Derivation of non-Newtonian squeeze-film Reynolds equation between convex surfaces and application to two different cylinders

2007 ◽  
Vol 221 (7) ◽  
pp. 813-821 ◽  
Author(s):  
J-R Lin
Keyword(s):  
Couple Stress ◽  
Reynolds Equation ◽  
Continuum Theory ◽  
Type Equation ◽  
Squeeze Film ◽  
Convex Surfaces ◽  
Couple Stresses ◽  
Load Carrying ◽  
Film Characteristics ◽  
Couple Stress Fluids

The derivation of non-Newtonian squeeze-film Reynolds-type equation between two convex surfaces and its application are of interest in the present study. Based upon the Stokes micro-continuum theory, the non-Newtonian squeeze-film Reynolds-type equation between two convex surfaces is derived to take into account the effects of couple stresses resulting from the lubricant blended with various additives. This non-Newtonian squeeze-film Reynolds-type equation is applicable to squeeze-film bearings lubricated with couple stress fluids when the general upper film shape and the lower film shape are specified. To guide the use of the equation, the squeeze-film mechanism between two different cylinders of infinite width with non-Newtonian couple stress fluids is illustrated. Comparing with the Newtonian-lubricant case, the presence of non-Newtonian couple stresses provides an increase in the load-carrying capacity, and therefore lengthens the approaching time. In addition, the effects of couple stresses on the squeeze film characteristics are more pronounced at lower squeeze-film height with larger couple stress parameters and larger radius ratios of cylinders. As the value of radius ratio approaches infinity, the present results agree closely with those of the previous studies by Hamrock [6] and by Lin et al. [19], respectively; it provides a support to the present study.

Couple-stress squeeze films between porous rectangular plates

2003 ◽  
Vol 217 (3) ◽  
pp. 229-234 ◽  
Author(s):  
N. B. Naduvinamani ◽  
Syeda Tasneem Fathima ◽  
P. S. Hiremath
Keyword(s):  
Couple Stress ◽  
Reynolds Equation ◽  
Velocity Slip ◽  
Squeeze Film ◽  
Rectangular Plates ◽  
Couple Stresses ◽  
Load Carrying ◽  
Porous Interface ◽  
Couple Stress Fluids ◽  
Film Lubrication

In this paper, the squeeze-film lubrication theory between two isotropic porous rectangular plates has been advanced to analyse the effects of couple stresses arising due to the presence of microstructure additives in the lubricant, using the Stokes theory of couple-stress fluids. The most general form of the modified Reynolds equation is derived for the squeeze-film lubrication of the porous rectangular plates by taking into account of the velocity slip at the porous interface. An eigentype of expression is obtained for the squeeze-film pressure. The effects of the isotropic permeability, the couple stresses and the velocity slip parameters on the characteristics of the squeeze-film lubrication are discussed. A significant increase in the load-carrying capacity and the delayed squeeze-film time are observed for the couple-stress fluids in comparison with Newtonian fluids.

scholarly journals Effect of Surface Roughness and Viscosity-Pressure Dependency on the Couple Stress Squeeze Film Characteristics of Parallel Circular Plates

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Neminath Bhujappa Naduvinamani ◽  
Siddangouda Apparao ◽  
Ayyappa G. Hiremath
Keyword(s):  
Surface Roughness ◽  
Carrying Capacity ◽  
Couple Stress ◽  
Reynolds Equation ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Circular Plates ◽  
Pressure Dependency ◽  
Load Carrying ◽  
Film Characteristics

Combined effects of surface roughness and viscosity-pressure dependency on the couple stress squeeze film characteristics of parallel circular plates are presented. On the basis of Christensen’s stochastic theory, two types of one-dimensional roughness structures, namely, the radial roughness and azimuthal roughness patterns, are considered and the stochastic modified Reynolds equation for these two types of roughness patterns is derived for Stokes couple stress fluid by taking into account variation of viscosity with pressure. The standard perturbation technique is employed to solve the averaged Reynolds equation and closed form expressions for the mean fluid film pressure, load carrying capacity, and squeeze film time are obtained. It is found that the effects of couple stresses and viscosity-pressure dependency are to increase the load carrying capacity, and squeeze film time for both types of roughness patterns. The effect of azimuthal (radial) roughness pattern is to increase (decrease) these squeeze film characteristics as compared to the corresponding smooth case.

Static and dynamic behaviours of pure squeeze films in couple stress fluid-lubricated short journal bearings

1997 ◽  
Vol 211 (1) ◽  
pp. 29-36 ◽  
Author(s):  
J-R Lin
Keyword(s):  
Couple Stress ◽  
Cyclic Load ◽  
Reynolds Equation ◽  
Couple Stress Fluid ◽  
Squeeze Film ◽  
Film Pressure ◽  
Stress Effects ◽  
Bearing Life ◽  
Load Carrying ◽  
Film Characteristics

On the basis of microcontinuum theory, this paper theoretically investigates the rheological effects of couple stress fluids on the static and dynamic behaviours of pure squeeze films in journal-bearing systems. The general modified Reynolds equation with no journal rotation is derived by using the Stokes constitutive equations to account for the couple stress effects resulting from lubricants containing additives or suspended particles. The cases of short bearings under a constant applied load and an alternating load are analysed. The solutions for film pressure in a closed form are shown, from which the squeeze film characteristics are determined. According to the results evaluated, the effects of couple stresses significantly increase the film pressure and then the load-carrying capacity is compared with the Newtonian lubricant case. Under a cyclic load the couple stress effects provide a reduction in the velocity of the journal centre as well as an increase in the minimum permissible height of the squeeze film. As a consequence, the bearing with a couple stress fluid as the lubricant improves the squeeze film characteristics and results in a longer bearing life.

Investigation of squeeze film performance in rough parallel circular discs by ferro-fluid couple stress lubricant considering effects of rotational inertia

2018 ◽  
Vol 70 (7) ◽  
pp. 1201-1208 ◽  
Author(s):  
Maghsood Daliri
Keyword(s):  
Surface Roughness ◽  
Couple Stress ◽  
Couple Stress Theory ◽  
Squeeze Film ◽  
Rotational Inertia ◽  
Roughness Effects ◽  
Film Performance ◽  
Content Type ◽  
Couple Stresses ◽  
Film Characteristics

Purpose The purpose of this paper is to investigate squeezing and rotating motions between two rough parallel circular discs lubricated by ferro-fluid couple stress lubricant. Design/methodology/approach Based upon the Stokes couple stress theory, ferro-hydrodynamic model of Shliomis and Christensen rough surfaces model, squeeze-film characteristics between two rough parallel circular discs considering rotational inertia effects are obtained. Findings According to the results, it is found that the combined effects of couple stresses and ferro-fluid lubricants increases squeeze film performance with respect to the classical Newtonian lubricant. However, increasing the rotational inertia parameter reduces squeeze film characteristics. On the other hand, depending on the structure of surface roughness, the squeeze film characteristics can be increased or decreased. Furthermore, results show that the surface roughness with circular pattern increases squeeze film characteristics, while the surface roughness with radial pattern will decrease it. Originality/value This paper is relatively original and describes the squeeze film characteristics between two parallel circular discs with ferro- fluid, rotational inertia, couple stresses and surface roughness effects.

scholarly journals Non-Newtonian Effects on the Squeeze Film Characteristics between a Sphere and a Flat Plate: Rabinowitsch Model

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Udaya P. Singh ◽  
Ram S. Gupta
Keyword(s):  
Flat Plate ◽  
Carrying Capacity ◽  
Significant Variation ◽  
Reynolds Equation ◽  
Fluid Model ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Film Pressure ◽  
Load Carrying ◽  
Film Characteristics

The use of additives (polyisobutylene, ethylene-propylene, lithium hydroxy stearate, hydrophobic silica, etc.) changes lubricants’ rheology due to which they show pseudoplastic and dilatant nature, which can be modelled as cubic stress fluid model (Rabinowitsch fluid model). The present theoretical analysis investigates the effects of non-Newtonian pseudoplastic and dilatant lubricants on the squeezing characteristics of a sphere and a flat plate. The modified Reynolds equation has been derived and an asymptotic solution for film pressure is obtained. The results for the film pressure distribution, load carrying capacity, and squeezing time characteristics have been calculated for various values of pseudoplastic parameter and compared with the Newtonian results. These characteristics show a significant variation with the non-Newtonian pseudoplastic and dilatant behavior of the fluids.

Homotopy Analysis of Circular Plates Squeeze Film Bearings Lubricated with Couple Stress Fluids: Piezo-Viscous Model

2020 ◽  
Vol 8 (2) ◽  
pp. 95-102
Author(s):  
J.P. Tripathi ◽  
◽  
U.P. Singh ◽  
B.K. Singh ◽  
◽  
...  
Keyword(s):  
Couple Stress ◽  
Load Capacity ◽  
Closed Form Solution ◽  
Continuum Theory ◽  
Form Solution ◽  
Squeeze Film ◽  
Bearing Plate ◽  
Homotopy Analysis ◽  
Pressure Parameter ◽  
Couple Stress Fluids

The piezo-viscous effect is crucial in fluid flows under high-pressure applications such as fluid film lubrication, microfluidics, and geophysics. We have investigated the combined influences of piezo-viscous dependence and non-Newtonian couple stresses on the performance of circular plate squeeze film bearings using Stokes Micro-Continuum theory of couple stress fluids together with the exponential variation of viscosity with pressure. A closed-form solution for film pressure has been obtained using the homotopy analysis method. The numerical results for pressure and load capacity with different values of the viscosity-pressure parameter have been calculated and compared with iso-viscous couple stress and Newtonian lubricants. An enhanced pressure and load capacity are observed in the analysis. The response time for the bearing (plate approach time) has also been calculated and a significant increase is observed.

scholarly journals The Performance of Squeeze Film between Parallel Triangular Plates with a Ferro-Fluid Couple Stress Lubricant

2020 ◽  
Vol 2020 ◽  
pp. 1-8 ◽  
Author(s):  
Akbar Toloian ◽  
Maghsood Daliri ◽  
Nader Javani
Keyword(s):  
Magnetic Field ◽  
Carrying Capacity ◽  
Couple Stress ◽  
Volume Concentration ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Uniform External Magnetic Field ◽  
Film Characteristics ◽  
The Magnetic Field

The present study aims at investigating a couple stress ferrofluid lubricant effects on the performance of the squeezed film when a uniform external magnetic field is applied. For this purpose, Shliomis ferrohydrodynamic and couple stress fluid models are employed. The considered geometry is parallel triangular plates. The effects of couple stress, volume concentration, and Langevin parameters on squeeze film characteristics including time vs. height relationship and load-carrying capacity are investigated. According to the results, employing couple stress ferrofluid lubricant in the presence of the magnetic field leads to an increased performance of the squeeze film.

Elastohydrodynamic Analysis of an Offset Journal Bearing Lubricated with Couple Stress Fluid

2010 ◽  
Vol 2 ◽  
pp. 53-62
Author(s):  
B. Chetti
Keyword(s):  
Elastic Deformation ◽  
Couple Stress ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Load Carrying Capacity ◽  
Static Characteristics ◽  
Large Molecules ◽  
Couple Stresses ◽  
Load Carrying

This work is an investigation of the performance characteristics of an offset journal bearing lubricated with a fluid with couple stresses taking into consideration the elastic deformation of the liner. The couple stresses might be expected to appear in noticeable magnitudes in liquids containing additives with large molecules. The modified Reynolds equation has been solved using the finite difference method. Load carrying capacity, attitude angle, side leakage and friction coefficients are determined for various values of couple stress parameter of a rigid and deformable bearing. It is found that, the static characteristics of journal bearings lubricated with couple stress fluids are improved compared to journal bearings lubricated with Newtonian fluids. It is concluded that, the elastic deformation of the bearing has significant influence on the bearing characteristics.

Combined effects of piezo – viscous coupled stress lubricant and rotational inertia upon squeeze film performance of rough circular discs

2015 ◽  
Vol 67 (6) ◽  
pp. 564-571 ◽  
Author(s):  
M. Daliri ◽  
D. Jalali-Vahid
Keyword(s):  
Surface Roughness ◽  
Couple Stress ◽  
Squeeze Film ◽  
Rotational Inertia ◽  
Combined Effects ◽  
Film Performance ◽  
Content Type ◽  
Couple Stresses ◽  
Pressure Dependency ◽  
Film Characteristics

Purpose – The purpose of this paper is to investigate squeezing and rotating motions between two rough parallel circular discs lubricated by piezo – viscous couple stress lubricant with pressure-dependent viscosity variation. Design/methodology/approach – Based upon the Stokes couple stress theory, Barus viscosity-pressure dependency relation and Christensen rough surfaces model, squeeze film characteristics between two rough parallel circular discs are obtained. Findings – According to the results, it is found that, the combined effects of couple stresses and viscosity-pressure dependency increases squeeze film performance with respect to the classical Newtonian iso-viscous (constant viscosity) lubricant. However, increasing the rotational inertia parameter reduces squeeze film characteristics. On the other hand, depending on the structure of surface roughness, the squeeze film characteristics can be increased or decreased. Furthermore, results show that the surface roughness with circular pattern increases squeeze film characteristics, while the surface roughness with radial pattern will decrease it. Originality/value – This paper is relatively original and describes the squeeze film characteristics between two parallel circular discs with viscosity-pressure dependency, rotational inertia, couple stresses and surface roughness effects.

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