Squeeze Film Performance in Parallel Rough Circular Disks Lubricated by Ferrofluid with Non-newtonian Couple Stress Effect

2013 ◽  
pp. 111-115
Author(s):  
H. A. Patel ◽  
M. P. Patel ◽  
H. C. Patel ◽  
G. M. Deheri
Keyword(s):  
Couple Stress ◽  
Squeeze Film ◽  
Stress Effect ◽  
Film Performance ◽  
Circular Disks

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.

Effects of piezo-viscous–coupled stress lubricant on the squeeze film performance of parallel triangular plates

2019 ◽  
Vol 234 (9) ◽  
pp. 1514-1521 ◽  
Author(s):  
H Aminkhani ◽  
M Daliri
Keyword(s):  
Pressure Distribution ◽  
Carrying Capacity ◽  
Couple Stress ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Film Performance ◽  
Pressure Dependency ◽  
Load Carrying ◽  
Viscosity Variation ◽  
Coupled Stress

The paper shows the combined effects of couple stress fluids and lubricant viscosity variation with pressure in squeeze film performance of parallel triangular plates. By solving Reynolds equation and using perturbation method, the pressure distribution is obtained with consideration of viscosity variation with pressure. Also, with integrating pressure in the film region, load-carrying capacity is derived. A fourth-order Rang–Kutta is used to solve the nonlinear differential equation between lubricant film thickness and time. Various cases of couple stress, iso-viscous and piezo-viscous contributions are analyzed. According to the results, it is found that using couple stress fluid as a lubricant and considering viscosity–pressure dependency will increase characteristics of the squeeze film such as load-carrying capacity, pressure distribution, and triangular plates moving time, significantly as compared to the classical Newtonian iso-viscous lubricant.

Squeeze film performance of parallel annular plates by ferrofluid couple stress lubricant considering effects of rotational inertia

2017 ◽  
Vol 69 (6) ◽  
pp. 990-994
Author(s):  
Nioosha Ghasemi Dolatsara ◽  
Maghsood Daliri ◽  
Moharram Shameli
Keyword(s):  
Couple Stress ◽  
Couple Stress Theory ◽  
Squeeze Film ◽  
Rotational Inertia ◽  
Film Performance ◽  
Content Type ◽  
Stress Theory ◽  
Annular Plates ◽  
Inertia Parameter ◽  
Film Characteristics

Purpose The purpose of this paper is to investigate squeezing and rotating motions between two parallel annular discs lubricated by ferro-fluid couple stress lubricant in the presence of a uniform magnetic field. Design/methodology/approach Based upon the Stokes couple stress theory and ferro-hydrodynamic model of Shliomis, squeeze film characteristics between two parallel annular discs are obtained. Findings According to the results, it is found that the combined effects of couple stress and ferro-fluid lubricant increase squeeze film performance with respect to the classical Newtonian lubricant. However, an increase in the rotational inertia parameter reduces squeeze film characteristics. Originality/value This paper is relatively original and describes the squeeze film characteristics between two parallel annular discs with rotational inertia, couple stress and ferro-fluid lubricant 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.

scholarly journals Ferrofluid Based Squeeze Film Lubrication between Rough Stepped Plates with Couple Stress Effect

2018 ◽  
Vol 11 (3) ◽  
pp. 597-612 ◽  
Author(s):  
Y. D. Vashi ◽  
R. M. Patel ◽  
G. M. Deheri ◽  
◽  
◽  
...  
Keyword(s):  
Couple Stress ◽  
Squeeze Film ◽  
Stress Effect ◽  
Film Lubrication

Acoustic radiation simulation and pre-stress effect on compact acoustic levitation platform

2019 ◽  
Vol 33 (07) ◽  
pp. 1950080 ◽  
Author(s):  
Bin Wei ◽  
Yongyong He ◽  
Wei Wang
Keyword(s):  
Pressure Distribution ◽  
Acoustic Radiation ◽  
Near Field ◽  
Parameters Optimization ◽  
Squeeze Film ◽  
Acoustic Levitation ◽  
Stress Effect ◽  
Biological Engineering ◽  
Loop Control ◽  
Close Loop Control

In order to satisfy the requirements of precise components with tidiness, low power and high stability in the field of biological engineering, medical equipment and semiconductors etc. a pre-stress acoustic transport prototype without horn was proposed in this paper. The mechanism of levitation and transport which is driven by orthogonal waves was revealed by the analysis of waveform and squeeze film characteristics in high-frequency exciting condition; also, the electric, solid and acoustic coupled finite element method (FEM) was established to investigate the effect of pre-stress and acoustic pressure distribution in the near field. The levitation and driving capacity of near field acoustic levitation (NFAL) transport platform without horns can be proved in this experiment and further to achieve the goal of parameters optimization. The theoretical and experimental results indicate that the pre-stress has a significant effect on resonant frequency and levitating stability, the pre-stress are determined by the DC voltage offset which is related to the system working point so that we cannot increase the offset and exciting voltage unlimitedly to improve the stability. At the same time, the calculated pressure distribution of acoustic radiation can generally reflect the regional bearing capacity in near and far field for levitation. These achievements can partly solve the problem of accuracy design of prototype and thickness of gas film, supporting for accuracy close loop control of levitating height.

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