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1

Squeeze film based magnetic fluid in between porous circular disks with sealed boundary

100%

Deheri G. M. , Patel R. M.

International Journal of Applied Mechanics and Engineering

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2006

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tom Vol. 11, no 4

803-812

EN

Efforts have been made to study the effect of the magnetic fluid lubricant and the sealing of the boundary for the squeeze film between two circular disks when the upper disk having a porous facing with its boundary sealed, approaches the non-porous lower disk normally. The modified Reynolds equations for the fluid region and the governing Laplacian equation for the pressure in a porous region are solved with appropriate boundary conditions. Expressions are obtained for pressure, load carrying capacity and the response time. The results are presented graphically. The combined effect of the magnetic fluid lubricant and sealing of the boundary increases the load carrying capacity significantly and hence the performance of the bearing can be enhanced considerably by sealing the boundary and taking a magnetic fluid as lubricant.

2

Magnetic fluid based squeze film behaviour between rotating porous circular plates with a concentric circular pocket and surface roughness effects

100%

Patel R. M. , Deheri G. M.

International Journal of Applied Mechanics and Engineering

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2003

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tom Vol. 8, no 2

271-277

EN

Efforts have been made to analyze the magnetic fluid based squeeze film between rotating porous circular plates with a concentric pocket. The porous housing is considered to be elastically negligibly deformable with its contact surface rough. The stochastic film thickness characterizing the roughness is considered to be asymmetric with zero mean and non-zero variance. The modified Reynolds' equation is solved in order to get pressure distribution which in turn, is used to obtain the expression for load carrying capacity. Then by making use of this expression we find the response time. These expressions are numerically computed and the results are presented graphically as well as in a tabular form. It is observed that the presence of pocket and the roughness of the surfaces affect the performance of the bearing adversely. However, the performance of the bearing gets enhanced due to negatively skewed roughness and the magnetic fluid.

3

Transversely rough slider bearings with squeeze film formed by a magnetic fluid

80%

Deheri G. M. , Andharia P. I. , Patel R. M.

International Journal of Applied Mechanics and Engineering

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2005

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tom Vol. 10, no 1

53-76

EN

In this article it has been sought to study the effect of transverse roughness on the behaviour of slider bearings with squeeze film formed by a magnetic fluid. The roughness of the bearing surface is modelled by a stochastic random variable with non zero mean, variance and skewness. The associated Reynolds' equation is stochastically averaged with respect to the random roughness parameter. Results for bearing performance characteristics such as load carrying capacity, center of pressure, frictional force and coefficient of friction for different values of mean, standard deviation and measure of symmetry are numerically computed. In order to decipher the quantitative effect of roughness on the performance characteristics four different shapes namely; plane slider, exponential slider, hyperbolic slider and secant slider for the lubricant film are considered. The results are presented graphically. It is noticed that the bearing suffers on account of transverse surface roughness. The results show that the use of a magnetic fluid as lubricant increases the load carrying capacity, decreases the coefficient of friction and affects the center of pressure marginally. It is further observed that the effect of magnetization on the plane and secant shaped bearings is nominal while the effect on exponential and hyperbolic slider bearing is significant. In addition it is easily seen that by increasing the strength of the magnetic field the adverse impact on the bearing due to roughness can be minimized.

4

Performance of magnetic fluid based rotating rough circular step bearings

80%

Patel H. C. , Deheri G. M. , Patel R. M.

International Journal of Applied Mechanics and Engineering

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2008

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tom Vol. 13, no 2

441-455

EN

An attempt has been made to analyze the performance of a magnetic fluid based rotating rough circular step bearing. The roughness of the bearing surface is modeled by a stochastic random variable with non zero mean, variance and skewness. The associated Reynolds' equation is solved with appropriate boundary conditions to obtain the pressure distribution, which in turn, is used to get the load carrying capacity leading to the calculation of response time. Results are presented graphically as well as in a tabular form. It is noticed that the bearing suffers on account of transverse surface roughness. This article makes it clear that pressure, load carrying capacity and response time increase with increasing the magnetization parameter. However, the negatively skewed roughness and radii ratio induce better performance. It is noticed that the load carrying capacity decreases when both plates rotate in the same direction. This trend reverses when the plates move in the opposite direction. This article reveals that the negative effect caused by porosity and roughness can be compensated to a considerable extent by the positive effect induced by the magnetization parameter and the aspect ratio in the case of negatively skewed roughness when the plates rotate in opposite direction.

5

Effect of surface roughness on the performance of hydromagnetic squeeze film between conducting porous infinitely long rectangular plates

80%

Vadher P. A. , Deheri G. M. , Patel R. M.

International Journal of Applied Mechanics and Engineering

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2008

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tom Vol. 13, no 2

473-498

EN

An attempt has been made to study and analyze the performance of a hydromagnetic squeeze film between conducting porous rough infinitely long rectangular plates with electrically conducting lubricant in the presence of a transverse magnetic field. The bearing surfaces are assumed to be transversely rough. The random roughness is characterized by a stochastic random variable with non zero mean, variance and skewness. The associated Reynolds' equation is then stochastically averaged with respect to the random roughness parameter. This equation is solved with appropriate boundary conditions to find the pressure distribution, which is then used to obtain the load carrying capacity. Lastly, the response time is calculated. The results are presented graphically as well as in a tabular form. It is seen that the bearing system gets affected adversely owing to transverse surface roughness. But variance (-ve) tends to increase the load carrying capacity. Also, the bearing system resists an enhanced performance due to hydromagnetization. In addition, the load carrying capacity increases considerably due to conductivity while it decreases with respect to the aspect ratio The combined effect of porosity, the aspect ratio and the standard deviation associated with roughness is substantially adverse. However, this negative effect can be compensated to some extent by hydromagnetization and conductivity in the case of negatively skewed roughness. It is also observed that the bearing with magnetic field can support a load even when there is absence of flow. This investigation makes it plain and clear that roughness must be given due consideration while designing the bearing system.