the temperature of the shear spring on the left side of the flip-flow screen was higher than that of the right side (driving side). With an increase in temperature, the stiffness of the shear spring decreased. With the increase in amplitude, the dynamic stiffness decreased and the damping coefficients did not change; with the increase in frequency, the dynamic stiffness increased and the damping coefficient decreased. At the same amplitude, with the increase in hardness of the shear spring, the dynamic stiffness increased. Finally, the stiffness and damping coefficients of the shear spring before and after tearing were obviously reduced. These research results reveal the relationship of the characteristics of a shear spring with operational conditions, and could provide a theoretical reference for the design of the VFFS and the selection of the shear spring.

Dynamic Characteristics of Hydrostatic Thrust Air Bearing With Actively Controlled Restrictor

1988 ◽  
Vol 110 (1) ◽  
pp. 156-161 ◽  
Author(s):  
Yuichi Sato ◽  
K. Maruta ◽  
M. Harada
Keyword(s):  
Dynamic Characteristics ◽  
Dynamic Stiffness ◽  
Phase Lag ◽  
Air Bearing ◽  
Plate Vibrations ◽  
Damping Coefficients ◽  
Stiffness And Damping ◽  
Air Film ◽  
Theoretical Results ◽  
Good Agreement

The dynamic characteristics of a hydrostatic thrust air bearing with an actively controlled orifice restrictor are investigated theoretically and experimentally. Theoretical results show that the dynamic stiffness and damping coefficients can be increased simultaneously when the restrictor area is controlled with appropriate phase-lag to the change of air film thickness, that is, plate vibrations. Consequently stability of the bearing can be improved. Experimental results show fairly good agreement with theoretical ones.

Experimental Study of Dynamic Characteristics and Model Parameter Identification of Tensioner

2014 ◽  
Vol 988 ◽  
pp. 332-337
Author(s):  
Hong Yun Wang ◽  
Xiang Kun Zeng ◽  
Ji Yong Zhao
Keyword(s):  
Parameter Identification ◽  
Nonlinear Model ◽  
Dynamic Characteristics ◽  
Dynamic Stiffness ◽  
Excitation Frequency ◽  
Identification Method ◽  
Serpentine Belt ◽  
Drive Systems ◽  
Set Up ◽  
Stiffness And Damping

Tensioners play a predominant role in the dynamic behavior of serpentine belt drive systems. The experimental set-up was carried out to study the dynamic characteristics of tensioner. Experimental results illustrate that tensioner shows hysteresis nonlinear dynamic characteristics, and dynamic stiffness and damping of slip motion of up stroke of tensioner are related to excitation frequency and amplitude. The first differential nonlinear model of tensioner was determined, and the parameter identification method of the model was introduced. The accurate of the nonlinear model and effectiveness of the parameter identification method was validated.

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