Lubrication of mechanical systems using water instead of conventional oil lubricants is extremely attractive from the view of resource conservation and environmental protection. However, insufficient film thickness of water due to low viscosity and chemical reaction of water with metallic materials have been a great obstacle in utilization of water as an effective lubricant. Herein, the frictio...

The tribological performance of artificial hip joints is a critical issue for their success, because adverse tissue reaction to wear debris causes loosening and failure. Many studies on wear and lubrication of hip prostheses have been published in the last 10 years, mostly on experimental tests. Theoretical/ numerical models have been proposed for investigating geometrical and material paramete...

Rarefied gas flows in thin film slider bearings are studied in a wide range of Knudsen numbers (Kn) at low Mach number (Ma) with the objective of developing simple physics-based semi-analytical models. A recently developed modified slip boundary condition for steady plane Couette flows and a generalized high-order velocity slip boundary condition, developed and validated earlier for pressure-dr...

In the paper a comprehensive model of a piston ring pack motion on an oil film has been presented. The local oil film thickness can be compared to height of the combined roughness of sliding surfaces of piston rings and cylinder liner. Equations describing the mixed lubrication problem based on the empirical mathematical model formulated in works of Patir, Cheng and Greenwood, Tripp have been c...

N anoconfined fluids — that is, fluids confined between surfaces separated by nanometers — play important roles in many natural and man-made processes and products. One example is hard disk drive lubrication where, as data density has increased exponentially, the distance between the read head and rotating platen has been exponentially decreasing for several decades. This distance is now at 10–...

An analytical treatment for the sedimentation rate of disordered suspensions is presented in the context of a resistance problem. From the calculation it is confirmed that the lubrication effect is important in contrast to the suggestion by Brady and Durlofsky (Phys.Fluids 31, 717 (1988)). The calculated sedimentation rate agrees well with the experimental results in all range of the volume fra...

The purpose of this research paper is to examine the tribological characteristics and issues related to journal bearings under boundary and mixed lubrication conditions during shaft startup, shutdown, and low speeds. The key issues and problems related to journal bearings, most notably wear, are discussed as well as the subsequent issues created in the field. The mechanical analysis of the load...

A lubrication model describes the dynamics of a thin layer of fluid spreading over a solid substrate. But to make forecasts we need to supply correct initial conditions to the model. Remarkably, the initial fluid thickness is not the correct initial thickness for the lubrication model. Theory recently developed in [12, 14] provides the correct projection of initial conditions onto a model of a ...

Lubrication flows appear in many applications in engineering, biophysics, and in nature. Separation of surfaces and minimisation of friction and wear is achieved when the lubrication fluid builds up a lift force. In this paper we analyse soft lubricated contacts by treating the solid walls as viscoelastic: soft materials are typically not purely elastic, but dissipate energy under dynamical loa...