scholarly journals Particularities of the Pseudo-Plastic Lubrication, with Application to the Sinovial Liquid

2015 ◽  
Author(s):  
I. Radulescu ◽  
A.V. Radulescu ◽  
J. Javorova
Keyword(s):  
Friction Coefficient ◽  
Synovial Fluid ◽  
Film Thickness ◽  
Pressure Distribution ◽  
Power Law ◽  
Hip Joint ◽  
Load Capacity ◽  
Squeeze Film ◽  
Power Law Model ◽  
Spherical Surfaces

The present paper proposes a new model for lubrication of the hip joint with hyaluronan solutions, considering the squeeze film process of non-Newtonian fluid between rigid spherical surfaces. The heological model that approximately describes the behaviour of the synovial fluid is the power law model. For the considered case, the pressure distribution, the load capacity, the film thickness and the friction coefficient have been determinated. The conclusions of the paper offer an explication to the development of the osteoarthritis and to the problems of the arthritic patients.

Squeeze-Film Behavior in Porous Circular Disks

1974 ◽  
Vol 96 (2) ◽  
pp. 206-209 ◽  
Author(s):  
P. R. K. Murti
Keyword(s):  
Adverse Effect ◽  
Film Thickness ◽  
Pressure Distribution ◽  
Finite Time ◽  
Reynolds Equation ◽  
Load Capacity ◽  
The Other ◽  
Squeeze Film ◽  
Permeability Parameter ◽  
Circular Disks

The squeeze film behavior between two circular disks is analyzed when one disk has a porous facing and approaches the other disk with uniform velocity. The modified Reynolds equation governs the pressure in the film region while the pressure in the porous facing satisfies the Laplace equation. These equations are solved in a closed form and expressions are derived for pressure distribution, load capacity, and time of approach for the plates in terms of Fourier-Bessel series. It is found that an enhanced value for the permeability parameter diminishes the pressure over the entire disk and also evens out the pressure distribution; however, there is an adverse effect on the load capacity and time of approach. Unlike in the nonporous case, the entire fluid can be squeezed out in a finite time resulting in actual contact of the disks. The porous effects are shown to predominate at very low film thickness values.

Hydromagnetic Squeeze Films Between Porous Rectangular Plates

1973 ◽  
Vol 95 (3) ◽  
pp. 394-398 ◽  
Author(s):  
P. C. Sinha ◽  
J. L. Gupta
Keyword(s):  
Magnetic Field ◽  
Film Thickness ◽  
Pressure Distribution ◽  
Transverse Magnetic Field ◽  
Theoretical Study ◽  
Load Capacity ◽  
Transverse Magnetic ◽  
Squeeze Film ◽  
Rectangular Plates

A theoretical study is made of the squeeze film behavior between two rectangular plates, one with a porous facing, in the presence of a uniform transverse magnetic field. Results are presented for pressure distribution, load capacity, and film thickness as functions of time. It is shown that the application of a magnetic field improves the squeeze-film action.

A Generalized Squeezing Flow of a Power-Law Fluid Between Two Plane Annuli

1986 ◽  
Vol 108 (1) ◽  
pp. 80-85 ◽  
Author(s):  
A. F. Elkouh ◽  
N. J. Nigro ◽  
A. Glowacz
Keyword(s):  
Pressure Distribution ◽  
Newtonian Fluid ◽  
Power Law ◽  
Load Capacity ◽  
Numerical Results ◽  
Squeezing Flow ◽  
Power Law Model ◽  
Power Law Fluid ◽  
Newtonian Behavior

A generalization of the problem of laminar squeezing flow of a non-Newtonian fluid between plane annular surfaces is presented. The generalization considers the effect of difference in the pressures at the inner and outer boundaries. The fluid is assumed to be incompressible, and the non-Newtonian behavior of the fluid is described by a power-law model. Expressions for the pressure distribution and load capacity are presented along with tables that are used for obtaining numerical results.

An Investigation Into the Influence of Fluid Viscoelasticity in a Squeeze Film Bearing

1978 ◽  
Vol 100 (1) ◽  
pp. 56-64 ◽  
Author(s):  
John A. Tichy ◽  
Ward O. Winer
Keyword(s):  
Molecular Weight ◽  
Film Thickness ◽  
High Molecular Weight ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Surface Film ◽  
Free Fall ◽  
Squeeze Film ◽  
Delayed Response ◽  
High Molecular Weight Polymers

This investigation concerns a prediction of the behavior of viscoelastic fluids in a parallel circular squeeze film with a constant approach velocity, and a comparison to experimental results. The squeeze film geometry has direct application to unsteady hydrodynamic lubrication. The analysis predicts that load capacity of a viscoelastic fluid may be increased due to normal stress effects or decreased due to a delayed response of shear stress to a change in shear rate. Ten tested fluids include Newtonian control fluids, silicone fluids, high molecular weight polymers in petroleum oils, and extremely high molecular weight polymers in water and glycerin. The experimental squeezing is accomplished by the free fall of a cylindrical steel rod along its axis toward a stationary opposing surface. Film thickness, velocity of approach and load are measured. The velocity of approach is essentially constant in the range of film thickness considered. The water-glycerin-polymer solutions exhibited load capacity increases up to 33 percent, while the petroleum-polymer and silicone fluids showed decreases to 23 percent. It appears that viscoelastic effects cannot account for the reported improved bearing performance of polymer-additive lubricants.

Numerical Investigation on the Mixed Lubrication Performance of Water-Lubricated Coupled Journal and Thrust Bearings

2019 ◽  
Author(s):  
Yanfeng Han ◽  
Guo Xiang ◽  
Jiaxu Wang
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Thrust Bearing ◽  
Journal Bearing ◽  
Load Capacity ◽  
Hydrodynamic Pressure ◽  
Mixed Lubrication ◽  
Eccentricity Ratio ◽  
Thrust Bearings ◽  
Lubrication Performance

Abstract The mixed lubrication performance of water-lubricated coupled journal and thrust bearing (simplified as coupled bearing) is investigated by a developed numerical model. To ensure the continuity of hydrodynamic pressure and flow at the common boundary between the journal and thrust bearing, the conformal transformation is introduced to unify the solution domain of the Reynolds equation. In the presented study, the coupled effects between the journal and thrust bearing are discussed. The effects of the thrust bearing geometric film thickness on the mixed lubrication performance, including the load capacity, contact load and friction coefficient, of the journal bearing are investigated. And the effects of the journal bearing eccentricity ratio on the mixed lubrication performance of the thrust bearing are also investigated. The simulated results indicate the mutual effects between the journal and thrust bearing cannot be ignored in the coupled bearing system. The increasing thrust bearing geometric film thickness generates a decrease in load capacity of journal bearing. There exists an optimal eccentricity ratio of journal bearing that yields the minimum friction coefficient of the thrust bearing.

The Effect of Porosity of Articular Cartilage on the Lubrication of a Normal Human Hip Joint

1992 ◽  
Vol 206 (3) ◽  
pp. 117-124 ◽  
Author(s):  
Z M Jin ◽  
D Dowson ◽  
J Fisher
Keyword(s):  
Articular Cartilage ◽  
Synovial Fluid ◽  
Film Thickness ◽  
Hip Joint ◽  
Elastic Material ◽  
Single Phase ◽  
Reynolds Equation ◽  
Lubricant Film ◽  
Lubricant Film Thickness ◽  
Normal Human

The effect of porosity of articular cartilage on the lubrication of a normal human hip joint has been studied. The poroelasticity equation of articular cartilage and the modified Reynolds equation for the synovial fluid lubricant have been successfully solved under squeezefilm motion and for the conditions experienced in a normal human hip joint. It has been shown that porosity of the articular cartilage depletes the lubricant film thickness, rather than increasing it, particularly when the lubricant film thickness becomes small. Furthermore, it has been shown that articular cartilage can be treated as a single-phase incompressible elastic material in the lubrication modelling under physiological walking conditions.

Elastohydrodynamic lubrication analysis of ultra-high molecular weight polyethylene hip joint replacements under squeeze-film motion

2001 ◽  
Vol 215 (2) ◽  
pp. 141-151 ◽  
Author(s):  
M Jagatia ◽  
D Jalali-Vahid ◽  
Z M Jin
Keyword(s):  
Molecular Weight ◽  
Femoral Head ◽  
Film Thickness ◽  
Hip Joint ◽  
Elastohydrodynamic Lubrication ◽  
Squeeze Film ◽  
Acetabular Cup ◽  
Joint Replacements ◽  
Hip Joint Replacements ◽  
Ultra High Molecular Weight

Elastohydrodynamic lubrication was analysed under squeeze-film or normal approach motion for artificial hip joint replacements consisting of an ultra-high molecular weight polyethylene (UHMWPE) acetabular cup and a metallic or ceramic femoral head. A simple ball-in-socket configuration was adopted to represent the hip prosthesis for the lubrication analysis. Both the Reynolds equation and the elasticity equations were solved simultaneously for the lubricant film thickness and hydrodynamic pressure distribution as a function of the squeeze-film time was solved using the Newton-Raphson method. The elastic deformation of the UHMWPE cup was calculated by both the finite element method and a simple equation based upon the constrained column model. Good agreement of the predicted film thickness and pressure distribution was found between these two methods. A simple analytical method based upon the Grubin -Ertel-type approximation developed by Higginson in 1978 [1] was also applied to the present squeeze-film lubrication problem. The predicted squeeze-film thickness from this simple method was found to be remarkably close to that from the full numerical solution. The main design parameters were the femoral head radius, the radial clearance between the femoral head and the acetabular cup, and the thickness and elastic modulus for the UHMWPE cup; the effects of these parameters on the squeeze-film thickness generated in current hip prostheses were investigated.

Squeeze-Film Behavior for Porous Annular Disks

1970 ◽  
Vol 92 (4) ◽  
pp. 593-596 ◽  
Author(s):  
Hai Wu
Keyword(s):  
Film Thickness ◽  
Pressure Distribution ◽  
Carrying Capacity ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Annular Disks

An analysis is made of the squeeze-film behavior between two annular disks when one disk has a porous facing. The problem is solved analytically. Results are presented for pressure distribution, load-carrying capacity, and film thickness as functions of time.

Influence of Laser Micro-Mesh Texturing on the Tribological Performance in an EHL Point Contact

2007 ◽  
Vol 353-358 ◽  
pp. 796-800
Author(s):  
Xiao Wang ◽  
Jian Li ◽  
Wei Chen ◽  
Lan Cai ◽  
Jian Ying Zhu
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Pressure Distribution ◽  
Reynolds Equation ◽  
Point Contact ◽  
Tribological Performance ◽  
Design And Optimization ◽  
Thickness Profile ◽  
Wide Range ◽  
Key Factor

Fabricating surfaces with controlled micro-geometry may be an effective approach to improved tribological performance. In this paper, the effect of laser surface micro-mesh texturing on the tribological performance is investigated theoretically with numerical solution of EHL point contact. In the theoretical model, the Reynolds equation is used as the governing equation. Well controlled micro-mesh texturing is described in film thickness equation. By Full Multi-Grid (FMG) method, the solutions of film thickness profile and pressure distribution map are present over a wide range of texturing parameters. The influence of width, depth and orientation of mesh texturing on the friction coefficient is analyzed. Result shows that, the film thickness profile and pressure distribution are sensitive to the parameters of micro-mesh texturing. The curve result of friction coefficient under two load conditions indicated that the parameters of mesh are key factor for texturing design. Solutions demonstrate the ability of numerical simulation on the design and optimization of surface mesh texturing.

An Analysis of the Squeeze Film Between Porous Rectangular Plates

1972 ◽  
Vol 94 (1) ◽  
pp. 64-68 ◽  
Author(s):  
Hai Wu
Keyword(s):  
Film Thickness ◽  
Pressure Distribution ◽  
Laplace Equation ◽  
Carrying Capacity ◽  
Reynolds Equation ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Rectangular Plates ◽  
Load Carrying ◽  
In Series

The squeeze film between two rectangular plates when one has a porous facing is studied theoretically. The problem is described by the modified Reynolds equation in the film region and the Laplace equation in the porous region. Results are presented for pressure distribution, load-carrying capacity, and film thickness as functions of time in series form. The effect of the porous facing on the squeeze film behavior is discussed and found to be important.

Sign in / Sign up

Export Citation Format

Share Document