PURE SQUEEZE FILM BEHAVIOR OF LONG JOURNAL BEARINGS WITH COUPLE STRESS FLUIDS UNDER DYNAMIC LOADING

2000 ◽  
Vol 24 (3-4) ◽  
pp. 477-492 ◽  
Author(s):  
Jaw-Ren Lin ◽  
Yeon-Pun ◽  
Yuan Kang ◽  
Kuo-Chiang Cha
Keyword(s):  
Couple Stress ◽  
Reynolds Equation ◽  
Stokes Equations ◽  
Equations Of Motion ◽  
Journal Bearings ◽  
Squeeze Film ◽  
Eccentricity Ratio ◽  
Film Pressure ◽  
Couple Stresses ◽  
Bearing Life

On the basis of microcontinuum theory, a theoretical analysis of pure squeeze film behavior of journal bearings with couple stress lubricants operating under a dynamic load is presented. To account for the effects of couple stresses arising from the lubricant blended with various additives, the modified Reynolds equation governing the film pressure is obtained from Stokes equations of motion. Various bearing characteristics for long bearings are then calculated. According to the results obtained, the influence of couple stresses on the dynamic squeeze film motion is apparent and not negligible. Comparing with the Newtonian-lubricant case, the effects of coupe stresses provide and enhancement in the film pressure as well as a reduction in the velocity of the journal center; consequently, the maximum eccentricity ratio of the journal center is decreased. On the whole, the bearing lubricated with couple stress fluid signifies and improvement in the dynamic squeeze film performance and results in longer bearing life.

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.

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.

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.

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.

Linearized ph Stability Theory for Translatory Half-Speed Whirl of Long, Self-Acting Gas-Lubricated Journal Bearings

1963 ◽  
Vol 85 (4) ◽  
pp. 611-618 ◽  
Author(s):  
J. S. Ausman
Keyword(s):  
Stability Theory ◽  
Reynolds Equation ◽  
Equations Of Motion ◽  
Journal Bearings ◽  
Ph Stability ◽  
Time Dependent ◽  
Rotor Speed ◽  
Eccentricity Ratio ◽  
Bearing Sleeve ◽  
Threshold Point

The linearized ph approximation to the time dependent Reynolds equation is solved simultaneously with the equations of motion for a rotating journal shaft supported by a rigidly mounted bearing sleeve. Given the two bearing parameters Λ=6μωR2paC2 and Ω=MCω2πpaDL a critical operating eccentricity ratio is determined below which the bearing is unstable and above which the bearing is stable. Whirl frequency at the threshold point is computed to be equal to or slightly less than one-half rotor speed.

Numerical approach to interpret the attributes of porous journal bearings using couple-stress fluid

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Shalini M. Patil ◽  
C.V. Vinay ◽  
Dinesh P.A.
Keyword(s):  
Pressure Distribution ◽  
Peer Review ◽  
Couple Stress ◽  
Reynolds Equation ◽  
Multigrid Method ◽  
Stokes Equations ◽  
Weight Bearing ◽  
Journal Bearings ◽  
Couple Stress Fluid ◽  
Content Type

Purpose The purpose of this paper is to study the amalgamated consequences of nonNewtonian fluid and permeability for nonporous journal spinning with constant tangential velocity inside a rough porous bearing. Design/methodology/approach The flow is assumed to have developed under low Reynolds number, and the flow is governed by reduced Navier–Stokes equations. Based on Stokes theory for couple-stress fluid, a closed form of nonNewtonian Reynolds equation is obtained. Finite difference based multigrid method is adopted to study the various parameters of journal bearings. Findings It is found that bearing attributes such as pressure distribution and weight carrying capacity are commanding for nonNewtonian couple-stress fluid compared to the classical Newtonian case. Originality/value The multigrid method for the Reynolds equation is used, which accelerates the convergence rate of the solution and is independent of the grid size. The effects of couple-stress fluid promote the enhanced pressure distribution in the fluid. Both increased weight bearing capacity and delayed squeezing time reduce the skin-friction and hence take longer time to come in contact with each other. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2020-0051/

Effect of surface roughness on couple stress squeeze film lubrication of long porous partial journal bearings

2006 ◽  
Vol 58 (4) ◽  
pp. 176-186 ◽  
Author(s):  
N.M. Bujurke ◽  
N.B. Naduvinamani ◽  
Syeda Tasneem Fathima ◽  
S.S. Benchalli
Keyword(s):  
Surface Roughness ◽  
Couple Stress ◽  
Journal Bearings ◽  
Squeeze Film ◽  
Film Lubrication ◽  
Effect Of Surface

Inertial effect on gas squeeze film for large radius disc excited by standing waves with complex modal shapes

2019 ◽  
Vol 33 (24) ◽  
pp. 1950282 ◽  
Author(s):  
Yi Qiang Fan ◽  
M. Miyatake ◽  
S. Kawada ◽  
Bin Wei ◽  
S. Yoshimoto
Keyword(s):  
Reynolds Equation ◽  
Numerical Solutions ◽  
Stokes Equations ◽  
Standing Waves ◽  
Inertial Effect ◽  
Squeeze Film ◽  
Navier Stokes ◽  
Large Radius ◽  
Navier Stokes Equations ◽  
Sinusoidal Functions

In order to investigate the gas inertial effect on bearing capacity of acoustic levitation on condition of complex exciting shapes, a new kind of numerical model including inertial effect in cylindrical coordinates was proposed. The inertial terms in Navier–Stokes equations are packaged to derive modified Reynolds equations. The amplitudes of standing waves were tested by distance probe in experiment and film thickness equation were reconstructed by sum of the sinusoidal functions. The theoretical and experimental results implied that the inertial effect is strongly related to the exciting modal shapes. It is concluded that the proposal of modified Reynolds equation can provide more optimized numerical solutions to solve the problems about the deviation between theoretical and experimental data.

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