The paper describes results obtained from the micro-elastohydrodynamic lubrication (micro-EHL) modeling of gear tooth contacts used in micropitting tests together with a contact fatigue and damage accumulation analysis surfaces involved. Tooth surface profiles were acquired pairs helical test gears micro-EHL simulations performed corresponding to that actually came into during meshing cycle. Plane strain shows predicted is concentrated close this supports view arises at asperity level. A...

Micropitting is a form of surface fatigue damage that happens at the roughness scale in lubricated contacts commonly used machine elements, such as gears and bearings. It occurs where specific film thickness (ratio smooth to composite roughness) sufficiently low for operate mixed lubrication regime, load part carried by direct asperity contacts. currently seen greater issue gear designers than regular pitting failure latter can be avoided control steel cleanliness. This paper describes...

This article presents the results of a transient elastohydrodynamic analysis conditions at contact two pairs helical gears operating with different gear ratios. The effects variation in geometry, kinematics, and tooth loading during meshing cycle are taken into account together both tip relief axial crowning profile modifications. compared analyses under corresponding steady-state for point equivalent line models. comparisons show that, away from ends lines, can be used effectively to assess...

The paper presents the theoretical basis for modelling contact conditions and elastohydrodynamic lubrication (EHL) of worm gears, results which are presented in Part 2. asymmetric elongated that typifies gears is non-Hertzian treated using a novel three-dimensional elastic simulation technique. kinematic at EHL such surfaces have slide-roll ratio equal to almost 2, sliding direction varies over area. These considerations require non-Newtonian, thermal analysis, appropriate form Reynolds...

The paper describes the application of a full non-Newtonian, thermal elastohydrodynamic lubrication (EHL) model for prediction film thickness and viscous traction force in special high speed rolling rig. primary objective work was to identify suitable lubricant rheological that would describe behavior practical EHL drive contacts over their operating range. Experiments were carried out on contact rig at temperatures 60, 90, 120°C loads giving maximum Hertzian pressures 1, 2, 3 GPa....

The article describes a numerical model for the analysis of elastohydrodynamic lubrication under conditions in which nominal lubricant film thickness is small compared to roughness present on surfaces (lambda ratio less than unity). These occur most types gear tooth contacts and many other heavily loaded machine elements. In these situations, occurs at asperity level (micro-elastohydrodynamic lubrication), extreme cases ‘mixed’ behaviour momentary solid between take place. both...

Worm gears used for power transmission commonly consist of a steel worm running against bronze or phosphor wheel. The wheel teeth are usually manufactured using an ‘oversize’ hob so that the initial elastic contact between is in form ellipse with lubricant entrainment predominantly major axis direction. As result this unfavourable geometry, film generated and relatively thin. kinematic configuration close to simple sliding as velocity tooth surface relative nominal point very low comparison...

This paper explores the possible effects of residual stress fields resulting from plastic deformation real rough surface asperities on subsequent fatigue. A finite element model for elastic-plastic contact surfaces using profiles taken unrun test disks is used to obtain fields. These stresses are then added elastic distribution obtained an elastohydrodynamic analysis see fatigue damage and life at scale roughness asperities. For current paper, Micro-EHL simulations were carried out modelling...

The paper is concerned with prediction of elastic contact and elastohydrodynamic film thickness in worm gears. Using the undeformed geometry gap between gear teeth a three-dimensional simulation technique has been developed for calculation true area under load relative to wheel surfaces. A parallel investigation lubrication effects carried out using special non-Newtonian, thermal solver which takes account nonsymmetrical spin aspects contacts. An interesting feature results obtained...

Abstract The paper presents the results of a thermal analysis set disk experiments carried out by Patching et al. to investigate scuffing. used crowned steel disks at 76-mm centers with maximum Hertzian contact pressures up 1.7 GPa. Experimental measurements friction were as basis for and their associated support shafts. Temperatures measured embedded thermocouples 3.2 mm below running tracks determine heat partition between faster slower in order match experimental calculated temperatures....

The paper presents the results of modelling contact and elastohydrodynamic lubrication (EHL) effects between teeth worm gears. A number different practical gear designs have been studied covering a wide range sizes potential applications, from small instrument drives to high power units. All are popular ZI type, in which is an involute helicoid, with deliberate mismatch tooth conformity order avoid damaging edge contact. cover loaded analysis (‘loaded TCA’) under dry conditions, predicted...

Reducing frictional losses in response to the energy agenda will require use of less viscous lubricants causing hydrodynamically-lubricated bearings operate with thinner films leading "mixed lubrication" conditions which a degree direct interaction occurs between surfaces protected only by boundary tribofilms. The paper considers consequences and mixed lubrication for concentrated contacts such as those occurring teeth power transmission gears rolling element bearings. Surface fatigue...

This article presents the results of a series thermal elastohydrodynamic lubrication (EHL) analyses set disc experiments carried out by Patching et al. The authors have previously calculated heat partition at each load stage fromthe experimental data, and present work seeks to compare developed in EHL analysis lubricant film with that from experiments. These show depends on non-Newtonian formulation used. Only when dissipation takes place wall slip occurring faster moving surface do approach...

Abstract The article is concerned with thermal elastohydrodynamic lubrication (TEHL) modeling of rolling/sliding contacts and in particular relating the results such models to experiments. Two kinds lubricated contact experiments are considered: (i) traction where overall frictional resistance motion at TEHL measured (ii) heat partition where, addition resistance, temperature distribution contacting components flux into individual determined. discusses problem choosing an accurate...

The paper presents numerical solutions obtained for a wide range of elliptical elastohydrodynamic lubrication (EHL) problems. conditions considered encompass relative principal radii curvature ratios from 20:1 with entrainment in the minor axis direction, to 50:1 major direction. problems derive investigations practical machine elements where width contact (perpendicular entrainment) is limited by extent metal surfaces on either side. Two sets results have been obtained: one lubricated...

The paper describes results obtained from the micro-elastohydrodynamic lubrication (micro-EHL) modelling of gear tooth contacts used in micropitting tests together with contact fatigue and damage accumulation analysis surfaces involved. Tooth surface profiles were acquired pairs helical test gears micro-EHL simulations performed corresponding to that actually came into during meshing cycle. Fatigue shows predicted is concentrated close this strongly suggests arises at asperity level.