Effects of Working Conditions on TEHL Performance of a Helical Gear Pair With Non-Newtonian Fluids

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Mingyong Liu ◽  
Caichao Zhu ◽  
Huaiju Liu ◽  
Huafeng Ding ◽  
Zhangdong Sun
Keyword(s):  
Working Conditions ◽  
Power Law ◽  
Elastohydrodynamic Lubrication ◽  
Helical Gear ◽  
Gear Pair ◽  
Power Law Fluid ◽  
Finite Line Contact ◽  
Lubrication Performance ◽  
Finite Line ◽  
Helical Gear Pair

A thermal elastohydrodynamic lubrication (TEHL) finite line contact model is developed for a helical gear pair lubricated with an Eyring fluid or a power-law fluid in order to investigate the effects of the working conditions. A lubrication analysis within a meshing period shows that the differences between the Eyring and Newtonian solutions mainly lie in the film temperature and the shear stress. For the power-law fluid, the power index n has a significant effect on the film thickness. The effects of load and speed on lubrication performance along the line of action are discussed.

scholarly journals A Micro-TEHL Finite Line Contact Model for a Helical Gear Pair

2014 ◽  
Vol 7 (1) ◽  
pp. 104790 ◽  
Author(s):  
Mingyong Liu ◽  
Caichao Zhu ◽  
Huaiju Liu
Keyword(s):  
Helical Gear ◽  
Contact Model ◽  
Gear Pair ◽  
Line Contact ◽  
Finite Line Contact ◽  
Finite Line ◽  
Helical Gear Pair

A thermal finite line contact EHL model of a helical gear pair

2012 ◽  
Vol 227 (4) ◽  
pp. 299-309 ◽  
Author(s):  
Caichao Zhu ◽  
Mingyong Liu ◽  
Huaiju Liu ◽  
Xiangyang Xu ◽  
Libin Liu
Keyword(s):  
Helical Gear ◽  
Gear Pair ◽  
Line Contact ◽  
Finite Line Contact ◽  
Finite Line ◽  
Helical Gear Pair

Subsurface stress-field analysis of generating ground helical gear based on finite line-contact mixed elastohydrodynamic lubrication

2020 ◽  
Vol 235 (1) ◽  
pp. 3-17
Author(s):  
Zonglin Gu ◽  
Caichao Zhu ◽  
Huaiju Liu ◽  
Jinyuan Tang
Keyword(s):  
Surface Roughness ◽  
Stress Field ◽  
Smooth Surface ◽  
Elastohydrodynamic Lubrication ◽  
Helical Gear ◽  
Tooth Surface ◽  
Finite Line Contact ◽  
Finite Line ◽  
Subsurface Stress ◽  
Maximum Stresses

Tooth surface roughness and lubrication status have significant influence on the contact performance and fatigue life of helical gear pair. Yet, despite the development in elastohydrodynamic lubrication-based contact analysis and solution of subsurface stress field, researches in subsurface stress field of helical gears considering both lubrication and surface roughness are not quite comprehensive. In this study, three-dimensional surface roughness of generating ground gear is measured, a finite line-contact mixed elastohydrodynamic lubrication model is established to perform the contact analysis, and, on this basis, the influence of tooth surface roughness on the subsurface stress field is studied. Results show that compared with the smooth surface, the overall level of subsurface stress is raised; maximum stress values and plastic zones occur in the close vicinity of tooth surface, which adds to the risk of surface failure; within sections in the valley regions of roughness, locations of maximum stresses are generally similar to the smooth surface situation, i.e. in relatively deep zones, while within sections in the peak regions, the majority of locations with maximum stresses shift much closer to the surface; contact pressure and stress status see only mild undulation between different sections distributed along the contact line, but intense changes between sections distributed along the entraining direction.

scholarly journals Predicting Fatigue Life for Finite Line Contact under Starved Elastohydrodynamic Lubrication Condition

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Mingyong Liu ◽  
Haofeng Ku ◽  
Jinxi Zhang ◽  
Peidong Xu ◽  
Chenhui Wu
Keyword(s):  
Fatigue Life ◽  
Contact Fatigue ◽  
Elastohydrodynamic Lubrication ◽  
Operating Conditions ◽  
Line Contact ◽  
Finite Line Contact ◽  
Lubrication Performance ◽  
Finite Line ◽  
Lubrication Condition ◽  
Lubrication Characteristics

Surface contact fatigue is the main failure mode in many mechanical components, such as gears, bearings, and cam-followers. A fatigue life prediction model is proposed for finite line contact under starved thermal elastohydrodynamic lubrication (TEHL) condition in this paper. Then, the effects of inlet oil-supply thickness, slide-to-roll ratio (SRR), and operating conditions on the lubrication performance and fatigue life are investigated. The results show that the lubrication characteristics and fatigue life of finite line contact are obviously different from those of fully flooded situation by introducing the starved lubrication condition. For example, the severe starved conditions lead to a significant increase in friction coefficient and decreased fatigue life. The variation of SRR has an important influence on the fatigue life. With the increase of SRR, the fatigue life decreases firstly and then increases. The stress concentration occurs near the surface when speed is low. In addition, under the low-speed situation, rotation speed variation has little effect on the fatigue life.

Thermal elastohydrodynamic lubrication analysis of helical gear pair under starved lubrication condition

2019 ◽  
Vol 31 (7) ◽  
pp. 321-334 ◽  
Author(s):  
Mingyong Liu ◽  
Jinxi Zhang ◽  
Peidong Xu ◽  
Hao Cai ◽  
Haofeng Ku ◽  
...  
Keyword(s):  
Elastohydrodynamic Lubrication ◽  
Helical Gear ◽  
Gear Pair ◽  
Lubrication Condition ◽  
Starved Lubrication ◽  
Helical Gear Pair

Analysis of mechanical power loss of a helical gear pair based on the starved thermal-elastohydrodynamic lubrication model

2019 ◽  
Vol 72 (3) ◽  
pp. 333-340
Author(s):  
Mingyong Liu ◽  
Peidong Xu ◽  
Jinxi Zhang ◽  
Huafeng Ding
Keyword(s):  
Surface Roughness ◽  
Tribological Properties ◽  
Power Loss ◽  
Elastohydrodynamic Lubrication ◽  
Helical Gear ◽  
Mechanical Power ◽  
Gear Pair ◽  
Content Type ◽  
Helical Gear Pair ◽  
Film Lubrication

Purpose Power loss is an important index to evaluate the transmission performance of a gear pair. In some cases, the starved lubrication exists on the gear contact interface. The purpose of this paper is to reveal the mechanical power loss of a helical gear pair under starved lubrication. Design/methodology/approach A starved thermal-elastohydrodynamic lubrication (EHL) model is proposed to evaluate the tribological properties of a helical gear pair. The numerical result has been validated against the published simulation data. Based on the proposed model, the influence of thermal effect, working conditions, inlet oil-supply layer and surface roughness on the mechanical power loss and lubrication performance has been discussed. Findings Results show that the thermal effect has a significant effect on the tribological properties of helical gear pair, especially on mechanical power loss. For a specified working condition, there is an optimal oil supply for gear lubrication to obtain the state of full film lubrication. Meanwhile, it reveals that the mechanical power loss increases with the increase of the surface roughness amplitude. Originality/value In this paper, a starved thermal-EHL model has been developed for the helical gear pair based on the finite line contact theory. This model can be used to analyze the tribological properties of gear pair from full film lubrication to mixed lubrication. The results can provide the tribological guidance for design of a helical gear pair.

A calculation method of sliding friction coefficient on tooth surface for helical gear pair based on loaded tooth contact analysis and elastohydrodynamic lubrication theory

2020 ◽  
pp. 135065012096689
Author(s):  
Cheng Wang ◽  
Mao Ken
Keyword(s):  
Friction Coefficient ◽  
Sliding Friction ◽  
Elastohydrodynamic Lubrication ◽  
Helical Gear ◽  
Tooth Surface ◽  
Gear Pair ◽  
Tooth Contact Analysis ◽  
Sliding Friction Coefficient ◽  
Loaded Tooth Contact Analysis ◽  
Helical Gear Pair

The sliding friction coefficient on tooth surface is related to power loss, carry capacity and transmission performance of gear. Reasonable transmission analysis of gear pair is the premise of accurate calculation of sliding friction coefficient on tooth surface. However, for helical gear pair, the line contact without considering machining error/installation error/modification of gear is usually adopted to replace the major axis of ellipse caused by contact load. Therefore, in this paper, contact path on tooth surface, length of contact line, load distribution on tooth surface and loaded transmission errors are accurately calculated by loaded tooth contact analysis (LTCA). Combing with elastohydrodynamic lubrication (EHL) theory, a calculation method of sliding friction coefficient on tooth surface for helical gear pair is proposed.

Lubrication performance of helical gear pair under dynamic load based on local involute profile

2021 ◽  
pp. 1-16
Author(s):  
Mingyong Liu ◽  
Yang Qu ◽  
Chenglong Hu ◽  
Enxi Deng
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Tribological Properties ◽  
Dynamic Load ◽  
Helical Gear ◽  
Tooth Profile ◽  
Tooth Surface ◽  
Gear Pair ◽  
Lubrication Performance ◽  
Helical Gear Pair

Abstract The tribological properties of gear interface have been widely concerned in the past decades. In this study, based on the local involute profile and crown modification, a thermal elastohydrodynamic lubrication model is proposed for a helical gear pair. To discuss the influences of dynamic load on the tribological properties of helical gear pair, the dynamic mesh force of tooth surface is obtained by torsional vibration model. The influences of working conditions and surface roughness on the tribological properties of helical gear pair are investigated. The tribological properties are evaluated in terms of the average film thickness, friction coefficient, mechanical power loss etc. Results show that the dynamic effect of gears has a significant effect on the tribological properties, especially at a specific speed, such as resonance speed. In order to simulation gear lubrication accurately, it is recommended to adopt local involute tooth profile and consider tooth profile modification to calculate geometric clearance. The influence of input rotation speed on the dynamic characteristics and tribological properties of gear is more significant than that of input torque. The surface roughness significantly changes the distribution of interface pressure and film thickness. With the increase of roughness amplitude, the local fluctuation amplitude of pressure and film thickness increase and the dry contact occurs at the end of contact line. Meanwhile, the maximum subsurface stress moves toward the tooth surface, especial for the high frequency engineering roughness. This local stress concentration is harmful to the fatigue life of gear meshing process.

Parametric Studies of Mechanical Power Loss for Helical Gear Pair Using a Thermal Elastohydrodynamic Lubrication Model

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Mingyong Liu ◽  
Peidong Xu ◽  
Chunai Yan
Keyword(s):  
Friction Coefficient ◽  
Thermal Effect ◽  
Power Loss ◽  
Elastohydrodynamic Lubrication ◽  
Mechanical Efficiency ◽  
Helical Gear ◽  
Tribological Performance ◽  
Mechanical Power ◽  
Gear Pair ◽  
Helical Gear Pair

In this study, a comprehensive mechanical efficiency model based on the thermal elastohydrodynamic lubrication (TEHL) is developed for a helical gear pair. The tribological performance of the helical gear pair is evaluated in terms of the average film thickness, friction coefficient, mechanical power loss, mechanical efficiency, etc. The influence of basic design parameters, working conditions, thermal effect, and surface roughness are studied under various transmission ratios. Results show that the contribution of thermal effect on the tribological performance is remarkable. Meanwhile, the rolling power loss constitutes an important portion of the total mechanical power loss, especially around the meshing position where the pitch point is located in the middle of contact line and the full elastohydrodynamic lubrication (EHL) state with the friction coefficient less than 0.005. The proper increase of normal pressure angle and number of tooth can improve the tribological performance. The influence of helix angle on the mechanical efficiency is less significant. A positive addendum modification coefficient for pinion and a negative addendum modification coefficient for wheel are good for improving the mechanical efficiency. The results provide the tribological guidance for design of a helical gear pair in engineering.

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