Occurrence of High Pressure Spike in Unidirectional Start–Stop–Start Point Contacts

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
P. Sperka ◽  
J. Wang ◽  
I. Krupka ◽  
M. Hartl ◽  
M. Kaneta
Keyword(s):  
High Pressure ◽  
Film Thickness ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Elastohydrodynamic Lubrication ◽  
Rolling Contact ◽  
Point Contacts ◽  
Pressure Distributions ◽  
Machine Element ◽  
Pressure Spike

The transient film thickness and pressure distributions in point elastohydrodynamic lubrication (EHL) contacts during start–stop–start motion are discussed based on experimental and numerical analyses. When the machine element starts to move after the stopping, where the oil is entrapped between two surfaces, the pressure at the exit area increases very much. The pressure increase depends markedly on the overall film thickness before the stopping of the motion, but is hardly controlled by the acceleration after the stopping. It can be considered that this phenomenon affects the rolling contact fatigue damage.

A Coupled Approach for Modelling Rolling Contact Fatigue Cracks Under Elastohydrodynamic Lubrication

2009 ◽  
Author(s):  
R. Balcombe ◽  
M. T. Fowell ◽  
A. V. Olver ◽  
D. Dini
Keyword(s):  
Fluid Flow ◽  
Elastic Deformation ◽  
Contact Area ◽  
Fatigue Cracks ◽  
Moving Load ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Elastohydrodynamic Lubrication ◽  
Rolling Contact ◽  
Fluid Solid Interaction

In this paper we present a coupled method for modelling fluid-solid interaction within a crack generated in rolling contact fatigue (RCF) in the presence of lubrication. The technique describes the fluid flow in the contact area and within the crack and explores how this affects the elastic deformation of the solid while the moving load traverses the cracked region. It is argued that this approach sheds light on the instantaneous response of the system, therefore providing a more physically-accurate description of the phenomenon under investigation.

An Approach for the Gear Rolling Contact Fatigue Acceleration

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Sheng Li ◽  
Jeremy J. Wagner
Keyword(s):  
Film Thickness ◽  
Crack Formation ◽  
Crack Nucleation ◽  
Rotational Velocity ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Time Period ◽  
Gear Contact ◽  
Gear Rolling

This study proposes an approach for the acceleration of the experimental gear rolling contact fatigue (RCF) crack formation. By increasing the rotational velocity of a gear pair, the RCF experimental time period is reduced. However, the film thickness is increased to improve the fatigue performance, to counteract which it is proposed to raise the lubricant temperature to reduce the film thickness. A physics-based gear contact fatigue model is used to quantify and offset the effects of the rotational velocity and the lubricant temperature on the crack nucleation.

Prediction of Traction and Microgeometry Effects on Rolling Contact Fatigue Life

1978 ◽  
Vol 100 (2) ◽  
pp. 156-165 ◽  
Author(s):  
T. E. Tallian ◽  
Y. P. Chiu ◽  
E. Van Amerongen
Keyword(s):  
Shear Stress ◽  
Film Thickness ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Shear Stresses ◽  
Deformation Bands ◽  
Hazard Functions ◽  
Stress Region ◽  
Surface Distress

A refined mathematical model for the prediction of rolling contact fatigue is presented. It analyzes the effect of frictional traction in the contact surface, and of surface asperity slope, on the failure hazard functions applicable to surface and subsurface originated spalls. Major effects of traction on life arise from three sources: (a) increased surface distress micropitting; (b) increased microscopic shear stresses beneath surface furrows; (c) greatly increased macroscopic shear stresses in the zone relatively free from shear-stress which exists, in the absence of traction, between the asperity stress region and the Hertzian shear stress region. The major effect of steeper asperity slopes is to increase surface distress micropitting. A strong effect of traction on the angular orientation of the Hertz stress field is used to correlate experimentally observed changes in the Martin angle of orientation of deformation bands. The correlation permits calculation of the variation in the effective traction coefficient as a function of film thickness/roughness ratio. The traction coefficients obtained are then used as input to numerical life prediction. Satisfactory agreement is obtained between theory and experiment in predicting the life of seven groups of fatigue tested ball bearings with different surface roughness, run at different film thickness/roughness ratios.

Crown Drop Effects on the Needle Roller Bearing Life in Oscillatory

2013 ◽  
Vol 740 ◽  
pp. 295-299
Author(s):  
Xiao Yang Chen ◽  
Xue Jin Shen
Keyword(s):  
High Pressure ◽  
Pressure Distribution ◽  
Rolling Contact Fatigue ◽  
Roller Bearing ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Bearing Life ◽  
Comparison Results ◽  
Pressure Concentration ◽  
Fatigue Experiment

In this paper, the effects of chamfer dimension at the Lundbergs profile needle roller end and the grinding undercut of raceway on the pressure distribution, which are used in the oscillatory applications, are discussed. The frame of numerical method for the crown drop evaluation considered these two effects is presented, which makes it possible to profile the needle rollers axially until the longitudinal pressure distribution is neither any edge effects nor high-pressure concentration at the center part of contacts. And the crown drop designed by this method is larger than that by Lundbergs theory. The comparison results of accelerated rolling contact fatigue experiment show that the width of grinding undercut and radius of the chamfer must be considered in determining the crown drop of the needle rollers.

scholarly journals The Role of Elastohydrodynamic Lubrication in Rolling-Contact Fatigue

1963 ◽  
Vol 85 (3) ◽  
pp. 439-447 ◽  
Author(s):  
E. V. Zaretsky ◽  
L. B. Sibley ◽  
W. J. Anderson
Keyword(s):  
Fatigue Life ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Elastohydrodynamic Lubrication ◽  
Rolling Contact ◽  
Contact Fatigue Life ◽  
Steel Balls ◽  
Thickness Measurements ◽  
Ball Test

The five-ball fatigue tester was used to determine the rolling-contact fatigue life of 1/2-inch-diameter M-1 steel balls with four lubricants at 300 deg F. Film thickness measurements were made with the rolling-contact disk machine under simulated five-ball test conditions. Under certain conditions, elastohydrodynamic lubrication was found to exist at initial maximum Hertz stress levels up to 800,000 psi. There appears to be a correlation among the following variables: Plastically deformed profile radius of the ball specimen at ambient temperature; lubricant type; and rolling-contact fatigue. No correlation was found between contact temperature obtained with different lubricants and fatigue life.

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