The Influence of Crack Face Friction and Trapped Fluid on Surface Initiated Rolling Contact Fatigue Cracks

1988 ◽  
Vol 110 (4) ◽  
pp. 704-711 ◽  
Author(s):  
A. F. Bower
Keyword(s):  
Crack Growth ◽  
Fatigue Cracks ◽  
Rolling Contact Fatigue ◽  
Fluid Pressure ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Shear Stresses ◽  
Crack Face ◽  
Cyclic Shear ◽  
Mode Ii Crack

A two-dimensional model of a surface initiated rolling contact fatigue crack has been developed. The model takes into account the effects of frictional locking between the faces of the crack, and the influence of fluid pressure acting on the crack faces. The model has been used to investigate three possible mechanisms for propagating the cracks: mode II crack growth due to the cyclic shear stresses caused by repeated rolling contact; crack growth due to fluid forced into the crack by the load; and crack growth due to fluid trapped inside the crack. The predictions of the theory are compared with the behaviour of contact fatigue cracks.

Effect of Lubricant on Surface Rolling Contact Fatigue Cracks

2010 ◽  
Vol 97-101 ◽  
pp. 793-796 ◽  
Author(s):  
Khalil Farhangdoost ◽  
Mohammad Kavoosi
Keyword(s):  
Fatigue Crack ◽  
Fatigue Cracks ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Hertzian Contact ◽  
Element Analysis ◽  
Crack Face ◽  
Hertzian Contact Stress ◽  
Model Of Friction

This study performed the finite element analysis of the cycle of stress intensity factors at the surface initiated rolling contact fatigue crack tip under Hertzian contact stress including an accurate model of friction between the faces of the crack and the effect of fluid inside the crack. A two-dimensional model of a rolling contact fatigue crack has been developed with FRANC-2D software. The model includes the effect of Coulomb friction between the faces of the crack. The fluid in the crack was assumed not only to lubricate the crack faces and reduce the crack face friction coefficient but also to generate a pressure.

Equilibrium of crack growth and wear rates during unlubricated rolling-sliding contact of pearlitic rail steel

2000 ◽  
Vol 214 (2) ◽  
pp. 93-105 ◽  
Author(s):  
D. I. Fletcher ◽  
J. H. Beynon
Keyword(s):  
Steady State ◽  
Crack Growth ◽  
Rail Steel ◽  
Fatigue Cracks ◽  
Rolling Contact Fatigue ◽  
Crack Depth ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Sliding Contact ◽  
Test Machine

It is generally accepted that large rolling contact fatigue cracks in rails do not develop during unlubricated rolling-sliding contact, and damage under these conditions is restricted to wear of the rail steel. However, close examination of a worn rail steel surface reveals the presence of a multitude of wear flakes, the roots of which closely resemble shallow rolling contact fatigue cracks. Experiments have been conducted under unlubricated rolling-sliding conditions to examine the early development of flakes, or cracks, using a laboratory-based, twin-disc test machine to simulate the contact pressure and slip characteristic of the contact between a rail and a locomotive driving wheel. Small defects were found after as few as 125 unlubricated contact cycles. It was found that an equilibrium between crack growth rate and surface wear rate was established after approximately 10 000 cycles, leading to a shallow steady state crack depth. Initial crack growth by ratchetting (accumulation of unidirectional plastic strain until the critical failure strain of the material is reached), followed by shear stress-driven crack growth described by fracture mechanics, was found to be a sequence of mechanisms in qualitative agreement with the observed crack growth and steady state crack depth.

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.

Some comments on stress intensity factor calculation using different mechanisms and procedures for rolling contact fatigue cracks

2009 ◽  
Vol 223 (3) ◽  
pp. 209-221 ◽  
Author(s):  
M Akama ◽  
T Nagashima
Keyword(s):  
Stress Intensity ◽  
Fatigue Cracks ◽  
Rolling Contact Fatigue ◽  
Fluid Pressure ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Intensity Factors ◽  
The Past ◽  
Crack Faces ◽  
Inclined Surface

Recently, attempts have been underway to simulate rolling contact fatigue (RCF) crack growth in the railhead, including also the effect of wear on maintaining the integrity of the rail and saving cost. At this juncture, it is essential to confirm whether the past analyses are adequate and what extent of differences exists when the different mechanisms or numerical procedures are applied to the same conditions in the RCF problem. Therefore, boundary-element analyses of stress intensity factors (SIFs) at the inclined surface crack tip under RCF conditions have been performed. Comparisons were made between SIFs calculated by the present analyses and those done by the numerical procedures of other researchers in the RCF problem. From this study, it was recognized that a special program should be developed to analyse the SIFs when the fluid pressure is taken into account. It was also found out that, for the analyses of SIFs, the iteration procedure with convergence calculation to specify the extent and location of locked, slipped, and separated regions on the crack faces should be used.

527 Effect of crack face friction on surface crack growth in Si_3N_4 under rolling contact fatigue

2001 ◽  
Vol 2001.9 (0) ◽  
pp. 415-416
Author(s):  
Katsuyuki KIDA ◽  
Toshifumi MOTOKI ◽  
Kazuhisa KITAMURA ◽  
Takuto YAMASAKI ◽  
Kouji NAKA ◽  
...  
Keyword(s):  
Crack Growth ◽  
Surface Crack ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Crack Face ◽  
Surface Crack Growth
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