The tribological performance of an artificial hip joint has a particularly strong influence on its success. The principle causes for failure are adverse short- and long-term reactions to wear debris and high frictional torque in the case of poor lubrication that may cause loosening of the implant. Therefore, using experimental and theoretical approaches models have been developed to evaluate lu...

We study the motion of large bubbles in curved channels both semi-analytically using the lubrication approximation and computationally using a finite-volume/fronttracking method. The steady film thickness is governed by the classical Landau– Levich–Derjaguin–Bretherton (LLDB) equation in the low-capillary-number limit but with the boundary conditions modified to account for the channel curvatur...

OBJECTIVE To compare equine synovial fluid (SF) from injured and control joints for cartilage boundary lubrication function; concentrations of the putative boundary lubricant molecules hyaluronan (HA), proteoglycan 4 (PRG4), and surface-active phospholipids (SAPLs); relationships between lubrication function and composition; and lubrication restoration by addition of HA. METHODS Equine SF fro...

The lubrication system of an internal combustion engine serves many purposes. It lubricates moving parts, cools the engine, removes impurities, supports loads, and minimizes friction. The entrapment of air in the lubricating oil is called oil aeration. Oil aeration can be detrimental to internal combustion (IC) engines. This study attempts to determine a means to reduce the level of aeration in...

We review some of the key tribological issues of relevance to motorsport applications. Tribology is the science of friction and wear, and in a high performance engine, friction and wear are controlled by good component design (e.g. the engine and the transmission) and also by the use of high performance lubricants with the correct physical (and chemical) properties, matched to the machine they ...

Thin fluid films can have surprising behavior depending on the boundary conditions enforced, the energy input and the specific Reynolds number of the fluid motion. Here we study the equations of motion for a thin fluid film with a free boundary and its other interface in contact with a solid wall. Although shear dissipation increases for thinner layers and the motion can generally be described ...

A generalized form of Reynolds equation for fluid lubrication has been derived considering the effects of viscosity variation in the film and slip at the bearing surfaces. Various specific cases have been deduced and the concept of multiple-layer lubrication introduced. The higher lubricant viscosity near the bearing surface is beneficial in reducing the coefficient of friction but the effect o...

It is proposed to use elastomeric composites as artificial joint bearing surfaces to increase their fluid film lubrication and therefore reduce the number of failures which have been attributed to wear mechanisms related to frictional forces. The fluid generated between the surfaces supports part of the load and prevents direct contact of the bearing surfaces. In order to obtain optimum elastoh...