Rheology Of Lubricants Research Articles

High Pressure Rheology of Lubricants (Part 4)

High Pressure Rheology of Lubricants (Part 4)

High Pressure Rheology of Lubricants (Part 7)

High Pressure Rheology of Lubricants (Part 7)

High Pressure Rheology of Lubricants (Part 2)

High Pressure Rheology of Lubricants (Part 2)

Impact of oxidation on rheology and tribology of sustainable lubricants for electromechanical drive systems

AbstractThe rheological and tribological properties of environmentally compatible lubricants of different bases (native oil, synthetic ester, polyalkylene glycol‐containing oil) compared to a conventional, mineral oil‐based lubricant are investigated in order to develop toxicologically harmless and technically suitable lubricants for electromechanical drives. The aging of the oil is also considered. The results of this study reveal that the properties of polyalkylene glycol‐containing and synthetic ester‐based lubricants have the potential to act as substitutes for lubricants containing mineral oil. By examining and improving the properties of sustainable lubricants, gear oils that are partially or totally non‐mineral oil based will be highly attractive in the future.

High Pressure Rheology of Lubricants (Part 1)

High Pressure Rheology of Lubricants (Part 1)

High Pressure Rheology of Lubricants (Part 5)

High Pressure Rheology of Lubricants (Part 5)

Ensuring reliable operation of the hydraulic unit through the laws of contact hydrodynamics

The article discusses the basic laws of contact hydrodynamics, which studies complex phenomena occurring in the lubricating layer separating the elastically deformable surfaces of various parts, and thus solves the complex problem of hydrodynamics, elasticity theory, thermodynamics, rheology of lubricants and materials science. For a long time, contact hydrodynamics was considered a secondary direction in hydraulic engineering, however, the main aspects of contact hydrodynamics allow determining the thickness of the lubricating layer in the elastic metal-plastic segments of the hydraulic unit bearings, ensuring the reliability and durability of their operation. Thus, contact hydrodynamics allowed us to gain a positive experience of long-term operational tests of elastic metal-plastic segments in the supports of hydraulic units of the largest hydroelectric power plants. In addition, contact hydrodynamics solved the problem of transferring all hydraulic units of large hydroelectric power plants of the country from rigid babbit supports to elastic composite ones; and all newly built hydro generators should be equipped with elastic segments of a new design.

Effect of slip boundary condition and non-newtonian rheology of lubricants on the dynamic characteristics of finite hydrodynamic journal bearing

In the present study, the influence of various slip zone locations on the dynamic stability of finite hydrodynamic journal bearing lubricated with non-Newtonian and Newtonian lubricants has been investigated. Linearized equation of motion with free vibration of rigid rotor has been used to find the optimum location of the slip region with maximum stability margin limit. It has been observed that bearing with interface of slip and no-slip region near the upstream side of minimum film-thickness location is effective in improving the direct and cross stiffness coefficient, critical mass parameter, and critical whirling speed. The magnitude of dynamic performance parameters with slip effect is highly dependent on the rheology of lubricant. Shear-thinning lubricants combined with slip boundary condition shows higher dynamic stability as compared to the Newtonian lubricants under the conventional boundary condition. For all considered rheology of lubricants, the dynamic stability of bearing with slip effect is improving by increasing the eccentricity ratio.

High Pressure Rheology of Lubricants (Part 5)

High Pressure Rheology of Lubricants (Part 5)

High Pressure Rheology of Lubricants (Part 8)

High Pressure Rheology of Lubricants (Part 8)

High Pressure Rheology of Lubricants (Part 7)

High Pressure Rheology of Lubricants (Part 7)

Thermal Analysis of Journal bearing with controlled slip/no-slip boundary condition and Non-Newtonian Rheology of lubricant

This paper discusses the combined effect of Non-Newtonian rheology of lubricants and slip boundary condition on the static performance characteristics of finite hydrodynamic journal bearings. A modified JFO model with an adiabatic energy equation has been used for calculating the variation of performance parameters. It has been observed that shear-thinning lubricant with slip effect on partial circumferential region shows a significant percentage of improvement in load-carrying capacity and coefficient of friction. Further, For eccentricity ratio of less than 0.2, these lubricants give maximum tribological performance as compared to Newtonian lubricants under conventional boundary condition.

潤滑油の高圧物性（第5報） ―ファンデルワールス型粘性方程式の導出―

潤滑油の高圧物性（第5報） ―ファンデルワールス型粘性方程式の導出―

High Pressure Rheology of Lubricants (Part 6)

High Pressure Rheology of Lubricants (Part 6)

Rheology of Plastic Lubricants with Additives of Carbon Nanostructures of Various Type

Abstract—Viscosity and the viscosity–temperature dependence are the main criteria for selecting plastic lubricant materials (PLM). The viscoelastic flow of three industrially produced PLM doped with four types of carbon nanostructure (CNS) was assessed. The effect of concentration, type of CNS, and frequency shift (shear and oscillation tests) on this indicator was analyzed. It was shown that the general trend for all the studied systems is a decrease in dynamic viscosity and viscoelastic properties upon the addition of CNS into the basic PLM in the range of shear velocities from 0 to 10 rps and the frequency range from 0.1 to 12 Hz. Shungite carbon nanoparticles have the least effect on the elastic properties of the systems. It was found that the magnitude of the decrease in viscosity of the PLM doped with CNS (additive concentration of 0.5 or 1.0 wt %) depends on the spatial structure of CNS and can be represented by the following sequence: 2D (multilayer oxidized graphene) > 1D (single-walled carbon nanotubes) > 1D (multiwalled carbon nanotubes).

High Pressure Rheology of Lubricants (Part 2)

High Pressure Rheology of Lubricants (Part 2)

High Pressure Rheology of Lubricants (Part 3)

High Pressure Rheology of Lubricants (Part 3)

潤滑油の高圧物性(第1報) ―粘度の圧力，温度，密度関係式の導出―

潤滑油の高圧物性(第1報) ―粘度の圧力，温度，密度関係式の導出―

Linear Stability Analysis of Journal Bearings Lubricated With a Non-Newtonian Rabinowitsch Fluid

AbstractThe linear stability boundaries of journal bearings lubricated with a non-Newtonian fluid have been investigated in this paper. Based on the Rabinowitsch fluid model, a non-Newtonian dynamic Reynolds equation for journal bearings is derived and then applied to analyze the linear dynamic characteristics of short journal bearings. Comparing with the Newtonian-lubricant case, the non-Newtonian rheology of dilatant lubricants provides a larger area of linearly stable region. However, the non-Newtonian properties of pseudo-plastic lubricants results in a reverse trend for the short journal bearing.

Analytical model for predicting friction in line contacts

AbstractThis paper presents the development of an analytical model for the prediction of the friction coefficient in line contacts under thermal elastohydrodynamic lubrication (TEHL). A new theoretical equation is deduced for determining the friction coefficient, taking into account the rheology of common lubricants under TEHL. This approach also considers the heat generated and its penetration into the bulk of the contacting solids. Therefore, the increase in temperature and ensuing variations in the operating conditions are determined.In order to illustrate the use of the new model and verify its accuracy, an experimental stage is performed in a tribological test rig. The predictions of the proposed model are compared with the results obtained in the test rig and other data reported in the literature for diverse lubricants, showing a good agreement in every case. © 2015 The Authors Lubrication Science published by John Wiley & Sons Ltd.