Effect of pin generatrix on the elastohydrodynamic lubrication performance of pin-bush pair in industrial roller chains

2021 ◽  
pp. 135065012110659
Author(s):  
Ansheng Zhang ◽  
Jing Wang ◽  
Yiming Han ◽  
Jianjun Zhang ◽  
Yi Liu
Keyword(s):  
Film Thickness ◽  
Working Condition ◽  
Elastohydrodynamic Lubrication ◽  
Test Rig ◽  
Stroke Length ◽  
Oil Supply ◽  
Supply Condition ◽  
Lubrication Performance ◽  
Custom Made ◽  
Disk Test

For industrial roller or bush chains, the bush swings relative to the pin at working condition. If proper lubrication is maintained, an elastohydrodynamic lubrication contact is formed between the pin and the bush. In this study, a custom-made pin was used to replace the steel ball of a ball-disk test rig and optical interferometric experiments were carried out to study the effect of pin generatrix on the lubrication performance. The effects of generatrix shape, stroke length and oil supply condition on the lubrication state were explored. It is found that the change of the generatrix has an important influence on the oil film thickness, especially under rare oil supply condition.

Experimental Investigation of Lubricant Flow Properties Under Micro Oil Supply Condition

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Shanhua Qian ◽  
Dan Guo ◽  
Shuhai Liu ◽  
Xinchun Lu
Keyword(s):  
Film Thickness ◽  
Contact Region ◽  
Elastohydrodynamic Lubrication ◽  
Relative Length ◽  
Flow Properties ◽  
Oil Supply ◽  
Supply Condition ◽  
Lubricant Flow ◽  
Oil Pool ◽  
Disc Configuration

Lubricant flow properties of polyalphaolefin (PAO) oil have been experimentally investigated based on a ball-on-disc configuration under micro oil supply condition. The oil pool shape and central film thickness in the contact region were obtained using fluorescence microscopy and optical interferometry, respectively. It has been found that the relative length between the inlet meniscus and Hertzian center point in the oil pool to Hertzian radius was much larger than 1 in a smaller lubricant supply of 20 μl, and the corresponding contact region initially entered the elastohydrodynamic lubrication (EHL) region and then became starved with the increasing speed. The variations of the relative film thickness as a function of starvation degree and the ratio of relative length to Hertzian radius were proposed to explain the obtained results. Besides, the fluorescence technique was used to directly observe the inlet meniscus position of the oil pool and helped to gain more understanding of the lubricant flow properties under micro oil supply condition.

Effect of the Shape of Inlet Oil-Supply Layer on Starved Lubrication Performance of a Cycloid Drive

2015 ◽  
Author(s):  
Caichao Zhu ◽  
Zhangdong Sun ◽  
Huaiju Liu ◽  
Chaosheng Song ◽  
Zufeng Li ◽  
...  
Keyword(s):  
Film Thickness ◽  
Fatigue Behavior ◽  
Contact Fatigue ◽  
Elastohydrodynamic Lubrication ◽  
Mechanical Efficiency ◽  
Grease Lubrication ◽  
Oil Film ◽  
Oil Supply ◽  
Lubrication Performance ◽  
Starved Lubrication

The lubrication performances of cycloid drives affect the dynamic characteristics, the mechanical efficiency and the contact fatigue behavior of the system. To maintain tranmission precision it is required to minimum the times of disassebly, hence grease lubrication is often applied where starvation might occur in service. Starved lubrication performance of a cycloid gear drive is studied using a numerical finte line starved-elastohydrodynamic lubrication model. The parameter of the inlet oil film thickness is chosen to represent the starved status. Effects of the inlet film thickness on the centralfilm thickness, the friction coefficient and the frictional power loss are investigated. In addition, effects of different shape of inlet oil-supply layer in the same starved degree on lubrication performance are studied. Under the same inlet oil supply volume, the convex type profile would present a better oil film within the nominal contact zone compared with other four different shapes of the inlet film supply.

A Starved Mixed Elastohydrodynamic Lubrication Model for the Prediction of Lubrication Performance, Friction and Flash Temperature With Arbitrary Entrainment Angle

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Wei Pu ◽  
Dong Zhu ◽  
Jiaxu Wang
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Flash Temperature ◽  
Machined Surface ◽  
Lubrication Performance ◽  
Wide Range ◽  
Starved Lubrication

In this study, a modified mixed lubrication model is developed with consideration of machined surface roughness, arbitrary entraining velocity angle, starvation, and cavitation. Model validation is executed by means of comparison between the obtained numerical results and the available starved elastohydrodynamic lubrication (EHL) data found from some previous studies. A comprehensive analysis for the effect of inlet oil supply condition on starvation and cavitation, mixed EHL characteristics, friction and flash temperature in elliptical contacts is conducted in a wide range of operating conditions. In addition, the influence of roughness orientation on film thickness and friction is discussed under different starved lubrication conditions. Obtained results reveal that inlet starvation leads to an obvious reduction of average film thickness and an increase in interasperity cavitation area due to surface roughness, which results in significant increment of asperity contacts, friction, and flash temperature. Besides, the effect of entrainment angle on film thickness will be weakened if the two surfaces operate under starved lubrication condition. Furthermore, the results show that the transverse roughness may yield thicker EHL films and lower friction than the isotropic and longitudinal if starvation is taken into account. Therefore, the starved mixed EHL model can be considered as a useful engineering tool for industrial applications.

Prediction of transient lubricating film thickness in knee prostheses with compliant layers

1998 ◽  
Vol 212 (3) ◽  
pp. 157-164 ◽  
Author(s):  
Z M Jin ◽  
D Dowson ◽  
J Fisher ◽  
N Ohtsuki ◽  
T Murakami ◽  
...  
Keyword(s):  
Knee Joint ◽  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Contact Radius ◽  
Knee Prostheses ◽  
Stroke Length ◽  
Additional Advantage ◽  
Lubricating Film ◽  
Theoretical Predictions ◽  
Lubricating Film Thickness

The transient lubricating film thickness in knee prostheses using compliant layers has been predicted under simulated walking conditions based upon the elastohydrodynamic lubrication theory. Qualitative agreement has been found between the present theoretical predictions and the experimental measurements using an electric resistance technique reported earlier. It has been shown that the contact geometry plays an important role in the generation of fluid film lubrication in knee prostheses using compliant layers. The maximum lubricating film thickness is predicted for the maximized contact area of a transverse conjunction where the semi-minor contact radius lies in the direction of entraining. The additional advantage of the transverse contact conjunction is that the possibility of lubricant starvation due to small stroke length can be minimized. All these factors, together with the kinematic requirements in the natural knee joint, should be taken into consideration when designing artificial knee joint replacements.

scholarly journals Marine Four-Stroke Diesel Engine Crankshaft Main Bearing Oil Film Lubrication Characteristic Analysis

2018 ◽  
Vol 25 (s2) ◽  
pp. 30-34
Author(s):  
Teng Xian Bin ◽  
Zhang Jun Dong
Keyword(s):  
Diesel Engine ◽  
Film Thickness ◽  
Dynamic Pressure ◽  
Synthesis Method ◽  
Elastohydrodynamic Lubrication ◽  
Characteristic Analysis ◽  
Main Bearing ◽  
Oil Film ◽  
Modal Synthesis ◽  
Lubrication Performance

Abstract The Craig-Bampton modal synthesis method was used to establish the dynamic model of marine four-stroke diesel engine body and crankshaft. Based on the Greenwood/Tripp microlong contact theory considering the surface roughness and the generalized Reynolds equation considering the oil filling rate, the elastohydrodynamic lubrication model of the main bearing of the four - stroke diesel engine is found. At the rated speed, the lubrication performance of the main bearing is simulated and analyzed by the maximum dynamic pressure, the minimum oil film thickness and the friction power. The results show that the oil pressure of 4 # main bearing is the largest and the maximum oil film pressure is in the 4 # main bearing position. The friction load of 4 # main bearing is the largest. The average oil film thickness of 4 # main bearing is the smallest and the minimum oil film The thickness also occurred in the 4 # main bearing position; it can be seen 4 # bearing the most bad lubrication conditions.

Thermal Elastohydrodynamic Lubrication of Axially Crowned Rollers

2021 ◽  
pp. 1-21
Author(s):  
Wassim Habchi
Keyword(s):  
Film Thickness ◽  
Design Parameter ◽  
Numerical Study ◽  
Elastohydrodynamic Lubrication ◽  
Negative Influence ◽  
Reference Case ◽  
Critical Design ◽  
Lubrication Performance ◽  
Minimum Film Thickness ◽  
Line Contacts

Abstract This work presents a comprehensive numerical study of thermal elastohydrodynamic lubrication performance in axially crowned rollers, based on a full-system finite element approach. Axial crowning has always been introduced to finite line contacts, as a mean for improving film thickness. Its influence on friction has often been overlooked though. The current work reveals that axial crowning has a negative influence on friction, increasing it significantly with respect to the reference case of straight rollers. It is shown that, with increased crowning height (or reduced crowning radius), minimum film thickness is increased, but so is friction. Therefore, film thickness enhancement comes at the expense of a deterioration in friction. Besides, achieving sufficient enhancements in minimum film thickness would require using relatively low crowning radii, which would lead to a substantial increase in friction. The frictional increase is traced back to an overall increase in contact pressures and effective contact area within the lubricating conjunction. It is also shown that, when film thickness is the most critical design parameter, the best compromise between enhanced film thickness and deteriorated friction would be to combine axial crowning with roller-end profiling. However, when friction is the most critical design parameter, a simple roller-end profiling would offer the best compromise.

Elastohydrodynamic Lubrication Analysis of Point Contacts With Consideration of Material Inhomogeneity

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Zhang Shengguang ◽  
Wang Wenzhong ◽  
Zhao Ziqiang
Keyword(s):  
Film Thickness ◽  
Numerical Algorithms ◽  
Elastohydrodynamic Lubrication ◽  
Rolling Bearing ◽  
Inclusion Problem ◽  
Material Inhomogeneity ◽  
Equivalent Inclusion Method ◽  
Lubrication Performance ◽  
The Matrix ◽  
Lubricated Contact

Inhomogeneities in matrix may significantly affect the performance of mechanical elements, such as possible fatigue life reduction for rolling bearing due to stress concentration induced by inhomogeneities; on the other hand, most components operate under lubrication environment. So far the numerical algorithms to solve lubrication problems without the consideration of inhomogeneities or inclusions are well developed. In this paper, the combination of elastohydrodynamic lubrication (EHL) and inclusion problem is realized to consider the effect of material inhomogeneity on the lubrication performance and subsurface stress distribution, etc. The matrix inhomogeneity will induce disturbed displacement, which will modify the film thickness and consequently result in the change of lubricated contact pressure distribution, etc. The matrix inhomogeneity is treated as the homogeneous inclusion with equivalent eigenstrain according to equivalent inclusion method (EIM), and the disturbed displacement is calculated by semi-analytical method (SAM). While the pressure and film thickness distributions are obtained by solving Reynolds equation. The iterative process is realized to consider the interaction between lubrication behavior and material response. The results show the inhomogeneity in contacting body will greatly influence the lubricated contact performance. The influences are different between compliant and stiff inhomogeneity. It is also found that different sizes and positions of inhomogeneity can significantly affect the contact characteristic parameters.

Coupling analysis of the fatigue life and the TEHL contact behavior of ball screw under the multidirectional load

2020 ◽  
Vol 72 (10) ◽  
pp. 1285-1293
Author(s):  
Jia-Jia Zhao ◽  
Ming-Xing Lin ◽  
Xian-Chun Song ◽  
Nan Wei
Keyword(s):  
Fatigue Life ◽  
Film Thickness ◽  
Peer Review ◽  
Elastohydrodynamic Lubrication ◽  
Contact Model ◽  
Ball Screw ◽  
Content Type ◽  
Entrainment Velocity ◽  
Contact Points ◽  
Lubrication Performance

Purpose This paper aims to provide thermal elastohydrodynamic lubrication (TEHL) contact model to study all balls’ lubrication performance of the ball screw when the multidirectional load is applied. Design/methodology/approach A new TEHL contact model combining the multidirectional load and the roughness surface texture is established to describe fatigue life of the ball screw. Meanwhile, the authors use the Reynolds equation to study the lubrication performance of the ball screw. Findings When the multidirectional load is applied, contact load, slide-roll ratio and entrainment velocity of all balls have a periodic shape. The TEHL performance values at the ball-screw contact points including contact stress, shear stress, minimum film thickness and temperature rise are higher than that at the ball-nut contact points. The TEHL performance values increase with the increase of root mean square (RMS) except for the film thickness. In addition, the radial load of the ball screw has a significant effect on the fatigue life. Originality/value The results of the studies demonstrate the new TEHL contact model that provides the instructive significance to analyze the fatigue life of the ball screw under the multidirectional load. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2020-0097/

Study on the Micro Thermal EHL Behavior of Wind Turbine Gearbox

2011 ◽  
Vol 86 ◽  
pp. 443-447
Author(s):  
Bin Wu ◽  
Wan Kai Shi ◽  
Long Zhao ◽  
Ping Fu
Keyword(s):  
Film Thickness ◽  
Wind Turbine ◽  
Elastohydrodynamic Lubrication ◽  
Surface Damage ◽  
Pressure Profile ◽  
Thickness Ratio ◽  
Tooth Surface ◽  
Roughness Effects ◽  
Wind Turbine Gearbox ◽  
Lubrication Performance

A complete numerical solution for the micro thermal elastohydrodynamic lubrication (EHL) of planetary gearing in wind turbine gearbox is obtained with taking roughness effects and characteristics of non-Newtonian fluids into account. The oil film pressure profile, film shape and the trend of equivalent temperature rise in planetary gearing in special meshing points are drawn. Through comparing with lubrication performance in different surface morphology between Ra=0.8μm and 0.2μm, the results show that the film thickness ratio of ring gear and planetary gears with Ra=0.8μm is greatly smaller than 1.5. From the relationship between tooth surface damage and film thickness ratio, these gears are in abnormal lubrication state, surface damage, when Ra=0.8μm, can theoretically reach more than 15%. However, the surface damage ratio with Ra=0.2μm has been greatly deceased, so as to that it provides a theoretical basis of reliable lubrication analysis for wind turbine gearbox.

Design and Experiment Study on a New Type of Lubrication Simulation System for Thrust-Ball Bearing in Confined Space

2017 ◽  
Vol 873 ◽  
pp. 303-307
Author(s):  
Feng Li ◽  
Feng Guo ◽  
Guan Gyuan Liu ◽  
Zhang Gang
Keyword(s):  
Film Thickness ◽  
Ball Bearing ◽  
Elastohydrodynamic Lubrication ◽  
Simulation System ◽  
Operating Conditions ◽  
Confined Space ◽  
Entrainment Velocity ◽  
Lubrication Performance ◽  
New Type ◽  
The Relationship

Many machine components work within an elastohydrodynamic lubrication (EHL) regime. Unconfined space is widely used in EHL formulas for to evaluate film thickness, which is related to operating conditions and material properties. In classical theoretical EHL studies, film pressure matches the loading balance and the location of the lubricated components can be adjusted. In the present study, the lubrication performance is analyzed based on a confined space. A thrust ball bearing lubrication simulation system is designed and used to examine the relationship between velocity and film thickness. It was found that the central film thickness and minimum film thickness increased as entrainment velocity increased. Fluctuations in the film thickness curve were observed, which may have arisen from slight gap variations in the ball-plate contact area.

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