scholarly journals Effect of Surface Roughness on the Squeeze Film Lubrication of Finite Poroelastic Partial Journal Bearings with Couple Stress Fluids: A Special Reference to Hip Joint Lubrication

2014 ◽  
Vol 2014 ◽  
pp. 1-13
Author(s):  
N. B. Naduvinamani ◽  
G. K. Savitramma
Keyword(s):  
Surface Roughness ◽  
Couple Stress ◽  
Stochastic Theory ◽  
Couple Stress Fluid ◽  
Squeeze Film ◽  
Hip Joints ◽  
Random Roughness ◽  
Couple Stresses ◽  
Longitudinal Roughness ◽  
Transverse Roughness

A simplified mathematical model has been developed for understanding the combined effects of surface roughness and couple stresses on the squeeze film behavior of poroelastic bearings in general and that of hip joints in particular. The cartilage is modeled as biphasic poroelastic matrix and synovial fluid is modeled as couple stress fluid. The modified form of averaged Reynolds equation which incorporates the randomized roughness structure as well as elastic nature of articular cartilage with couple stress fluid as lubricant is derived. For the study of rough surfaces, Christensen's stochastic theory is used to study the effect of two types of one-dimensional random roughness, namely, longitudinal roughness pattern and the transverse roughness pattern. The averaged film pressure distribution equations are solved numerically by using the conjugate gradient method. It is observed that the surface roughness effect is dominant and pattern dependent and the influence of couple stresses is to improve the joint performance.

Squeeze film behavior in porous transversely circular stepped plates with a couple stress fluid

2016 ◽  
Vol 33 (2) ◽  
Author(s):  
Santhana Krishnan Narayanan ◽  
A Chamkha ◽  
Sundarammal Kesavan
Keyword(s):  
Surface Roughness ◽  
Couple Stress ◽  
Design Methodology ◽  
Reynolds Equation ◽  
Closed Form Solution ◽  
Stochastic Theory ◽  
Classical Case ◽  
Form Solution ◽  
Couple Stress Fluid ◽  
Squeeze Film

Purpose The purpose of this work is to carry our a study of the effect of surface roughness on squeeze film behavior between two transversely circular stepped plates with couple stress lubricant when the upper circular stepped plate has porous facing which approaches the lower plate with uniform velocity. Design/methodology/approach The modified Stochastic Reynolds equation is derived for Christensen Stochastic theory for the rough surfaces. Closed form solution of the Stochastic Reynolds equation is obtained in terms of Fourier-Bessel series. Findings It is found that the effect of couple stress fluid and surface roughness is more pronounced compared to classical case. Originality/value The problem is original that it consider a couple stress fluid in this type of applications.

scholarly journals Effect of Surface Roughness and Couple Stresses on Squeeze Films between Curved Annular Plates

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Dhanapal P. Basti
Keyword(s):  
Surface Roughness ◽  
Couple Stress ◽  
Fluid Model ◽  
Stochastic Theory ◽  
Squeeze Film ◽  
Couple Stresses ◽  
Annular Plates ◽  
The Mean ◽  
Film Characteristics ◽  
Effect Of Surface

The combined effects of couple stresses and surface roughness patterns on the squeeze film characteristics of curved annular plates are studied. The Stokes (1966) couple stress fluid model is included to account for the couple stresses arising due to the presence of microstructure additives in the lubricant. In the context of Christensen's (1969) stochastic theory for the lubrication of rough surfaces, two types of one-dimensional roughness patterns (circumferential and radial) are considered. The governing modified stochastic Reynolds type equations are derived for these roughness patterns. Expressions for the mean squeeze film characteristics are obtained. Numerical computations of the results show that the circumferential roughness pattern on the curved annular plate results in more pressure buildup whereas performance of the squeeze film suffers due to the radial roughness pattern for both concave and convex pads. Further the squeeze film time is longer (shorter) for the circumferential (radial) roughness patterns. Improved squeeze film characteristics are predicted for the couple stress lubricant.

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.

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.

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

A Comparison of Porous Structures on the Performance of a Slider Bearing with Surface Roughness in Couple Stress Fluid Film Lubrication

2015 ◽  
Vol 813-814 ◽  
pp. 921-937
Author(s):  
P.S. Rao ◽  
Santosh Agarwal
Keyword(s):  
Surface Roughness ◽  
Carrying Capacity ◽  
Couple Stress ◽  
Type Equation ◽  
Random Variable ◽  
Couple Stress Fluid ◽  
Load Carrying Capacity ◽  
Porous Structures ◽  
Slider Bearing ◽  
Load Carrying

This paper presents the theoretical study and analyzes the comparison of porous structures on the performance of a couple stress fluid based on rough slider bearing. The globular sphere model of Kozeny-Carman and Irmay’s capillary fissures model have been subjected to investigations. A more general form of surface roughness is mathematically modeled by a stochastic random variable with non-zero mean, variance and skewness. The stochastically averaged Reynolds type equation has been solved under suitable boundary conditions to obtain the pressure distribution in turn which gives the expression for the load carrying capacity, frictional force and coefficient of friction. The results are illustrated by graphical representations which show that the introduction of combined porous structure with couple stress fluid results in an enhanced load carrying capacity more in the case of Kozeny-Carman model as compared to Irmay’s model.

Effect of surface roughness on magneto-hydrodynamic couple-stress squeeze film lubrication between circular stepped plates

2012 ◽  
Vol 24 (2) ◽  
pp. 61-74 ◽  
Author(s):  
N. B. Naduvinamani ◽  
B. N. Hanumagowda ◽  
A. Siddangouda
Keyword(s):  
Surface Roughness ◽  
Couple Stress ◽  
Squeeze Film ◽  
Film Lubrication ◽  
Effect Of Surface
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