Analysis of EHL Line Contact in Rapid Braking Motion

2013 ◽  
Vol 318 ◽  
pp. 220-224
Author(s):  
Li Jun Du ◽  
Yao Yao Hong ◽  
She Miao Qi
Keyword(s):  
Elastohydrodynamic Lubrication ◽  
Constant Load ◽  
Lubricating Oil ◽  
Line Contact ◽  
Transient Effects ◽  
Film Pressure ◽  
Oil Film ◽  
Braking Process ◽  
Almost All ◽  
Oil Film Pressure

As is well known, almost all the machines need to start and brake. In this process, the lubrication state of their parts changes instantaneously. In this paper, an isothermal study for the line contact elastohydrodynamic lubrication (EHL), which is in rapid braking process and under a constant load, is carried out by using a simplified multigrid method. Numerical results indicate that the oil film thickness decreases and the oil film pressure increases with the decrease of the speed during the process of rapid braking. The oil film shrinks quickly and the oil entrapment occurs when the speed reduces to a certain range. Simultaneously, the distribution of oil film pressure tends to the central lubrication area. The size of the oil entrapment area and the changes of the oil film pressure are closely related to the braking time and the initial speed, which reflects the transient effects of the lubricating oil film.

Influence of Surface Waviness on the Thermal Elastohydrodynamic Lubrication of an Eccentric-Tappet Pair

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
J. Wang ◽  
C. H. Venner ◽  
A. A. Lubrecht
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Surface Waviness ◽  
Film Pressure ◽  
Oil Film ◽  
Working Cycle ◽  
Temperature Oscillations ◽  
Minimum Film Thickness ◽  
Traction Coefficient ◽  
Oil Film Pressure

The effect of single-sided and double-sided harmonic surface waviness on the film thickness, pressure, and temperature oscillations in an elastohydrodynamically lubricated eccentric-tappet pair has been investigated in relation to the eccentricity and the waviness wavelength. The results show that, during one working cycle, the waviness causes significant fluctuations of the oil film, pressure, and temperature, as well as a reduction in minimum film thickness. Smaller wavelength causes more dramatic variations in oil film. The fluctuations of the pressure, film thickness, temperature, and traction coefficient caused by double-sided waviness are nearly the same compared with the single-sided waviness, but the variations are less intense.

The Elastohydrodynamic Lubrication Analysis of Composite Material Gear

2013 ◽  
Vol 706-708 ◽  
pp. 1622-1626
Author(s):  
Xiao Xin Fu ◽  
You Qiang Wang
Keyword(s):  
Numerical Simulation ◽  
Composite Material ◽  
Simulation Analysis ◽  
Elastohydrodynamic Lubrication ◽  
Gear Pair ◽  
Oil Lubrication ◽  
Film Pressure ◽  
Oil Film ◽  
Oil Film Pressure

The composite material gear was manufactured with modified PEEK materia1.The transient EHL solution of composite material gear was obtained by numerical simulation analysis in oil lubrication conditions.The simulation result of the composite material gear was compared with that of the steel-steel gear. The results show that the meshing oil film between composite material gear pair is thicker than that between steel-steel gear and the maximum oil film pressure in the meshing point between composite material gear is lower than that between steel-steel gear in the same conditions.

Research and Development of Overloading Velocity Jump Line Contact Elastohydrodynamic Lubrication Testbed

2015 ◽  
Vol 713-715 ◽  
pp. 182-186
Author(s):  
Nai Ming Miao
Keyword(s):  
Working Conditions ◽  
Friction Pair ◽  
Elastohydrodynamic Lubrication ◽  
Lubricating Oil ◽  
Glass Block ◽  
Contact Friction ◽  
Line Contact ◽  
Oil Film ◽  
Experimental Apparatus ◽  
Velocity Jump

To research the lubricating property of line contact elastohydrodynamic lubrication under the working conditions of overloading velocity jump, based on the optic elastohydrodynamic experimental apparatus developed by the research group, an measuring equipment applicable to the oil film thickness and shape under the condition of overloading velocity jump is designed and developed. This testbed is mainly composed of glass block reciprocating motion system, ball or roller rotary rolling system, loading system, speed regulating system, light source system and image acquisition system. The motion part replaces the slider-crank mechanism with kad-screw mechanism and is driven by stepper motor, so as to realize the different working conditions of velocity jump. The developed platform was adopted to carry out the velocity jump line contact elastohydrodynamic lubrication test by the driving of the stepping motor, investigating the influence of line contact friction pair on the lubricating oil film at the moment of acceleration under the overloading working condition.

A Comparative Study of the Methods for Calculation of Journal Bearing Elastohydrodynamic Lubrication

2012 ◽  
Vol 594-597 ◽  
pp. 2727-2730
Author(s):  
Jun Yan Zhang ◽  
Shu Kui Han ◽  
Su Fen Zhang ◽  
You Wei Zhang
Keyword(s):  
Matrix Method ◽  
Journal Bearing ◽  
Elastohydrodynamic Lubrication ◽  
Eccentricity Ratio ◽  
High Eccentricity ◽  
Film Pressure ◽  
Oil Film ◽  
Flexibility Matrix ◽  
Steady Load ◽  
Oil Film Pressure

Based on the fast fourier transform（FFT） and flexibility matrix method, the study is presented for journal bearing elastohydrodynamic lubrication. The effects of FFT and flexibility matrix method on the distribution of oil film pressure and elastic deformation in the steady load are investigated. The results are shown that the difficulty of the EHL for journal bearings in the case of high eccentricity ratios or heave loads can be effectively solved by the FFT method. When the eccentricity ratio is smaller, the magnitude and distribution of the oil film pressure are basic agreement by FFT method and flexibility matrix method. When the eccentricity ratio enhances, the maximum oil film pressure obtained by FFT method is bigger on both ends of the journal bearing and on its intermediate is smaller.

Numerical Model of Journal Bearing Lubrication Considering a Bending Stiffness Effect

2013 ◽  
Vol 284-287 ◽  
pp. 854-860
Author(s):  
Juh Wan Choi ◽  
Seong Su Kim ◽  
Sung Soo Rhim ◽  
Jin Hwan Choi
Keyword(s):  
Numerical Model ◽  
Film Thickness ◽  
Journal Bearing ◽  
Elastohydrodynamic Lubrication ◽  
Bending Stiffness ◽  
Thickness Variation ◽  
Lubrication System ◽  
Film Pressure ◽  
Oil Film ◽  
Oil Film Pressure

An analysis for operating characteristics of journal bearing lubrication system is performed based on the numerical model. Dynamic bearing lubrication characteristics such as oil film pressure and thickness distribution can be analyzed through a numerical model with an integration of elastohydrodynamics and multi-flexible-body dynamics (MFBD). In particular, the oil film thickness variation by elastic deformation is considered in the elastohydrodynamic analysis by applying the bending stiffness effect of journal. And the oil film thickness variation by the bending stiffness effect is applied to the fluid governing equations to calculate the oil film pressure in the elastohydrodynamic lubrication region. A series of process proposed in this study is available for the analysis of realistic elastohydrodynamic lubrication phenomenon. Also, a numerical example for the journal bearing lubrication system is demonstrated and compared with the experimental results. The numerical results considering the bending stiffness effect show a good agreement with the experimental results.

Research on Load-Carrying Performances of Magnetic-Fluid Lubrication for Mill Oil-Film Bearing

2013 ◽  
Vol 712-715 ◽  
pp. 356-359
Author(s):  
Jian Mei Wang ◽  
Qing Xue Huang ◽  
Jian Zhao Sun ◽  
Xun Jie Huang ◽  
Jian Feng Kang
Keyword(s):  
Magnetic Field ◽  
Field Intensity ◽  
Magnetic Fluid ◽  
Magnetic Field Intensity ◽  
Lubricating Oil ◽  
Film Pressure ◽  
Oil Film ◽  
Lubricating Film ◽  
Load Carrying ◽  
Oil Film Pressure

The FEM model of lubricating oil film was built with mill oil-film bearing as the research target, the analysis system of magnetic-fluid lubricating oil film for oil-film bearing was developed. APDL and CEL languages were applied to compile the inner analytical programs, and the combination of VB, ANSYS Mechanical with ANSYS CFX was perfectly realized. Through the numerical simulation of magnetic-fluid lubricating film, the load-carrying performances of oil-film bearing with magnetic-fluid lubrication were analyzed, and the relationship among magnetic field intensity with oil-film pressure and temperature was quantitatively calculated. The numerical results have shown that the magnetic-fluid lubrication has obvious influences on oil-film pressure when magnetic field was applied on oil-film bearing, the lubricating viscosity increases with the magnetic-fluid intensity, and the oil-film pressure and temperature also increase with magnetic-field intensity. However, the increasing increment of oil-film temperature is far lower than that of oil-film pressure. The above conclusions prove that magnetic fluid with proper magnetic field can effectively improve the load-carrying capacity of lubricating oil film and enhances the stability of oil-film pressure. Moreover, the adjustable intelligent oil-film pressure with magnetic field is deduced to be feasible.

Simulation studies on static thermal behaviour of true elliptical and orthogonally displaced non-circular journal bearing

2016 ◽  
Vol 68 (3) ◽  
pp. 349-360 ◽  
Author(s):  
Amit Singla ◽  
Amit Chauhan
Keyword(s):  
Journal Bearing ◽  
Load Capacity ◽  
Current Trend ◽  
Operating Conditions ◽  
Performance Characteristics ◽  
Film Pressure ◽  
Content Type ◽  
Oil Film ◽  
Ellipticity Ratio ◽  
Oil Film Pressure

Purpose The current trend of modern industry is to use machineries which rotate at high speed along with the capability of carrying heavy rotor loads. This paper aims at static thermal analysis of two different profiles of non-circular journal bearings – a true elliptical bearing and orthogonal bearing. Design/methodology/approach The Reynolds equation has been solved through finite difference method to compute the oil film pressure. Parabolic temperature profile approximation technique has been used to solve the energy equation and thus used for computation of various bearing performance characteristics such as thermo-hydrodynamic oil film pressure, temperature, load capacity, Sommerfeld number and power loss characteristics across the bearing. The effect of ellipticity ratio on the bearing performance characteristics has also been obtained for both the elliptical and vertical offset bearing using three different commercially available grades of oil (Hydrol 32, 68 and 100). Findings It has been observed that the thermo-hydrodynamic pressure and temperature rise of the oil film is less in orthogonal bearing as compared to the true elliptical bearing for same operating conditions. The effect of ellipticity ratio of non-circularity on bearing performance parameters have been observed to be less in case of elliptical bearing as compared to orthogonal bearing. It has been concluded that though the rise in oil film temperature is high for true elliptical bearing, but still it should be preferred over orthogonal profile under study, as it has comparably good load-carrying capacity. Originality/value The performance parametric analysis will help the designers to select such kind of non-circular journal bearing for various applications.

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