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.

An Investigation Into the Influence of Fluid Viscoelasticity in a Squeeze Film Bearing

1978 ◽  
Vol 100 (1) ◽  
pp. 56-64 ◽  
Author(s):  
John A. Tichy ◽  
Ward O. Winer
Keyword(s):  
Molecular Weight ◽  
Film Thickness ◽  
High Molecular Weight ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Surface Film ◽  
Free Fall ◽  
Squeeze Film ◽  
Delayed Response ◽  
High Molecular Weight Polymers

This investigation concerns a prediction of the behavior of viscoelastic fluids in a parallel circular squeeze film with a constant approach velocity, and a comparison to experimental results. The squeeze film geometry has direct application to unsteady hydrodynamic lubrication. The analysis predicts that load capacity of a viscoelastic fluid may be increased due to normal stress effects or decreased due to a delayed response of shear stress to a change in shear rate. Ten tested fluids include Newtonian control fluids, silicone fluids, high molecular weight polymers in petroleum oils, and extremely high molecular weight polymers in water and glycerin. The experimental squeezing is accomplished by the free fall of a cylindrical steel rod along its axis toward a stationary opposing surface. Film thickness, velocity of approach and load are measured. The velocity of approach is essentially constant in the range of film thickness considered. The water-glycerin-polymer solutions exhibited load capacity increases up to 33 percent, while the petroleum-polymer and silicone fluids showed decreases to 23 percent. It appears that viscoelastic effects cannot account for the reported improved bearing performance of polymer-additive lubricants.

Numerical Simulation on the Lubrication Performance of Surface Textured Piston Rings

2011 ◽  
Vol 199-200 ◽  
pp. 734-738 ◽  
Author(s):  
Qiu Ying Chang ◽  
Xian Liang Zheng ◽  
Qing Liu
Keyword(s):  
Numerical Simulation ◽  
Film Thickness ◽  
Friction Force ◽  
Friction And Wear ◽  
Piston Ring ◽  
Hydrodynamic Lubrication ◽  
Cylinder Liner ◽  
Area Density ◽  
Oil Film ◽  
Lubrication Performance

Surface texturing has been successfully employed in some tribological applications in order to diminish friction and wear. This technology may be used in a piston ring to decrease the friction and wear of the contact between a piston ring and cylinder liner. A numerical simulation of lubrication between a surface textured piston ring and cylinder liner based on the hydrodynamic lubrication theory was conducted. The influence of surface texture parameters on piston ring lubrication performance was obtained by solving the mathematical equations with a multi-grid method. The results show that under the micro-dimple area density of 5%-40% the minimum oil film thickness increases and the dimensionless friction force decreases with the increasing of it. Under the dimple area density of 40%-60%, the minimum oil film thickness and the dimensionless friction force change slightly. Under various dimple area densities the optimum dimple depth at the given working condition in this paper is about 5µm.

Analysis of a Plane Inclined Guide Bearing Under Transverse Vibration and Translation of a Plate

1983 ◽  
Vol 105 (3) ◽  
pp. 335-341 ◽  
Author(s):  
Y. D. Murray ◽  
C. D. Mote
Keyword(s):  
Film Thickness ◽  
Velocity Distribution ◽  
Friction Force ◽  
Transverse Vibration ◽  
Load Capacity ◽  
Lubrication Theory ◽  
Plate Vibration ◽  
Parabolic Profile ◽  
Lubricant Flow

Analysis of the load capacity, friction force, and lubricant flow of a infinite width, plane guide during transverse vibration and translation of a plate is presented. The effect of lubricant inertia on these variables is investigated and found to be significant. Analysis is facilitated through assumption of a parabolic velocity distribution across the film thickness as suggested by lubrication theory. The parabolic profile assumption is found to underestimate the contribution of lubricant inertia to the load capacity during plate vibration.

Hydrodynamic Lubrication of a Porous Slider

1973 ◽  
Vol 15 (3) ◽  
pp. 232-234 ◽  
Author(s):  
J. Prakash ◽  
S. K. Vij
Keyword(s):  
Drag Coefficient ◽  
Closed Form ◽  
Coefficient Of Friction ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Centre Of Pressure ◽  
Slider Bearing ◽  
Frictional Drag ◽  
Pressure Load ◽  
The Coefficient Of Friction

A plane porous slider bearing is analysed and closed form expressions for pressure, load, frictional drag, coefficient of friction and centre of pressure are obtained. The effect of porosity is to decrease the load capacity and friction. However, the coefficient of friction is increased.

Study of the influence of lubrication parameters on gear lubrication properties and efficiency

2016 ◽  
Vol 68 (6) ◽  
pp. 647-657 ◽  
Author(s):  
Kaiyue Li ◽  
Guoding Chen ◽  
Deng Liu
Keyword(s):  
Power Consumption ◽  
Film Thickness ◽  
High Speed ◽  
Hydrodynamic Lubrication ◽  
Quantitative Relationship ◽  
Gear Transmission ◽  
Content Type ◽  
Oil Film ◽  
Friction Power ◽  
Lubricating Properties

Purpose The analysis of lubricating properties and efficiency is important for aviation high-speed gear. So far, the project of lubricating properties and efficiency are processing under the condition of a given lubricating state, which is still depending on practical experience. This paper aims to mostly focus on the analysis of given lubricating state but lost sight of the relevance of lubrication parameters and lubricating state, which not only makes the analysis of aviation high-speed gear transmission and efficiency fail to trace to practical situation but also has an adverse effect on the reliance and validity of the project. Design/methodology/approach Based on this, the numerical model of spraying oil and oil film spreading is established, and the quantitative relationship between spray lubrication parameters and spreading characteristics of oil film is studied. According to the geometric and mechanical conditions of meshing points and taking the influence of rich-oil/starved-oil lubrication and roughness of teeth surface into consideration, corrected film thickness under condition of elasto-hydrodynamic lubrication and lubricating state of mesh points are analyzed. On this basis, power consumption and efficiency of gear transmission are also calculated by figuring out the solid friction and oil friction separately. Findings Through the research of this thesis, the effect of friction power consumption and efficiency with lubrication parameters is discussed. The effect of lubrication parameters on friction power consumption and efficiency of gear is complex. With the increase of spreading film thickness and film length, the frictional power consumption is less and the efficiency is higher. Originality/value This work provides a systematic technological approach to lubrication design and efficiency calculation of aviation high-speed gear transmission, which has remarkable engineering significance for the accurate lubrication design of the aviation mechanical parts.

scholarly journals Friction Characteristics of Liquid Lubricated MEMS with Deterministic Boundary Slippage

2014 ◽  
Vol 66 (3) ◽  
Author(s):  
Mohammad Tauviqirrahman ◽  
Muchammad Muchammad ◽  
Rifky Ismail ◽  
Jamari Jamari ◽  
Dik J. Schipper
Keyword(s):  
Film Thickness ◽  
Beneficial Effect ◽  
Friction Force ◽  
Coefficient Of Friction ◽  
Reynolds Equation ◽  
Friction Reduction ◽  
Hydrodynamic Performance ◽  
Friction Characteristics ◽  
Reduction Mechanisms ◽  
Boundary Slippage

It has been proven experimentally that boundary slippage represents a viable effect on the hydrodynamic performance of lubricated sliding contacts. Along with several friction reduction mechanisms that have been explored in the literature, the slippage parameters remain an important feature. With the main objective of evaluating the effects of the slippage, a modified Reynolds equation is employed. The result shows that deterministic boundary slippage of the lubricated-MEMS with uniform film thickness has a very beneficial effect on decreasing friction force as well as coefficient of friction.

Geometrical analysis of elliptical journal bearings and its effects on friction and load capacity

2019 ◽  
Vol 234 (5) ◽  
pp. 743-750
Author(s):  
Ali Ebrahimi ◽  
Saleh Akbarzadeh ◽  
Hassan Moosavi
Keyword(s):  
Friction Force ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Major Axis ◽  
Journal Bearings ◽  
Maximum Pressure ◽  
Geometrical Parameters ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Lower Temperature

Elliptical bearings are one type of non-circular journal bearings which has two main advantages over the conventional circular bearings: lower temperature rise and lower vibrations. In this study, the energy equation and Reynolds equation are simultaneously solved under adiabatic boundary conditions. The predicted pressure and temperature are compared to the results of published literature for verification purposes. A parametric study is then conducted on the effect of geometrical parameters of the elliptical journal bearing on the load capacity, friction force, pressure, and oil temperature. Effect of geometric parameters of the bearing on the performance is studied. The results show that non-circularity parameter is the most influential parameter in the bearing, and an increase in the non-circularity results in the decrease in maximum pressure and temperature as well as the friction force. Increasing the eccentricity ratio, on the other hand, will cause an increase in the pressure, temperature, and the friction force. Changes in the angle between the major axis of the bearing and load direction decrease the load-carrying capacity and the non-dimensional pressure and results in an increase in the friction coefficient.

Evaluation on Applicability of Reynolds Equation for Squared Transverse Roughness Compared to CFD

2007 ◽  
Vol 129 (4) ◽  
pp. 963-967 ◽  
Author(s):  
Jiang Li ◽  
Haosheng Chen
Keyword(s):  
Film Thickness ◽  
Reynolds Equation ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Roughness Height ◽  
Obvious Effect ◽  
Disk Interface ◽  
Transverse Roughness ◽  
The Difference ◽  
Cfd Method

A discrete probability distribution function is used to represent the squared transverse roughness effect in a modified Reynolds equation, and the Reynolds equation is used to calculate the hydrodynamic lubrication in a slider-disk interface compared to the CFD method. When the roughness height is below 1% of the film thickness, the results acquired by the two methods are the same and the surface roughness does not show obvious effect on the lubrication results compared to that on the smooth surface. The load capacity and friction force increase as the roughness height increases when the roughness height exceeds 1% of the film thickness. Moreover, the forces acquired by Reynolds equations are smaller than those acquired by CFD, and the difference between them exceeds 10% when the roughness height is higher than 10% of the film thickness. Sidewall effect is considered to be the main reason for the difference, and the Reynolds equation is believed not suitable for calculating the effect of the squared transverse roughness in the hydrodynamic lubrication.

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.

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