On the formation and damage mechanism of rolling contact fatigue surface cracks of wheel/rail under the dry condition

Wear ◽  
2018 ◽  
Vol 400-401 ◽  
pp. 62-73 ◽  
Author(s):  
Y.B. Huang ◽  
L.B. Shi ◽  
X.J. Zhao ◽  
Z.B. Cai ◽  
Q.Y. Liu ◽  
...  
Author(s):  
Guillermo E Morales-Espejel ◽  
Antonio Gabelli

The effects of kinematic sliding on rolling contact fatigue life have been discussed in many occasions, often with some disregard of the fundamental principles of tribology. In this paper, the authors’ intention is to discuss this issue with a perspective as objective as possible and performing a study on factual and known scientific knowledge, applying tribology modelling and methods. The effects of kinematic sliding of Hertzian contacts are studied from three different standpoints: (1) by analysing the combination of sliding speed and contact pressure giving rise to seizure, that is high instantaneous contact temperatures leading to film collapse, (2) by assessing the possible effects of sliding to surface traction and fatigue, (3) by discussing other possible effects of sliding in heavily loaded lubricated contacts as the concurrent damage mechanism caused by wear and rolling contact fatigue. Throughout the paper, different numerical models are presented and discussed alongside with some experimental data. This approach provides a comprehensive assessment of the various phenomena related to the kinematic sliding of rolling bearings. The different mechanisms involved and the interaction of sliding with the elastohydrodynamic lubricant film, frictional stress, wear and fatigue are discussed, and their significance to the performance of the bearing is qualified.


Author(s):  
A. W. Warren ◽  
Y. B. Guo

The fundamental knowledge of fatigue damage mechanism is necessary for understanding manufacturing process effects. However, the artificial defects on the test samples in traditional fatigue tests will change the surface integrity and therefore may not reflect the nature of fatigue damage. This paper studies the fatigue damage resulting from real-life rolling contact tests and finite element analysis of AISI 52100 steel and identifies the possible mechanisms for fatigue failure in the presence of process induced surface integrity. Rolling contact fatigue damage was real-time monitored using an acoustic emission (AE) sensor. Surface and subsurface fatigue damage of the samples was then characterized using optical and scanning electron microscopy (SEM) and surface profiling. The results suggest that shear stress induced Mode II crack is the dominant fatigue mechanism. Two types of subsurface cracks were observed: main cracks that propagate parallel to the surface due to subsurface shear stress induced fracture/debonding of inclusions or second phase particles. Shear stress induced surface cracks propagate at shallow angles (∼35°) from the surface. Branching cracks eventually form and connect the main crack to surface. The formation of main cracks and surface cracks may be parallel processes, and spalling occurs as a combined effect of the main, surface, and branching cracks. The relationship between AE signals and fatigue damage was been established.


2007 ◽  
Vol 353-358 ◽  
pp. 254-257
Author(s):  
Guan Chen ◽  
Hong Ping Zhao ◽  
Shao Hua Ji ◽  
Xi Qiao Feng ◽  
Hui Ji Shi

Rolling contact fatigue (RCF) cracks initiated from surface and subsurface defects are typical failure modes of bearing systems. In this paper, the effects of surface defects on RCF behavior of M50NiL and M50 steels were studied experimentally. Artificial dents were introduced on the rolling surface by using Rockwell hardness tester. The influences of dent shape and dent shoulders were examined by thrust-type RCF tests. Surface cracks initiation, propagation and spalling were monitored by scanning electron microscope (SEM) observation. The results showed that artificial dents reduce RCF lives of M50NiL and M50 steels with mineral oil lubrication. The fatigue failure initiates at the surface defect with the effects of dent shape and dent shoulder. M50NiL steel has higher contact fatigue resistance than M50. The features of surface and sub-surface cracks propagation during RCF tests were also observed.


2012 ◽  
Vol 566 ◽  
pp. 197-202 ◽  
Author(s):  
Shunsuke Oyama ◽  
Katsuyuki Kida ◽  
Edson Costa Santos ◽  
Hitonobu Koike ◽  
Takashi Honda ◽  
...  

The behavior of surface cracks in PEEK thrust bearings under rolling contact fatigue (RCF) was investigated. Eight small holes were introduced along the bottom race surface, and RCF tests underwater using different loads were carried out. The cracks growing from the holes were observed by using a microscope. It was found that the surface cracks could not be explained by Hertzian crack theory or the ‘wedge effect’ models. This indicates that the standard theories cannot be generally applied to investigation of PEEK bearings working under RCF in water.


2019 ◽  
Vol 264 ◽  
pp. 01004
Author(s):  
Hitonobu KOIKE ◽  
Genya YAMAGUCHI ◽  
Koshiro MIZOBE ◽  
Katsuyuki KIDA

The growth of flaking as tribological fatigue failure in PEEK was investigated through the one-point type rolling contact fatigue test between a machined PEEK polymer shaft and an alumina bearing's ball. Due to Hertzian contact of cyclic compressive stress, the subsurface fatigue cracks in the PEEK shaft propagated in rolling and axial directions. When the rolling fatigue life of the PEEK shaft reached 106 fatigue cycles, many narrow angled cracks occurred in the near-surface of the rolling track without flaking. On the other hand, when the flaking ocuurred on the PEEK shaft before 106 fatigue cycles, semicircular surface and subsurface crack propagations were observed. From these observations, it was found that micro-flaking occurred due to the linkages between subsurface and surface cracks. Flakingdeveloped due to the accumulation of these micro-flakings.


2012 ◽  
Vol 2012 (0) ◽  
pp. 15-16
Author(s):  
Shunsuke Oyama ◽  
Katsuyuki Kida ◽  
Edson Costa Santos ◽  
Hitonobu Koike ◽  
Takashi Honda ◽  
...  

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