Impact of various and arbitrary porous structure in the study of squeeze step bearing lubricated with magnetic fluid considering variable magnetic field

Abstract

The aim of this paper is to study the impact of various and arbitrary porous structure on the performance of the step bearing lubricated with magnetic fluid. The paper also studied about the effect of squeeze velocity which appears when two lubricated surfaces approaches to each other with a normal velocity. The porous layer (region or wall or matrix) is attached to the lower flat impermeable plate (surface or disc). Two porous structure models given by Kozeny-Carman (a globular sphere model) and Irmay (a capillary fissures model) are considered for the study. The upper surface is a step surface approaching to lower one. The magnetic field considered here is variable and oblique to the lower plate. Expressions for pressure under the step surfaces and load-carrying capacity are obtained. The dimensionless load-carrying capacity $\overline{W}$ is calculated for various values of permeability, porous width, length of first step of the bearing, width of the film region, and strength of magnetic field. From the results it is observed that $\overline{W}$ increases with the increase of the length of the first step and with the increase of K (which leads increase of H) for both the models. It is also observed that permeability and width of porous matrix have almost no effect on $\overline{W}$ . In the case of width of the film region, it is observed that $\overline{W}$ attains same behavior whether film thickness is small or large. Moreover, calculation shows that globular sphere model have better performance for $\overline{W}$ than capillary fissures model. Thus, it is suggested to have a design of porous squeeze step bearing with globular spheres in the porous region considering variable magnetic field strength H of order 10⁴.