Theoretical and experimental investigation of wear during coupling in internal gears coated with various polymeric coating materials was performed in this study. In the theoretical part of the study, Archards’ wear formulation was adapted to internal gears and wear behavior in various conditions was determined. Moreover, a fatigue and wear testing apparatus having similar working principle with...

The transition from boundary lubrication to fully hydrodynamic lubrication is investigated for air-lubricated slider bearings using the electrical resistance method. Intermittent contacts are shown to exist even under conditions for which the numerical solution of the Reynolds equation or white light interferometry predicts steady state spacings in the spacing region from 0.125 to 0.25 pm. The ...

In situ lateral force microscopy (LFM) and X-ray photoelectron spectroscopy (XPS) were used to probe the lubrication behavior of an aqueous solution of poly(oxyethylene)-poly(oxypropylene)-poly(oxyethylene) (PEO-PPO-PEO) symmetric triblock copolymer on thin films of polypropylene (PP), polyethylene (PE), and cellulose. LFM experiments were carried out while the substrates were immersed in water...

In high speed rotating machines such as turbines and generators, vibrations of a rotating shaft often hinder the smooth operation of the machine or even cause failure. Oil whip is one of such vibrations due to oil film action of journal bearing. Its mechanism and preventive method is explained and proposed in this paper. Further theoretical and experimental analyses are made for considering hea...

Articular cartilage is a highly efficacious water-based tribological system that is optimized to provide low friction and wear protection at both low and high loads (pressures) and sliding velocities that must last over a lifetime. Although many different lubrication mechanisms have been proposed, it is becoming increasingly apparent that the tribological performance of cartilage cannot be attr...

The condition of lubricating oil used in automotive and industrial gearboxes must be controlled in order to guarantee optimum performance and prevent damage to machinery parts. In normal practice, this is done by regular oil change intervals and routine laboratory analysis, both of which involve considerable operating costs. In this paper, we present a compact and robust optical sensor that can...

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...