Effect of Crack on Elasto-hydrodynamic Lubrication in Point Contact

2021 ◽  
Author(s):  
Yujuan Li ◽  
Wen Wang ◽  
Mingfei Ma ◽  
Yongqiang Wang
Keyword(s):  
Hydrodynamic Lubrication ◽  
Point Contact

scholarly journals Theoretical model of the effect of dimple on friction behavior in hydrodynamic lubrication regime

2021 ◽  
Vol 264 ◽  
pp. 04076
Author(s):  
Auezhan Amanov ◽  
Xasan Turkmenov
Keyword(s):  
Theoretical Model ◽  
Hydrodynamic Lubrication ◽  
Renewable Energy Sources ◽  
Point Contact ◽  
Friction Behavior ◽  
Mechanical Parts ◽  
Research Areas ◽  
Lubrication Regime ◽  
Rigid Smooth ◽  
Film Lubrication

In this paper, full-film lubrication between the rigid smooth and dimpled surfaces was addressed. A theoretical model is developed to study the effect of a dimple on friction where the smooth surface is rotating while the dimpled surface is at rest. To simplify the problem, the magnified dimple cell is investigated along with some assumptions. Because dimples deploy periodically along with the x and y directions, the lubricant pressure also deploys periodically. A theoretical model can be developed for one cell and then extended to the whole surface. The main goal of this study is to understand the dimple effect on friction in a hydrodynamic lubrication regime. The main applications of this model are several types of bearings (point contact, line contact etc.) and mechanical parts where two surfaces interact in relative motion. Findings the optimum dimensions for the dimples also seem to be one of the interesting research areas in mechanization of agricultural and renewable energy sources.

scholarly journals Analysis of Starvation Effects on Hydrodynamic Lubrication in Nonconforming Contacts

1982 ◽  
Vol 104 (3) ◽  
pp. 410-417 ◽  
Author(s):  
D. E. Brewe ◽  
B. J. Hamrock
Keyword(s):  
Film Thickness ◽  
Hydrodynamic Lubrication ◽  
Three Dimensional ◽  
Point Contact ◽  
Sharp Decrease ◽  
Reduction Factor ◽  
Wide Range ◽  
Minimum Film Thickness ◽  
Contour Plots ◽  
Starvation Effects

Numerical methods were used to determine the effects of lubricant starvation on the minimum film thickness under conditions of a hydrodynamic point contact. Starvation was effected by varying the fluid inlet level. The Reynolds boundary conditions were applied at the cavitation boundary and zero pressure was stipulated at the meniscus or inlet boundary. The analysis is considered valid for a range of speeds and loads for which thermal, piezoviscous, and deformation effects are negligible. It is applied to a wide range of geometries (i.e., from a ball-on-plate configuration to a ball in a conforming groove). Seventy-four cases were used to numerically determine a minimum-film-thickness equation as a function of the ratio of dimensionless load to dimensionless speed for varying degrees of starvation. From this, a film reduction factor was determined as a function of the fluid inlet level. Further, a starved fully flooded boundary was defined and an expression determining the onset of starvation was derived. As the degree of starvation was increased, the minimum film thickness decreased gradually until the fluid inlet level became critical. Reducing the fluid inlet level still further led to a sharp decrease in the minimum film thickness. An expression determining the critically starved fluid inlet level was derived. The changes in the inlet pressure buildup due to changing the available lubricant supply are presented in the form of three-dimensional isometric plots and also in the form of contour plots.

scholarly journals MAGNETIC LIQUID IN HYDRODYNAMIC LUBRICATION MODE OF SPHERICAL SURFACES

2016 ◽  
Vol 2016 (3) ◽  
pp. 90-93 ◽  
Author(s):  
Али Албагачиев ◽  
Ali Albagachiev ◽  
Владимир Данилов ◽  
Vladimir Danilov
Keyword(s):  
Hydrodynamic Lubrication ◽  
Point Contact ◽  
Hydrodynamic Theory ◽  
Magnetic Liquid ◽  
Magnetic Forces ◽  
Spherical Surfaces ◽  
Lubrication Layer ◽  
Lubrication Mode ◽  
Hydrodynamic Lubrication Theory ◽  
The Magnetic Field

From the position of the hydrodynamic lubrication theory are considered the peculiarities of magnetoliquid lubrication in a point contact determined with a complicated character of the interaction of hydrodynamic and magnetic forces in a lubrication layer. The pressure distribution in a lubrication layer of magnetic liquid is considered as a superposition of the augend and addend pr and pm induced with hydrodynamic and magnetic forces. The contribution of the constituent pr is described by Reynolds equation in accordance with the classic hydrodynamic theory. At the saturation of magnetic liquid the constituent pm is presented as a function of the magnetic field strength, saturation magnetization of magnetic liquid and its viscosity and also velocity of rolling. As a result of the solution of a hydrodynamic problem through a numerical method there are defined conditions under which a lubrication layer loses its stability that is followed with the loss of carrying capacity in areas with negative pressure. The dependences of resistance to rolling forces, and sliding ones in a contact of spherical surfaces.

scholarly journals Effect of Oil Temperature on Load Capacity and Friction Power Loss in Point Contact Elasto-hydrodynamic Lubrication

2019 ◽  
Vol 22 (3) ◽  
pp. 180-186
Author(s):  
Hassan S Fatehallah ◽  
Zaid S. Hammoudi ◽  
Lutfy Y. Zidane
Keyword(s):  
Film Thickness ◽  
Friction Force ◽  
Coefficient Of Friction ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Point Contact ◽  
Fortran Program ◽  
Maximum Pressure ◽  
Force Coefficient ◽  
Friction Power

This study presents a numerical analysis for point contact Elasto-hydrodynamic lubrication EHL. The oils used are (0W-30 and 10W-40) as lubricants. The pressure and film-thickness profiles for point contact EHL are evaluated. The aims of this study are to estimate the effect of oil’s temperature on friction force, coefficient of friction and load carrying capacity. By using FORTRAN program, the Forward-iterative method is used, to solve two dimensional (2D) EHL problem. The viscosity is updating in the solution by using Roeland’s model. After the convergence of pressure is done, the friction force, friction power losses, and friction coefficient are calculated. The temperature used ranges from (-20 to 120 oC). The results showed the film-thickness decreases with the increasing of temperature. Though the maximum pressure is not affected, only the pressure distribution and profile are changed, inlet pressure decreases and the pressure profile tends towards a hertzian (dry contact) one. The friction force and the coefficient of friction decrease with the increasing of temperature.

Analysis of Heating Performances for Ultra-High Speed Electric Spindle Bearings Based on the Energy Theory of TEHL in Point Contact State

2010 ◽  
Vol 37-38 ◽  
pp. 135-140
Author(s):  
Song Sheng Li ◽  
Zhi Hong Hu ◽  
Peng Zhou ◽  
Peng Chen ◽  
Xiao Yang Chen ◽  
...  
Keyword(s):  
High Speed ◽  
Hydrodynamic Lubrication ◽  
Point Contact ◽  
Rolling Bearing ◽  
Total Quality ◽  
Contact State ◽  
Ultra High Speed ◽  
Air Lubrication ◽  
To Come

To analyze the lubricating state and the heating performances of the spindle bearings in ultra-high speed electric spindles, taken the characteristics of oil-air lubrication into account and based on the theories about rolling bearing dynamics and thermal elasto-hydrodynamic lubrication in point contact state, a model was built with the energy method for analyzing the heating performances the ball elements on both raceways in spindle bearings. An equation was derived for calculating the total quality of heat produced in a bearing. The influences of some basic factors such as the running speed, the axial preload, the oil viscidity, the design contact angle of bearing, and the ball materials and so on are analyzed on the heating performances in a bearing. The results show that it is easy to come into being elasto-hydrodynamic lubrication state for a bearing running in an ultra high-speed and lubricated by oil-air. It is also shown that the higher speed is, the more the quality of heat produced inside the oil films in the elasto-hydrodynamic lubrication state will be, which will bring the bearings working conditions worse.

Point-contact spectroscopy of quasi-1D conductors with CDW

1999 ◽  
Vol 09 (PR10) ◽  
pp. Pr10-179-Pr10-181
Author(s):  
A. A. Sinchenko ◽  
Yu. I. Latyshev ◽  
S. G. Zybtsev ◽  
I. G. Gorllova
Keyword(s):  
Point Contact ◽  
Point Contact Spectroscopy
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