Tribological performance of positive deterministic textured surfaces in parallel sliding lubricated contacts: Effect of texture size and height

2020 ◽  
Vol 234 (12) ◽  
pp. 1908-1925
Author(s):  
Dillip K Panigrahi ◽  
Mihir Sarangi
Keyword(s):  
Cross Sections ◽  
Thrust Bearing ◽  
Tribological Performance ◽  
Hydrodynamic Performance ◽  
Frictional Torque ◽  
Textured Surfaces ◽  
Lubricated Contacts ◽  
Large Size ◽  
Load Carrying ◽  
Texture Size

Recent studies in tribology show that deterministic surface texture enhances the tribological performance of parallel sliding lubricated contacts in terms of reduction in friction and an increase in load carrying capacity. This paper presents an experimental study to assess the effect of texture size and height on hydrodynamic performance of parallel sliding thrust bearing. Positive deterministic textures of different size and height with circular, elliptical, square and triangular cross-sections are fabricated for investigation. The experiments are performed using an in-house developed thrust bearing apparatus with constant flow lubrication system. The most important finding is that all the textured surfaces produce lower frictional torque and higher bearing clearance as compared to the untextured surface under varying load and speed. From the test results, it is found that with same texture height, specimens having small texture size perform better tribological characteristics followed by medium and large size textures. Furthermore, it is reported that with same texture size, a higher value of texture height is promising better hydrodynamic performance for all shapes.

On the Influence of Finite Wall Conductance and Inertia Effects of Hydrostatic Thrust Bearing

1978 ◽  
Vol 100 (2) ◽  
pp. 271-278
Author(s):  
V. K. Kapur ◽  
Kamlesh Verma
Keyword(s):  
Analytical Study ◽  
Thrust Bearing ◽  
Necessary Conditions ◽  
Axial Magnetic Field ◽  
Constant Angular Velocity ◽  
Frictional Torque ◽  
Load Carrying Capacity ◽  
Inertia Effects ◽  
Parallel Disks ◽  
Load Carrying

An analytical study is presented on the influence of finite wall conductance and inertia effects in magnetohydrodynamic lubrication flow between two parallel disks, one of which is rotating with constant angular velocity, in the presence of the axial magnetic field. Numerical results showing the behavior of wall conductance and inertia effects on pressure distribution, load carrying capacity, critical speed, and frictional torque of the bearing are obtained. Results obtained will provide necessary conditions for wall materials to improve the bearing performance.

Performance investigation of micro-pocketed textured pad thrust bearing

2018 ◽  
Vol 70 (8) ◽  
pp. 1388-1395 ◽  
Author(s):  
Shipra Aggarwal ◽  
R.K. Pandey
Keyword(s):  
Coefficient Of Friction ◽  
Cross Sections ◽  
Carrying Capacity ◽  
Thrust Bearing ◽  
Load Carrying Capacity ◽  
Temperature Relation ◽  
Cross Sectional ◽  
Content Type ◽  
Load Carrying ◽  
Coupled Solution

Purpose The purpose of this paper is to conceive a new surface texture incorporating a tiny shape among the micro-pockets (with circular, rectangular, trapezoidal and triangular cross-sections) and dimples (cylindrical, hemispherical and ellipsoidal) for exploring to enhance the maximum possible performance behaviors of sector shape pad thrust bearing. Design/methodology/approach Numerical simulation of hydrodynamically lubricated sector shape textured pad thrust bearing has been presented incorporating thermal and cavitation effects. The coupled solution of governing equations (Reynolds equation, film thickness expression, viscosity–temperature relation, energy equation and Laplace equation) has been achieved using finite difference method and Gauss–Seidel iterative scheme. Findings With new textured pads, higher load-carrying capacity and lower coefficient of friction are obtained in comparison to plain sector shape pad. Texture pattern comprising square cross-sectional pockets yields higher load-carrying capacity and lower coefficient of friction in comparison to other cross-sectional shapes (circular, trapezoidal and triangular) of pockets considered herein. Originality/value This study reports a new texture, which involves micro-pockets of square cross-sectional shapes to improve the performance behavior of sector shape pad thrust bearing. About 75 per cent increase in load carrying capacity and 42 per cent reduction in coefficient of friction have been achieved with pad having new texture in comparison to conventional pad.

scholarly journals Appearance of Hysteresis Phenomena on Hydrodynamic Lubrication in a Seal-Type Thrust Bearing with Dimples

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5222
Author(s):  
Reo Miwa ◽  
Norifumi Miyanaga ◽  
Jun Tomioka
Keyword(s):  
Carrying Capacity ◽  
Thrust Bearing ◽  
Hydrodynamic Lubrication ◽  
Frictional Torque ◽  
Hysteresis Phenomenon ◽  
Load Carrying Capacity ◽  
Cavitation Bubbles ◽  
Load Carrying ◽  
The Difference ◽  
Hysteresis Phenomena

This paper described unique hysteresis phenomena that appear in the hydrodynamic lubrication properties of dimpled thrust bearings. A seal-type thrust bearing specimen was textured with dimples. The load-carrying capacity and frictional torque were measured with a constant film thickness and compared to those of a dimple-free specimen. For examining the size of cavitation bubbles that occurred in various conditions, the lubricating area was observed during experiments. The used dimpled specimen produced the load-carrying capacity, and it exhibited an interesting hysteresis phenomenon, the difference in the values in the increasing and decreasing processes of rotational speed. The visualization test results revealed that the size of cavitation bubbles occurring within the dimples strongly affected this phenomenon. In addition, the dimpled specimen was able to reduce the frictional torque compared to the dimple-free specimen. However, the frictional torque did not show the hysteresis loop similar to that shown in the load-carrying capacity.

Influence of micro-groove attributes on frictional power loss and load-carrying capacity of hybrid thrust bearing

2019 ◽  
Vol 72 (5) ◽  
pp. 589-598 ◽  
Author(s):  
Vivek Kumar ◽  
Satish C. Sharma ◽  
Kuldeep Narwat
Keyword(s):  
Reynolds Equation ◽  
Thrust Bearing ◽  
Surface Texturing ◽  
Fluid Film ◽  
Element Formulation ◽  
Textured Surfaces ◽  
Content Type ◽  
Cavitation Phenomenon ◽  
Fluid Film Bearings ◽  
Load Carrying

Purpose Micro-surface texturing is emerging as a possible way to enhance the tribological performance of hydrodynamic fluid film bearings. In view of this, numerical simulations are carried out to examine the influence of surface texture on performance of hybrid thrust bearing system. This paper aims to determine optimum attributes of micro-grooves for thrust bearing operating in hybrid mode. Design/methodology/approach An iterative source code based on finite element formulation of Reynolds equation has been developed to numerically simulate flow of lubricant through the bearing. Mass-conserving algorithm based on Jakobsson–Floberg–Olsson (JFO) condition has been used to numerically capture cavitation phenomenon in the bearing. Gauss Siedel method has been used to obtain steady state performance parameters of the bearings. Findings A parametric study has been performed to improve the load supporting capacity of the bearing by optimizing micro-groove attributes and configuration. It is noticed that use of full-section micro-groove is beneficial in improving the efficiency of bearing by enhancing the fluid film reaction and reducing the film frictional power losses. Originality/value This study is helpful in examining the usefulness of micro-groove textured surfaces in hybrid thrust bearing applications.

The Influence of Surface Patterning on the Thermal Properties of Textured Thrust Bearings

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Gen Fu ◽  
Alexandrina Untaroiu
Keyword(s):  
Surrogate Model ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Three Dimensional ◽  
Major Axis ◽  
Friction Torque ◽  
Design Parameters ◽  
Textured Surfaces ◽  
Lubricated Contacts ◽  
Radial Extent

Contact performance can be enhanced by using textured surfaces. These are also found to have influences on lubricated contacts. A procedure to find the optimal partially textured thrust bearing configuration is presented in this study. A parallel sector-pad thrust bearing is simulated by a three-dimensional (3D) computational fluid dynamics (CFD) model. The stationary surface of the bearing is textured with dimples, while the rotor surface is flat. The results of the baseline model are validated by experimental data. In this study, we compare rectangular and elliptical dimples by investigating design parameters, such as major the length of the major axis (width), the length of the minor axis (length), dimple depth, circumferential space between two dimples, radial space between two dimples, radial extent, circumferential extent are selected as design parameters. A parametric study is conducted to investigate the influence of the texture geometries and a surrogate model is created. Based on the surrogate model, a multi-objective optimization scheme is used to navigate the design space and find the optimal texture structure that provides a lower maximal temperature inside the fluid film, higher load capacity, and lower friction torque. The results show that the optimal radial extent of the texture is around 80% of the pad radial length for both cases. The optimal length of the elliptical dimples in the circumferential direction is about 30% larger than the value of the rectangular dimples. In the final optimal design, the maximal temperature reduces 1.1% and 1.3% for rectangular and elliptical dimples while the load capacities are maintained at the same level.

Fabrication of Deterministic Micro-Asperities on Thrust Surfaces Using Photo Chemical Machining

2019 ◽  
Author(s):  
Dillip Kumar Panigrahi ◽  
Mihir Sarangi
Keyword(s):  
Mild Steel ◽  
Hydrodynamic Lubrication ◽  
Cost Effective ◽  
Operating Conditions ◽  
Hydrodynamic Performance ◽  
Photographic Emulsion ◽  
Frictional Torque ◽  
Bottom Surface ◽  
Textured Surfaces ◽  
Thrust Pad

Abstract The present invention relates to characterization and the sequence of operations in photo chemical machining as a means to fabricate positive deterministic micro-textures on mild steel thrust pad surfaces. Fabrication of surface micro-texture by current technique is conceived in two-stages: where photographic emulsion process is used to pattern the microstructure, and chemical etching method is employed to fabricate the textures on mild steel surface by dissolving exposed metal surface. The texture fabricated by present invention is having slightly rough etched bottom surface with sharp edge and least amount of burrs around the texture rim and the process is also cost effective. Several aspects regarding sequence of operations in manufacturing process and the characterization of fabricated textured surfaces are discussed. The physical significance of micro-asperities on hydrodynamic lubrication is presented experimentally under constant flow system. The variation of hydrodynamic performance parameters such as frictional torque, fluid film thickness and recess pressure with different operating conditions such as varying speed and supply pressure are outlined.

scholarly journals Fast laser surface texturing of spherical samples to improve the frictional performance of elasto-hydrodynamic lubricated contacts

Friction ◽  
2021 ◽  
Author(s):  
G. Boidi ◽  
P. G. Grützmacher ◽  
A. Kadiric ◽  
F. J. Profito ◽  
I. F. Machado ◽  
...  
Keyword(s):  
Surface Texturing ◽  
Hydrodynamic Pressure ◽  
Friction Reduction ◽  
Laser Surface Texturing ◽  
Textured Surfaces ◽  
Engineering Applications ◽  
Lubricated Contacts ◽  
Fluid Uptake ◽  
Direct Laser ◽  
Frictional Performance

AbstractTextured surfaces offer the potential to promote friction and wear reduction by increasing the hydrodynamic pressure, fluid uptake, or acting as oil or debris reservoirs. However, texturing techniques often require additional manufacturing steps and costs, thus frequently being not economically feasible for real engineering applications. This experimental study aims at applying a fast laser texturing technique on curved surfaces for obtaining superior tribological performances. A femtosecond pulsed laser (Ti:Sapphire) and direct laser interference patterning (with a solid-state Nd:YAG laser) were used for manufacturing dimple and groove patterns on curved steel surfaces (ball samples). Tribological tests were carried out under elasto-hydrodynamic lubricated contact conditions varying slide-roll ratio using a ball-on-disk configuration. Furthermore, a specific interferometry technique for rough surfaces was used to measure the film thickness of smooth and textured surfaces. Smooth steel samples were used to obtain data for the reference surface. The results showed that dimples promoted friction reduction (up to 20%) compared to the reference smooth specimens, whereas grooves generally caused less beneficial or detrimental effects. In addition, dimples promoted the formation of full film lubrication conditions at lower speeds. This study demonstrates how fast texturing techniques could potentially be used for improving the tribological performance of bearings as well as other mechanical components utilised in several engineering applications.

scholarly journals Two-scale homogenization of hydrodynamic lubrication in a mechanical seal with isotropic roughness based on the Elrod cavitation algorithm

2021 ◽  
pp. 135065012110176
Author(s):  
Yanxiang Han ◽  
Qingen Meng ◽  
Gregory de Boer
Keyword(s):  
Surface Topography ◽  
Carrying Capacity ◽  
Hydrodynamic Lubrication ◽  
Tribological Performance ◽  
Stribeck Curve ◽  
Polar Coordinate System ◽  
Load Carrying Capacity ◽  
Mechanical Seal ◽  
Macro Scale ◽  
Load Carrying

A two-scale homogenization method for modelling the hydrodynamic lubrication of mechanical seals with isotropic roughness was developed and presented the influence of surface topography coupled into the lubricating domain. A linearization approach was derived to link the effects of surface topography across disparate scales. Solutions were calculated in a polar coordinate system derived based on the Elrod cavitation algorithm and were determined using homogenization of periodic simulations describing the lubrication of a series of surface topographical features. Solutions obtained for the hydrodynamic lubrication regime showed that the two-scale homogenization approach agreed well with lubrication theory in the case without topography. Varying topography amplitude demonstrated that the presence of surface topography improved tribological performance for a mechanical seal in terms of increasing load-carrying capacity and reducing friction coefficient in the radial direction. A Stribeck curve analysis was conducted, which indicated that including surface topography led to an increase in load-carrying capacity and a reduction in friction. A study of macro-scale surface waviness showed that the micro-scale variations observed were smaller in magnitude but cannot be obtained without the two-scale method and cause significant changes in the tribological performance.

scholarly journals Eigenproblem Versus the Load-Carrying Capacity of Hybrid Thin-Walled Columns with Open Cross-Sections in the Elastic Range

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3468
Author(s):  
Zbigniew Kolakowski ◽  
Andrzej Teter
Keyword(s):  
Cross Sections ◽  
Carrying Capacity ◽  
Ultimate Load ◽  
Equilibrium Path ◽  
Load Carrying Capacity ◽  
Nonlinear Buckling ◽  
Elastic Range ◽  
Load Carrying ◽  
Thin Walled ◽  
Ultimate Load Carrying Capacity

The phenomena that occur during compression of hybrid thin-walled columns with open cross-sections in the elastic range are discussed. Nonlinear buckling problems were solved within Koiter’s approximation theory. A multimodal approach was assumed to investigate an effect of symmetrical and anti-symmetrical buckling modes on the ultimate load-carrying capacity. Detailed simulations were carried out for freely supported columns with a C-section and a top-hat type section of medium lengths. The columns under analysis were made of two layers of isotropic materials characterized by various mechanical properties. The results attained were verified with the finite element method (FEM). The boundary conditions applied in the FEM allowed us to confirm the eigensolutions obtained within Koiter’s theory with very high accuracy. Nonlinear solutions comply within these two approaches for low and medium overloads. To trace the correctness of the solutions, the Riks algorithm, which allows for investigating unsteady paths, was used in the FEM. The results for the ultimate load-carrying capacity obtained within the FEM are higher than those attained with Koiter’s approximation method, but the leap takes place on the identical equilibrium path as the one determined from Koiter’s theory.

On the Significance of the Inlet Pressure Build-Up in the Design of Tilting-Pad Bearings

1990 ◽  
Vol 112 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Cz. M. Rodkiewicz ◽  
K. W. Kim ◽  
J. S. Kennedy
Keyword(s):  
Thrust Bearing ◽  
Ambient Pressure ◽  
Inlet Pressure ◽  
Load Carrying Capacity ◽  
Integral Theorem ◽  
Lubricating Film ◽  
Tilting Pad ◽  
Load Carrying ◽  
Momentum Integral ◽  
Entrance Pressure

An operating tilting-pad thrust bearing generates a fore-region which is responsible for maintaining, at the bearing entrance, a pressure which is higher than the ambient pressure. This entrance pressure, in the presented analysis, is obtained by applying to the fore-region the momentum integral theorem. The solution of the lubricating film region is then obtained by using this modified inlet pressure. This solution yields the pressure distribution, the load carrying capacity, the film ratio and the frictional force for several values of the modified Reynolds number and various pivot positions. The analysis shows that there is a significant influence of the fore-region pressure on the bearing performance and that to properly design efficient tilting-pad bearing this effect should be taken into consideration.

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