Optimization of Partially Textured Parallel Thrust Bearings With Square-Shaped Micro-Dimples

Rahmani, Ramin; Shirvani, Ayoub; Shirvani, Hassan

doi:10.1115/ijtc2006-12167

Cited by 22 publications

(36 citation statements)

References 8 publications

(7 reference statements)

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“…In addition, since the trailing edge has always a negative effect on the textured bearing performance by producing negative pressures [25], by reducing the corresponding trailing edges for both negative and positive textures, one can reduce this negative effect. Figures 5a and b demonstrate the variations of dimensionless pressure distribution inside the lubricant film for two series of tests.…”

Section: The Optimisation Results and Discussionmentioning

confidence: 99%

“…Considering Figure 2 and the given surface profile for negative rectangular textures in equation (22) as well as employing the defined dimensionless geometrical parameters in equations (17) to (21), the following analytical dimensionless relations can be achieved for the load capacity, friction force and lubricant flow rate, respectively, ( ) (25) where Λ W , Λ F and Λ Q are:…”

Section: Figurementioning

confidence: 99%

“…1551-1565 (Accepted Version) analyses and thus, there is a lack of understanding of the nature of dependence of the interacting parameters with the desired tribological performance measures. In the present study, the previous model to study the textured surfaces with square form identical irregularities [25] is generalised and further developed to include the explicit analytical relations for various texture types and profiles and present the optimum results based on different performance measures. In this study, the Reynolds equation has been analytically solved for a generic textured contact profile and consequently the analytical relations for bearing performance parameters are obtained.…”

Section: Introductionmentioning

confidence: 99%

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An analytical approach for analysis and optimisation of slider bearings with infinite width parallel textures

Rahmani

Mirzaee

Shirvani

et al. 2010

Tribology International

120

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This paper introduces an analytical approach to study the textured surfaces in hydrodynamic lubrication regime. For this purpose, a method of integrating the Reynolds equation for slider bearings with surface discontinuities is presented. By introducing appropriate dimensionless parameters, analytical relations for various texture profiles in both indented and projected forms are delivered. These relations express the nature of mathematical dependence between textured bearing performance measures and geometrical/operational parameters. An optimisation procedure is employed to achieve the optimum texturing parameters promoting maximum load capacity, load capacity to lubricant flow rate ratio and minimum friction coefficient for asymmetric partially textured slider bearings. Keywords IntroductionIt is now widely accepted that introducing artificially created micro-features onto sliding surfaces can significantly affect friction and wear of the sliding bearings. It is further believed that the textured surfaces provide the best performance amongst all other mechanical surface treatments [1]. The positive effect of artificial surface texturing on enhancing the load capacity, wear resistance and/or friction coefficient of mechanical seals [2], piston-ring/cylinder liner mechanism in internal combustion engines [3,4,5] and roller/piston in hydraulic motors [6] as some of the application examples are shown through numerical and/or experimental studies.Considering the associated theoretical studies, in a pioneering work by Salama [7], the effect of macro-roughness induced by manufacturing process in the form of surface waviness on the slider bearing performances was studied. As a result, existence of an optimum waviness length to amplitude was reported. By developing a theoretical model to obtain pressure distribution for a single micro-asperity and then, spreading the results for a population of asperities mounted on a radial face seal, Hamilton et al [8] notified existence of an optimum range for asperity height and asperity area fraction providing the maximum loads support. They suggested further research on the effect of interactions amongst asperities. On the other hand, an analytical/experimental study on microasperity lubrication by Anno et al [9] proposed that the poorer correlation between experimental and theoretical results in [8] could be improved by considering the hydrodynamic load support induced by small tilts on the tops of asperities. Later on, Anno et al [10] extended the study to 'negative asperities' and concluded that although all shape of asperities (whether positive or negative) of comparable dimension produce similar load support, to avoid leakage, one must utilise negative asperities.The study of tribological effects obtained by introducing surface microfeatures was brought to the centre of attention again by Etsion and Burstein [11] who focused on the study of the effect of shallow pores on the operational behaviour of the mechanical face seals. They solved the Reynolds equation numer...

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Section: The Optimisation Results and Discussionmentioning

confidence: 99%

Section: Figurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

An analytical approach for analysis and optimisation of slider bearings with infinite width parallel textures

Rahmani

Mirzaee

Shirvani

et al. 2010

Tribology International

120

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“…For surfaces with geometrical (profile) discontinuities such as those that comprise a number of regular textured patterns, an analytical approach has been introduced by Rahmani et al (2007). The method has been developed in Rahmani et al (2010) to include any given texture profile either in negative or positive form.…”

Section: Analytical Approachmentioning

confidence: 99%

Optimised textured surfaces with application in piston ring/cylinder liner contact

Rahmani

Shirvani

2010

Tribology and Dynamics of Engine and Powertrain

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This item was submitted to Loughborough's Institutional Repository (https://dspace.lboro.ac.uk/) by the author and is made available under the following Creative Commons Licence conditions.For the full text of this licence, please go to: http://creativecommons.org/licenses/by-nc-nd/2.5/ In: Tribology and Dynamics of Engine and Powertrain: Fundamentals, Applications and Future Trends, Edited by H. Rahnejat, Woodhead Publishing, 2010, pp. 470-517, ISBN: 978-1-84569-993-2 Chapter 14 Optimised Textured Surfaces with Application in Piston-Ring/Cylinder Liner Contact R. RAHMANI, Loughborough University, UK A. SHIRVANI and H. SHIRVANI, Anglia Ruskin University, UK Abstract: The application of textured surfaces in tribology has recently gained a huge momentum. In this chapter, a systematic approach to investigate the maximum outcomes from employing such surfaces is introduced with an insight into their application in internal combustion engines. A combination of various affecting parameters on the tribological performance of such surfaces is studied and the optimum results were introduced. The effect of employing such optimised textures in enhancing the lubrication condition in piston ring/cylinder liner contact is also studied.Key words: surface texturing, piston ring/cylinder liner contact, optimisation, slider bearings IntroductionIn general, friction is inherent to and is produced between bodies in contact with relative motion. Friction tends to oppose this relative motion between the bodies through loss of energy mostly in the form of heat, mechanical vibration and noise. Therefore, in most cases, friction is an unfavourable phenomenon. In some cases introduction of friction is desired, for example in order to slow down a moving car, the brakes are used to reduce the existing kinetic energy in the wheels by means of producing frictional losses. However, in most of the cases, facilitating this relative motion between bodies is of concern and as a result, one needs to overcome friction so that the relative motion pursues with a minimal loss of energy.Excessive friction can cause damage to the surfaces in contact in several ways and as a result make them wear. Since the surfaces are damaged due to wear, the rate of energy dissipation due to friction increases and consequently amplifies the rate of wear itself (see Chapter 2).The reason for the existence of friction is mainly that in reality, there is no perfect smooth surface. In fact, surfaces have a degree of roughness in the form of small 'hills' and 'valleys' no matter how well they are prepared. When two surfaces, which are in contact with each other, are put into relative motion, the asperities on the In: Tribology and Dynamics of Engine and Powertrain: Fundamentals, Applications and Future Trends, Edited by H. Rahnejat, Woodhead Publishing, 2010, pp. 470-517, ISBN: 978-1-84569-993-2 opposing surfaces become locked hence inducing friction as initially proposed by Amontons for onset of motion and later under kinetic conditions by Coulomb (see Chapter 2). W...

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“…A demonstration of the advantages of pad texturing regarding thrust bearing performance is included in Tonder [6] and Etsion et al [7]. New concepts related to sliders capable of operating in environments other than lubricating oils, under severe loading conditions corresponding to elasto-hydrodynamic operation, have been recently analyzed, mainly in terms of parametric computational studies [8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Thermohydrodynamic analysis of a textured sector-pad thrust bearing: effects on mechanical deformations

Charitopoulos

Fouflias

Papadopoulos

et al. 2014

Mechanics & Industry

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-In this paper, a computational investigation of thermohydrodynamic performance and mechanical deformations of a fixed-geometry thrust bearing with artificial surface texturing is presented. A parallel eight-pad bearing is considered; the surface of each pad is partially textured with square dimples. Here, a CFD-based thermohydrodynamic modeling approach, recently introduced by the authors, is used to calculate the performance of the bearing; the THD results are then used to quantify the deformations of the bearing mechanical parts. The bearing is modelled as a sector-shaped channel, consisting of a smooth rotating wall (thrust collar) and a partially textured stationary wall (bearing pad). The bearing performance characteristics are computed by means of numerical simulations, based on the numerical solution of the Navier-Stokes and energy equations for incompressible flow, as well as on the solution of the elasticity equations for the bearing solid parts. Here, a reference texture geometry is considered, while proper thermal and structural boundary conditions are implemented. For representative film thickness values, the effect of rotational speed and collar thickness on bearing performance is quantified, and the resulting pad and rotor deformation fields are computed. It is found that, due to oil heating, the load carrying capacity decreases with rotational speed for values higher that approximately 2000 rpm. The computed rotor deformation field is representative of a fixed support beam, characterized by substantially higher levels than those of the bearing pad. Rotor deformations increase substantially at low values of collar thickness.

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Optimization of Partially Textured Parallel Thrust Bearings With Square-Shaped Micro-Dimples

Cited by 22 publications

References 8 publications

An analytical approach for analysis and optimisation of slider bearings with infinite width parallel textures

An analytical approach for analysis and optimisation of slider bearings with infinite width parallel textures

Optimised textured surfaces with application in piston ring/cylinder liner contact

Thermohydrodynamic analysis of a textured sector-pad thrust bearing: effects on mechanical deformations

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