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.

Numerical Modeling of Mixed Lubrication and Flash Temperature in EHL Elliptical Contacts

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Neelesh Deolalikar ◽  
Farshid Sadeghi ◽  
Sean Marble
Keyword(s):  
Surface Deformation ◽  
Elastohydrodynamic Lubrication ◽  
Mixed Lubrication ◽  
Asperity Contact ◽  
Lubrication Regime ◽  
Predicting Performance ◽  
Pure Rolling ◽  
Rolling Element ◽  
Contact Pressures ◽  
Film Lubrication

Highly loaded ball and rolling element bearings are often required to operate in the mixed elastohydrodynamic lubrication regime in which surface asperity contact occurs simultaneously during the lubrication process. Predicting performance (i.e., pressure, temperature) of components operating in this regime is important as the high asperity contact pressures can significantly reduce the fatigue life of the interacting components. In this study, a deterministic mixed lubrication model was developed to determine the pressure and temperature of mixed lubricated circular and elliptic contacts for measured and simulated surfaces operating under pure rolling and rolling/sliding condition. In this model, we simultaneously solve for lubricant and asperity contact pressures. The model allows investigation of the condition and transition from boundary to full-film lubrication. The variation of contact area and load ratios is examined for various velocities and slide-to-roll ratios. The mixed lubricated model is also used to predict the transient flash temperatures occurring in contacts due to asperity contact interactions and friction. In order to significantly reduce the computational efforts associated with surface deformation and temperature calculation, the fast Fourier transform algorithm is implemented.

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

Analytical and Low-Order Numerical Modeling of Ball-to-Ball Contact Friction in Linear Ball Bearings and Ball Screws

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Bo Lin ◽  
Molong Duan ◽  
Chinedum E. Okwudire
Keyword(s):  
Case Studies ◽  
Numerical Models ◽  
Experimental Studies ◽  
Point Contact ◽  
Ball Screw ◽  
Contact Friction ◽  
Ball Bearings ◽  
Friction Behavior ◽  
Ball Contact ◽  
Low Order

Analytical and low-order numerical models are very useful for studying friction behavior of rolling element machine components like ball bearings and ball screws. This is because they provide generalizable insights into friction behavior at much lower computational costs compared with high-order numerical models like finite element analysis (FEA). While analytical and low-order numerical models in the literature are mainly focused on ball-to-groove contact friction, experimental studies have shown that ball-to-ball contact friction is also very important. This is especially true for linear ball bearings/guideways and ball screws which, unlike rotary ball bearings, do not typically make use of caged balls to prevent ball-to-ball contact. Therefore, in this paper, low-order numerical models for ball-to-ball contact friction in linear ball bearings and ball screws are developed. Furthermore, an analytical model for ball-to-ball contact friction in four-point contact linear ball bearing is derived by making simplifications to its low-order numerical model. Compared with ball-to-ball friction predictions from FEA models developed in ansys, the proposed numerical models are shown in case studies to be accurate within 7%, while computing at least three orders of magnitude faster. Moreover, case studies are used to demonstrate how the developed models can be used in practice, e.g., for the mitigation of ball-to-ball contact friction in linear ball bearings and the prediction of friction variation during the operation of a ball screw.

An Improved Analytical Model of Friction and Ball Motion in Linear Ball Bearings With Application to Ball-to-Ball Contact Prediction

2018 ◽  
Author(s):  
Bo Lin ◽  
Molong Duan ◽  
Chinedum E. Okwudire ◽  
Jason S. Wou
Keyword(s):  
Analytical Model ◽  
Analytical Formula ◽  
Point Contact ◽  
Friction Model ◽  
Linear Velocity ◽  
Contact Forces ◽  
Ball Bearings ◽  
Friction Behavior ◽  
Rolling Ball ◽  
Ball Contact

The friction behavior of rolling ball machine components like linear ball bearings is very important to their functionality. For instance, differences in linear velocity of balls induces ball-to-ball contact in certain circumstances, resulting in significant increases and variations in friction. In this paper, an improved analytical formula for determining the linear velocity of balls in four-point-contact linear ball bearings is derived as a function of contact angle deviations and contact forces. The analytical formula is validated against a comprehensive friction model in the literature and shown to be in good agreement, while an oversimplified analytical model proposed by the authors in prior work is shown to be inaccurate. A case study is presented where insights gained from the derived analytical formula are used to mitigate velocity difference of balls in a linear ball bearing which otherwise would experience ball-to-ball contact.

A Theory of Mixed Lubrication

1972 ◽  
Vol 186 (1) ◽  
pp. 421-430 ◽  
Author(s):  
H. Christensen
Keyword(s):  
Hydrodynamic Lubrication ◽  
Dynamic Properties ◽  
Mixed Lubrication ◽  
Rapid Rise ◽  
Operating Characteristics ◽  
Lubrication Regime ◽  
Lubricated Contact ◽  
Mixed Lubrication Regime ◽  
Lubrication Conditions ◽  
Lubrication Properties

The phenomena observed when a lubricated contact or bearing is operating under mixed lubrication conditions are assumed to arise from an interaction of the surface asperities or roughness as well as from hydro-dynamic action of the sliding surfaces. It is shown how one of the previously published stochastic models of hydrodynamic lubrication can be extended or generalized to deal with mixed lubricating conditions. As an illustration of the application of the theory to a concrete example the influence on the operating characteristics of a plane pad, no side-leakage bearing is analysed. It is found that in the mixed lubrication regime friction is mainly controlled by the boundary lubrication properties of the liquid–solid interface. Load, on the other hand, is almost entirely controlled by the hydro-dynamic properties of the bearing. It is demonstrated how transition to mixed lubrication conditions will cause a rapid rise in friction thereby producing a minimum point in the Stribeck type diagram.

scholarly journals Theoretical and Experimental Investigations on Transient Run-Up Procedures of Journal Bearings Including Mixed Friction Conditions

Lubricants ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 105 ◽  
Author(s):  
Maximilian Prölß ◽  
Hubert Schwarze ◽  
Thomas Hagemann ◽  
Philipp Zemella ◽  
Philipp Winking
Keyword(s):  
Experimental Data ◽  
Energy Equation ◽  
Hydrodynamic Lubrication ◽  
Frictional Coefficient ◽  
Journal Bearings ◽  
Numerical Code ◽  
Experimental Investigations ◽  
Lubrication Regime ◽  
Mixed Friction ◽  
Run Up

This paper focuses on the operating behavior of journal bearings for industrial machinery application during run-ups. For this purpose, a numerical simulation code that is based on a two-dimensional extended and generalized Reynolds equation and a full three-dimensional energy equation, was advanced by a theoretical model considering the effects of mixed friction and warming of journal components during start-up. The mixed friction routine contained the elastic half-spaces model proposed by Boussinesq, which considers the influence of rough surfaces by implementing flow factors and calculates additional stiffness and dissipation in areas with solid interactions. Furthermore, a transient term was added in the energy equation to consider the thermal inertia of journal, and bearing to ensure a realistic heating during run-ups. Results of the prediction were compared to experimental data taken from a special test rig built up for validation procedures. Besides the conventional sensors for temperature, oil flow, and relative motion between shaft and stator, a contact voltage measurement was installed to determine the intensity of mixed friction. The evaluation of experimental data by Stribeck curves, based on a shaft torsion measurement, indicated a significant influence of run-up time on frictional moment. The friction coefficient of the rotor bearing system was strongly influenced by the run-up time. A short run-up time reduced the frictional coefficient in the mixed lubrication regime while the opposite behavior was observed in the hydrodynamic lubrication regime. The numerical code predicted these tendencies in good agreement with experimental data, however, only if the transient energy model was applied.

Modelling Acoustic Emissions induced by dynamic fluid-asperity shearing in hydrodynamic lubrication regime

2021 ◽  
Vol 153 ◽  
pp. 106590 ◽  
Author(s):  
Jiaojiao Ma ◽  
Hao Zhang ◽  
Zhanqun Shi ◽  
Fulei Chu ◽  
Fengshou Gu ◽  
...  
Keyword(s):  
Hydrodynamic Lubrication ◽  
Acoustic Emissions ◽  
Lubrication Regime

Full Film Lubrication of Strip Rolling

1994 ◽  
Vol 116 (3) ◽  
pp. 569-576 ◽  
Author(s):  
Chung-Yeh Sa ◽  
William R. D. Wilson
Keyword(s):  
Hydrodynamic Lubrication ◽  
Thermal Analyses ◽  
Speed Ratio ◽  
Process Variables ◽  
Strip Rolling ◽  
Polyphenyl Ether ◽  
Roll Torque ◽  
Global Condition ◽  
Roll Separating Force ◽  
Film Lubrication

A mathematical model for liquid lubricated strip rolling in the full-film regime is developed. The model combines slab plasticity, hydrodynamic lubrication and thermal analyses to relate local and global condition to process variables and material properties. The predictions of the model are compared with experimental measurements of outlet speed ratio, roll separating force and roll torque in rolling 1100-H14 aluminum with a viscous mineral oil and 5P4E polyphenyl ether as lubricants. The excellent agreement which is obtained provides powerful support of the validity of the model.

Development of performance indicators for Water-energy-food security and its application in Latin America and the Caribbean

2020 ◽  
Author(s):  
Jürgen Mahlknecht ◽  
Ramon Gonzalez ◽  
Frank Loge
Keyword(s):  
Latin America ◽  
Food Security ◽  
Green Infrastructure ◽  
Renewable Energy Sources ◽  
Green Economy ◽  
Electricity Production ◽  
Country Level ◽  
Research Areas ◽  
The Caribbean ◽  
Key Indicators

<p>Understanding water-energy-food interrelatedness and interdependencies (WEF Nexus) over environmental resources can result in improved water, energy, and food security by integrating management and governance across sectors and scales, reducing tradeoffs, and building synergies, overall promoting sustainability and a transition to green economy. One of the most relevant research areas on the Nexus is the development of indexes to assess the performance of the three sectors and their interlinkages. These tools are essential to understanding the Nexus concept and to determine areas for improvement, especially in developing countries. To evaluate the WEF Nexus for a developing region, namely Latin America and the Caribbean (LAC), two approaches are proposed to evaluate water, energy and food security at intra-country level. First, a composite diagram was developed for LAC countries and subregions that considers three key indicators per sector: availability, access, and sustainability of the sector’s resources. Second, an analysis was performed for selected countries using internal factors that represent the most important interrelationships that exist within the WEF Nexus. The results show that access to food in LAC is relatively low in comparison to other developing regions. Regarding renewable energy sources, with the exception of some countries, the region’s share (including hydroelectricity) in electricity production is low. Water resources represent the most vulnerable sector for food and energy development of the countries (water for food, and water for energy), as well as the need to implement green infrastructure for sustainable water production (food for water).</p>

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