Numerical Study on the Interaction of Transverse and Longitudinal Roughness on Elastohydrodynamic Lubrication Contact Surfaces With Different Thermal Conductivities and Elastic Moduli

The interaction and surface features between point contact surfaces composed of longitudinal roughness with infinite or finite length and transverse roughness were discussed based on a transient non-Newtonian thermal elastohydrodynamic lubrication (EHL) model. Each surface shape is greatly affected by the difference in elastic moduli, thermal conductivities, and velocities of both contact surfaces. There is a large difference in pressure behavior when the transverse roughness is in contact with the longitudinal roughness with finite length and when it is in contact with the longitudinal roughness with infinite length. In the contact between surfaces with infinitely long longitudinal and transverse roughness, the friction coefficient is lower when the surface with longitudinal roughness has a low thermal conductivity than when it has a high thermal conductivity. Furthermore, the pressure fluctuation is larger when the transverse roughness surface has a high thermal conductivity than when it has a low thermal conductivity.

Lubrication of Rough Short Bearing on Shliomis Model by Ferrofluid Considering Viscosity Variation Effect

This study aims to explore the impact caused by change in viscosity and the roughness of a bearing surface on a ferrofluid lubrication of Shliomis model for short bearing. Based on this model and the Tipei (1962) model, a new resultant Reynolds equation has been found that shows thermal variation. The Christensen and Tonder models have been taken to derive the transverse roughness stochastically. An assumed mean has been taken for the probability density function with a non-zero value. This value is assigned to a random variable that measures the bearing’s surface roughness. This creates a more realistic situation that can have a lot of field applications. The model defines the problem mathematically while defining boundary conditions. It also uses the Simpson’s method to derive a conclusion. The results thus obtained are discussed in terms of pressure distribution and load bearing capacity. The graphical results obtained suggest that in the presence of magnetization, there is a significant enhance in the load bearing capacity. This positive effect can easily nullify the negative impact of the thermal effect. The short bearing approximation shown here is an example of the probable applications. Ferrofluids in the presence of magnetic fields significantly enhance the performance of a short bearing.

Performance evaluation of rough thrust pad bearing under thermo-elastohydrodynamic lubrication using an improved iterative method

The asperities present on interacting surfaces of a bearing influence the film formation when the oil film becomes thinner and thinner. The aim of this article is to study the effect of stochastic roughness on bearing performance under thermo-piezoviscous and elastic condition using an average flow model. To investigate the present operating conditions, progressive mesh densification method as a fast and simple algorithm has been applied. The results obtained indicate that transverse roughness generates higher pressure compared to other orientational roughness at various film thicknesses. Maximum pressure, mass flow rate and load capacity are larger in transverse roughness compared to other orientational roughness for all values of hydrodynamic roughness parameters. A large sensitivity in load capacity for transverse orientation compared to longitudinal at higher film thickness and small film thickness ratios are witnessed. The frictional coefficient in longitudinal orientation is large compared to transverse orientation at all values of film thickness ratio and step ratios. Materials with low elastic modulus undergo large deformation, resulting in generation of two sharp pressure peaks. These results may possess good acceptability to practical applications for studying the effect of surface roughness under thermo-elastohydrodynamic lubrication condition.

Assessment of the transverse roughness of the thin-walled cooler for the robot control system made using CAM programming

The article deals with design and design of a thin-walled heat sink for the robot control system, the measurement of the transverse roughness of the touch surfaces and the programming procedure in Autodesk Inventor 2019 software. In this software, a design of the 3D model of the heat sink generated based on power supply and NC code generation for the Fanuc control system. The production it-self carried out on the CNC Vertical Machining Center Pinnacle 2100 with this control system. The longitudinal surface roughness was measured with a Mi-tutoyo SJ 400 dredger and the measurement result was the maximum Ra = 0.69 μm and Rz = 4.1 μμm.

Ferro Fluid Based Rough Porous Tilted Pad Bearing with Slip Effect

The focus of this paper is to propose an innovative mathematical model, which describes the influence of slip and transverse roughness on a hydromagnetic squeeze film in porous tilted pad bearing. The stochastic model of Christensen and Tonder is, applied to evaluate the effect of surface roughness. Beavers and Joseph slip model takes the care of slip effect. Applying these models which governing the fluid pressure; is solved for the calculation of load support. The closed form solution is, obtained for the pressure and load capacity as a function of various physical parameters. The effect of such parameters is, discussed through graphical representations. The computations indicate that slip has to be at minimum for any upgrading in the bearing design. Besides, the absence of flow fails to keep away the bearing from supporting good amount of load, which does not happen in the case of traditional lubricant.

Effects of Surface Roughness and Non-Newtonian Micropolar Fluid Squeeze Film between Conical Bearings

Based on the micropolar fluid models of Eringen and Christensen’s stochastic theories, the analysis of the effects of surface roughness and the squeeze film lubrication problems between conical bearings are presented. The concerned nondimensional Reynolds equation is solved with appropriate boundary conditions in dimensionless form to find the pressure distribution, which is then used to obtain the expression for load-carrying capacity, paving the way for the calculation of response time. Computed values of pressure, load capacity, and response time are displayed in graphical form. This investigation reveals that the bearing system admits an improved performance as compared with that of a bearing system working with a conventional lubricant. According to the results, the effects of transverse roughness provide an increase in the bearing characteristics as compared with the smooth bearing lubricated with micropolar fluid whereas the influences of longitudinal roughness yield a reversed trend. The quantifiable effects of rough surfaces and non-Newtonian fluids on bearing performances are more pronounced for the roughness and micropolar parameters.