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.

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.

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.

Rolling Contact Fatigue Crack Growth Prediction by the Asperity Point Load Mechanism

2011 ◽  
Vol 488-489 ◽  
pp. 101-104
Author(s):  
Dave Hannes ◽  
B. Alfredsson
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Path ◽  
Fatigue Cracks ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Point Load ◽  
Rolling Contact ◽  
Gear Contact

The crack path and growth life of surface initiated rolling contact fatigue was investigated numerically based on the asperity point load mechanism. Data for the simulation was captured from a gear contact with surface initiated rolling contact fatigue. The evolvement of contact parameters was derived from an FE contact model where the gear contact had been transferred to an equivalent contact of a cylinder against a plane with an asperity. Crack propagation criteria were evaluated with practically identical crack path predictions. It was noted that the trajectory of largest principal stress in the uncracked material could be used for the path prediction. The mode I fracture mechanism was applicable to the investigated rolling contact fatigue cracks. The simulated path agreed with the spall profile both in the entry details as in the overall shape, which suggested that the point load mechanism was valid not only for initiation but also for rolling contact fatigue crack growth. Different equivalent stress intensity factor ranges were used to estimate the fatigue life, which agreed with the life of the investigated gear wheels.

Influence of gear surface roughness on the pitting and micropitting life

2020 ◽  
Vol 234 (24) ◽  
pp. 4953-4961
Author(s):  
Edwin Bergstedt ◽  
Jiachun Lin ◽  
Ulf Olofsson
Keyword(s):  
Surface Roughness ◽  
Gear Tooth ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Tooth Profile ◽  
Rolling Contact ◽  
Roughness Parameters ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Gear Rolling

Pitting and micropitting are the two main gear rolling contact fatigue modes. It is widely accepted that micropitting will lead to pitting; however, the relationship between pitting and micropitting life needs further investigation. In this work, micropitting and pitting tests were performed on an FZG back-to-back test rig using standard FZG PT-C and GF-C gears. The gear tooth profile change due to micropitting and pitting damage was measured in situ in the gearbox using a profilometer after each test. The gear surface roughness parameters were calculated from the measured tooth profile. A Gaussian low pass filter with cut off length [Formula: see text] mm was applied to the measured tooth profile to obtain the waviness. The calculated roughness parameters and the obtained tooth profile with waviness for each test were imported into the KISSsoft software to calculate the contact stress and specific film thickness at the corresponding load stage. Experimental results show that smooth gear surface can reduce or even avoid micropitting damage, but could lead to a reduction in pitting life.

Rolling Contact Fatigue Type Analysis of Rolling Bearing by XRD and TEM

2012 ◽  
Vol 706-709 ◽  
pp. 1679-1684 ◽  
Author(s):  
H. Hidaka ◽  
Kouji Ueda ◽  
N. Mitamura
Keyword(s):  
Film Thickness ◽  
Fatigue Test ◽  
Retained Austenite ◽  
Ball Bearing ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Bearing ◽  
Microstructural Change ◽  
Rolling Contact ◽  
Lubrication Condition

In the rolling bearing, the flaking caused by rolling contact fatigue is classified into two types: surface originated flaking and subsurface originated flaking. It has been recognized that marked microstructural change can occur in subsurface originated flaking due to rolling contact fatigue. But there are few reports in surface originated flaking about microstructural change. In this study, surface originated flaking caused by rolling contact fatigue was investigated based on microstructural change. Thrust ball bearing and radial ball bearing was used for fatigue test. Simulation of dent originated flaking was carried out using the bearing with artificial dent. Another fatigue test subjected to surface originated flaking was done under shortage of oil film thickness lubrication condition. Microstructural change was measured by X-ray Diffractmetry (XRD) and Transmission Electron Microscopy (TEM) during fatigue testing. Microstructure of bearing steel used for fatigue test is consisted of martensite with small amount of retained austenite. XRD measurement reveals that the half peak width of martensite and volume fraction of retained austenite decreasing with increasing testing time, and the amount of decrease in these parameter were small in the surface originated flaking compared with subsurface originated flaking when the specimens were flaking. This suggests that surface originated flaking occurs in spite of mild microstructural change. TEM observation about the surface originated flaking shows plastic flow in the surface layer. Especially, it was confirmed that partial recrystallization occurs in the fatigue test under shortage of oil film thickness lubrication condition. But it was also confirmed that degree of recrystallization is lower in the surface originated flaking than subsurface one, and this reasonably explains XRD result. From these results, it was cleared that recrystallizaiton of martensite is differ in degree but not in kind between surface originated flaking and subsurface originated flaking.

Experimental and Numerical Characterization of a Rail Steel Behavior under Cyclic Contact Stresses

2007 ◽  
Vol 348-349 ◽  
pp. 569-572
Author(s):  
Angelo Mazzù
Keyword(s):  
Crack Formation ◽  
Structural Integrity ◽  
Rail Steel ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Experimental Tests ◽  
Rolling Contact ◽  
Formation Condition ◽  
Numerical Characterization

Wear and rolling contact fatigue interaction in rolling/sliding contact is an important topic in the research on structural integrity of rails and railway wheels. Wear is in competition with rolling contact fatigue, as it removes surface material layers, reducing cracks length and hindering their propagation. Cracks nucleate by accumulation of cyclic unidirectional plastic strain (ratcheting). In this paper a model for ratcheting assessment is discussed and applied to the UIC 900A steel, after a calibration based on experimental results. The experimental tests allow also a characterization of the crack formation condition for this material. By this model, a computer program is developed in order to simulate in a very short time the effect of a large number of load cycles, providing a tool for predicting crack formation and propagation rates.

scholarly journals Rolling contact fatigue in martensitic 100Cr6: Subsurface hardening and crack formation

2014 ◽  
Vol 607 ◽  
pp. 328-333 ◽  
Author(s):  
Jee-Hyun Kang ◽  
R.H. Vegter ◽  
Pedro E.J. Rivera-Díaz-del-Castillo
Keyword(s):  
Crack Formation ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact
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