An Average Lubrication Equation for Thin Film Grain Flow With Surface Roughness Effects

Tsai, Hung Jung; Jeng, Yeau-Ren

doi:10.1115/1.1484113

Cited by 18 publications

(15 citation statements)

References 12 publications

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“…Furthermore, McKeague and Khonsari 17 studied the behaviour of powder lubricated slider bearings with general boundary conditions that takes into account the powder slippage. Tsai and Jeng 18 derived a closed-form average lubrication equation for thin film grain flow with the effects of surface roughness. The authors have utilized the grain theory proposed by Haff 14 in their derivation.…”

Section: Several Modelling Techniques Have Been Developedmentioning

confidence: 99%

Stability of rotor supported on powder lubricated journal bearings with surface pockets

Rahmani

Dutt

Pandey

2020

Proceedings of the Institution of Mechanical Engineers, Part C:

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Conventional oil lubricated journal bearings experience a degradation in the lubrication properties of oil at high temperatures thereby making the use of oil lubricants impractical in a hot working environment. Under these conditions, powder lubricants can be used for the successful operation of the rotor-bearing system. Whirl instability is a serious problem for rotors supported on journal bearings which restrict the system to be operated at high speeds. Surface modifications in the form pocket in the bearing can be used to improve the performance. A sudden change in film thickness caused by the presence of pocket in the bearing will generate hydrodynamic pressure which will support the external load and may influence the stability of the rotor supported on such bearings. The objective of this paper is to explore the stability characteristics of powder lubricated journal bearings employing pockets of different shapes (rectangular, trapezoidal, elliptical, and parabolic). It is observed that though the pocket of all shapes increases the whirl stability of a rotor-shaft system, the rectangular shape is the most effective among all. Therefore, such bearings may be given a rectangular pocket to increase the stability of rotors.

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Section: Several Modelling Techniques Have Been Developedmentioning

confidence: 99%

Stability of rotor supported on powder lubricated journal bearings with surface pockets

Rahmani

Dutt

Pandey

2020

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…14 The characteristics of journal bearing lubricated with granular particles were studied by Tsai and Jeng. 15,16…”

Section: Introductionmentioning

confidence: 99%

“…14 The characteristics of journal bearing lubricated with granular particles were studied by Tsai and Jeng. 15,16 The flow behavior of powder lubricants was studied by Zhou and Khonsari 17 by developing a mathematical model. 18 They studied the lubrication mechanism occurring between two parallel plates.…”

Section: Introductionmentioning

confidence: 99%

Static and dynamic performance characteristics of powder lubricated symmetrical three-lobed bearing

Jose

Behera

2020

Proceedings of the Institution of Mechanical Engineers, Part J:

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Hydrodynamic oil bearings applied at elevated temperatures and extreme operating conditions are subjected to the problem of oil degradation. In order to overcome such conditions, dry powder lubricants are used as lubricants in the hydrodynamic journal bearings. Thus the problem of thermal degradation of oil at high temperatures can be eliminated. In this work, the static and dynamic characteristics of a symmetric three-lobed bearing lubricated with powdered particles have been predicted. Influence of the ellipticity ratio on the performance of the three-lobed bearing has also been investigated. It is observed that an increase in the ellipticity ratio increases the coefficient of friction and stability, but decreases the side leakage and the load carrying capacity of the three-lobed bearing. Also, it was observed that the large-sized powdered particles induce better load carrying capacity and better stability than the small-sized particles.

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“…The flow factor tensor, derived by the Green function technique and using the perturbation approach, has been the most complete description of the interaction between lubricant flow and roughness. The flow factors method has been applied to grain flow lubrication [28,29].…”

Section: Introductionmentioning

confidence: 99%

“…The wafer and pad are considered to be equal in width. Based on order-of-magnitude analysis, Haff's grain flow theory and using the Patir/Cheng flow factors by Tripp's perturbation approach, the generalized average lubrication equation is obtained as[28] …”

mentioning

confidence: 99%

An improved model considering elastic—plastic contact and partial hydrodynamic lubrication for chemical mechanical polishing

Tsai

Jeng

Huang

2008

Proceedings of the Institution of Mechanical Engineers, Part J:

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Chemical mechanical polishing (CMP) has become a primary technique for planarization of semiconductor wafers in sub-micro device fabrication. A physical CMP model combines the effects of grain flow hydrodynamic lubrication, pad roughness, and asperity contact between wafer and pad. In this study, an improved CMP model, considering both the grain flow with roughness effects and the micro-contact mechanism, is proposed. The model applies the average lubrication equation with partial hydrodynamic lubrication theory and considers the elastic-plastic micro-contact theory. The applied load acting on the wafer is balanced by the slurry pressure in the non-contact area, and the surface asperity contact force in the contact area. The effects of the CMP parameters including applied load, rotation speed, particle size, and pad roughness are studied and discussed. The simulation results compare well with experimental data in the literature and contribute to further understanding in wafer-pad contact mechanism.

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An Average Lubrication Equation for Thin Film Grain Flow With Surface Roughness Effects

Cited by 18 publications

References 12 publications

Stability of rotor supported on powder lubricated journal bearings with surface pockets

Stability of rotor supported on powder lubricated journal bearings with surface pockets

Static and dynamic performance characteristics of powder lubricated symmetrical three-lobed bearing

An improved model considering elastic—plastic contact and partial hydrodynamic lubrication for chemical mechanical polishing

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