scholarly journals Discussion: “Failure of Thin Film Lubrication—The Effect of Running-In on the Load Carrying Capacity of Thin-Film Lubricated Concentrated Contacts” (Begelinger, A., and de Gee, A. W. J., 1981, ASME J. Lubr. Technol., 103, pp. 203–208)

1981 ◽  
Vol 103 (2) ◽  
pp. 209-209
Author(s):  
A. Beerbower
Keyword(s):  
Thin Film ◽  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
Thin Film Lubrication ◽  
Load Carrying ◽  
Film Lubrication

Performance of Rotating Rough Circular Step Bearing: Characteristic of Lubrication at Nano Scale

2012 ◽  
Author(s):  
G. M. Deheri ◽  
P. R. Dave ◽  
Patel Himanshu Chimanlal
Keyword(s):  
Thin Film ◽  
Magnetic Fluid ◽  
Carrying Capacity ◽  
Couple Stress ◽  
Load Carrying Capacity ◽  
Thin Film Lubrication ◽  
Nano Scale ◽  
Load Carrying ◽  
Transverse Roughness ◽  
Film Lubrication

An endeavor has been made to investigate the effect of transverse surface roughness on the behaviour of thin film lubrication at nano scale of a magnetic fluid based rough porous rotating circular step bearing. Mainly, the combination of the properties of the surfaces, the lubricant and viscosity of the lubricant are responsible for thin film lubrication between two rough surfaces in relative motion. The effects induced by the transverse roughness and the couple stress cannot be disregarded in the regime while the ordered molecules dominate the fluid field. The random roughness of the surfaces is characterized by a random variable with non zero mean, variance and skewness. The associated Reynolds’ equation is then stochastically averaged and solved with appropriate boundary conditions to obtain the pressure distribution, leading to the calculation of load carrying capacity. It is easily observed that basically, the magnetic fluid lubricant combined with the couple stress effect is responsible for the improved performance of the bearing system. It is clearly seen that the adverse effect of transverse roughness is relatively less when considered with thin film lubrication at nano scale. The increased load carrying capacity due to variance (-ve) gets further increased due to negatively skewed roughness which becomes more pronounced owing to thin film lubrication at the nano scale. It is seen that the existence of couple stress enhances the load carrying capacity. In addition, the characteristic length contributing to the couple stress increases load carrying capacity considerably. Even, size dependent effects are noticed in the lubrication with couple stress while the thinner the lubrication film the more obvious is the effect.

Failure of Thin Film Lubrication—An Expedient for the Characterization of Lubricants

1981 ◽  
Vol 103 (4) ◽  
pp. 497-501 ◽  
Author(s):  
B. J. Tabor
Keyword(s):  
Thin Film ◽  
Chemical Composition ◽  
Bulk Viscosity ◽  
Carrying Capacity ◽  
Empirical Relation ◽  
Load Carrying Capacity ◽  
Thin Film Lubrication ◽  
Load Carrying ◽  
Film Lubrication

A method has been developed to characterize lubricants, starting from the failure of thin film lubrication in sliding concentrated steel contacts. For a number of lubricants, differing in viscosity and chemical composition, the collapse of the partial EHD film is taken as a criterion of the lubrication behavior. The contribution of viscosity and chemical composition of lubricants to the load carrying capacity of the partial EHD film at a speed of 1 m/s (P1) can be separated. This is achieved by plotting the value P1 as a function of the logarithm of the bulk viscosity (η). The following linear empirical relation P1 = β log η + α is found to be valid within the viscosity range of 2–200 • 10−3 Pa.s. Lubricants with the same chemical composition have an equal value of α.

The Present State of Lubrication and Its Relation to Rheology

1968 ◽  
Vol 90 (3) ◽  
pp. 526-530 ◽  
Author(s):  
J. K. Appeldoorn
Keyword(s):  
Thin Film ◽  
Reynolds Equation ◽  
Mathematical Treatment ◽  
Load Carrying Capacity ◽  
Thin Film Lubrication ◽  
Load Carrying ◽  
Viscoelastic Effects ◽  
Viscoelastic Liquids ◽  
Film Lubrication ◽  
Made In

In thick-film lubrication, Reynolds’ equation is generally satisfactory. However, the assumptions made in deriving this equation cannot be justified for non-Newtonian, viscoelastic liquids. It is concluded that no satisfactory mathematical treatment is yet available for calculating the load-carrying capacity of such liquids. In thin-film lubrication, elastohydrodynamic calculations indicate that the lubricant film may be quite thick even under heavily loaded conditions, but discrepancies exist between calculation and experiment. These can be explained by assuming non-Newtonian behavior, or unusual viscoelastic effects, but the assumptions are largely unfounded. There is virtually a complete absence of data on the behavior of liquids under impact loading. Such data are needed to resolve whether thin-film lubrication is primarily chemical or primarily physical.

Effect of concentration dependence of viscosity on squeeze film lubrication

2020 ◽  
Vol 75 (6) ◽  
pp. 533-542
Author(s):  
Poosan Muthu ◽  
Vanacharla Pujitha
Keyword(s):  
Carrying Capacity ◽  
Iterative Procedure ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Convection Diffusion ◽  
Load Carrying ◽  
Newtonian Viscous Fluid ◽  
Nicolson Scheme ◽  
Human Joint ◽  
Film Lubrication

AbstractThe influence of concentration of solute particles on squeeze film lubrication between two poroelastic surfaces has been analyzed using a mathematical model. Newtonian viscous fluid is considered as a lubricant whose viscosity varies linearly with concentration of suspended solute particles. Convection-diffusion model is proposed to study the concentration of solute particles and is solved using finite difference method of Crank–Nicolson scheme. An iterative procedure is used to get the solution for concentration, pressure and velocity components in film region. It has been observed that load carrying capacity decreases as the concentration of solute particles in the fluid film decreases. Further, the concentration of suspended solute particles decreases as the permeability of the poroelastic plate increases and these results may be useful in understanding the mechanism of human joint.

Numerical investigation of squeeze film lubrication on bioinspired hexagonal patterned surface

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Binbin Su ◽  
Xianghe Zou ◽  
Lirong Huang
Keyword(s):  
Flow Rate ◽  
Carrying Capacity ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Two Dimensional ◽  
Working Mechanism ◽  
Content Type ◽  
Patterned Surface ◽  
Load Carrying ◽  
Film Lubrication

Purpose This paper aims to investigate the squeeze film lubrication properties of hexagonal patterned surface inspired by the epidermis structure of tree frog’s toe pad and numerically explore the working mechanism of hexagonal micropillar during the acquisition process of high adhesive and friction for wet contacts. Design/methodology/approach A two-dimensional elastohydrodynamic numerical model is employed for the squeezing contacts. The pressure distribution, load carrying capacity and liquid flow rate of the squeeze film are obtained through a simultaneous solution of the two-dimensional Reynolds equation and elasticity deformation equations. Findings Higher pressure is found to be longitudinally distributed across individual hexagonal pillar, with pressure peak emerging at the center of hexagonal pillar. Expanding the area density and shrinking the channel depth or initial film thickness will improve the magnitude of squeezing pressure. Relatively lower pressure is generated inside interconnected channels, which reduces the load carrying capacity of the squeeze film. Meanwhile, the introduction of microchannel is revealed to downscale the total mass flow rate of squeezing contacts. Originality/value This paper provides a good proof for the working mechanism of surface microstructures during the acquisition process of high adhesive and friction for wet contacts.

An Attempt to Provide a Unified Treatment of Tribology Through Load Carrying Capacity, Transport, and Continuum Mechanics

1980 ◽  
Vol 102 (2) ◽  
pp. 153-164 ◽  
Author(s):  
M. Godet ◽  
D. Play ◽  
D. Berthe
Keyword(s):  
High Temperature ◽  
Continuum Mechanics ◽  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
Third Body ◽  
Continuum Approach ◽  
Load Carrying ◽  
Solid Liquid ◽  
Film Lubrication ◽  
The Continuum

This paper attempts to give a unified treatment of experiments obtained with solid, liquid and boundary lubricants, different plastics, high temperature steels and elastomers. The argument is centered around third body role, load-carrying capacity, transport and continuum mechanics. This study suggests that an extension to general tribology of the continuum approach used in full film lubrication could be profitable.

scholarly journals MULTIGRID METHOD FOR THE SOLUTION OF COMBINED EFFECT OF VISCOSITY VARIATION AND SURFACE ROUGHNESS ON THE SQUEEZE FILM LUBRICATION OF JOURNAL BEARINGS

2017 ◽  
Vol 46 (1) ◽  
pp. 1-8
Author(s):  
Vishwanath B. Awati ◽  
Ashwini Kengangutti ◽  
Mahesh Kumar N.
Keyword(s):  
Surface Roughness ◽  
Carrying Capacity ◽  
Micropolar Fluid ◽  
Reynolds Equation ◽  
Multigrid Method ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Viscosity Variation ◽  
Film Lubrication

The paper presents, the multigrid method for the solution of combined effect of surface roughness and viscosity variation on the squeeze film lubrication of a short journal bearing operating with micropolar fluid. The modified Reynolds equation which incorporates the variation of viscosity in micropolar fluid is analysed using Multigrid method. The governing modified Reynolds equation is solved numerically for the fluid film pressure and bearing characteristics viz. load carrying capacity and squeeze time. The analysis of the results predicts that, the viscosity variation factor decreases the load carrying capacity and squeeze film time, resulting into a longer bearing life. The results are compared with the corresponding analytical solutions.

Failure of Thin Film Lubrication—The Effect of Running-In on the Load Carrying Capacity of Thin-Film Lubricated Concentrated Contacts

1981 ◽  
Vol 103 (2) ◽  
pp. 203-208 ◽  
Author(s):  
A. Begelinger ◽  
A. W. J. de Gee
Keyword(s):  
Thin Film ◽  
Carrying Capacity ◽  
Test Method ◽  
Engine Oil ◽  
Radius Of Curvature ◽  
Total Force ◽  
Initial Surface ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Film Collapse

The effect of running-in under low speed - high load conditions on the load carrying capacity at high speed of sliding crossed cylinders of steel AISI 52100, thin film lubricated with a marine diesel engine oil of 60°C, is described for three values of the initial composite roughness Rc, i.e. 0.14 μm, 0.42 μm and 0.71 μm. It is shown that—irrespective of the initial surface roughness—the surface of the (smaller) stationary cylinder becomes very smooth (Ra ≤ 0.1 μm), that of the (larger) rotating cylinder remaining virtually unaffected. As the local radius of curvature increases as a result of running-in, the load carrying capacity, expressed in terms of total force on the contact, increases considerably, i.e. 600 percent at Rc = 0.14 μm, 500 percent at Rc = 0.42 μm and 150 percent at Rc = 0.71 μm. This is not accompanied by a correspondingly large increase in Hertzian contact pressure at film collapse, pHc. In fact pHcincreases 45 percent at Rc = 0.14 μm and 15 percent at Rc = 0.42 μm and decreases 20 percent at Rc = 0.71 μm. It is further found that run-in surfaces show the phenomenon of delayed EHD-film collapse, meaning that the transition from the (partial) EHD to the scuffing regime may take from 1 to 40 s after application of the normal force. The test method should contribute significantly to the functional characterization of lubricants and—more in particular—running-in fluids, as candidates for use in concentrated contact situations.

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