Studying the Effect of Tangential Forces on Rolling Contact Fatigue in Rails Considering Microstructure

2019 ◽  
Author(s):  
Mohamad Ghodrati ◽  
Mehdi Ahmadian ◽  
Reza Mirzaeifar
Keyword(s):  
Rolling Contact Fatigue ◽  
Three Dimensional ◽  
Contact Fatigue ◽  
Material Model ◽  
Element Model ◽  
Rolling Contact ◽  
Traction Forces ◽  
Steel Microstructure ◽  
Initiation And Propagation ◽  
Tangential Forces

In this paper, the micro-mechanical mechanisms behind the initiation and propagation of rolling contact fatigue (RCF) damages caused by the large traction forces are investigated. This study provides a three-dimensional (3D) model for studying the rolling contact fatigue in rails. Since rolling contact fatigue is highly dependent on the rail’s steel microstructure behavior, a proper 3D approach to capture the microstructure- and orientation-dependent mechanical behavior is required. A precise material model known as crystal plasticity is used for this purpose. Additionally, a cohesive zone approach is implemented to capture the crack initiation and propagation at the grain boundaries. Using the 3D finite element model which is developed for this study, we evaluate the effect of various parameters such as traction forces along the rail, and also the normal forces on the RCF response. The results reveal that the RCF cracks initiate slightly below the rail surface. These cracks start propagating toward the rail surface when the contact force is applied in repeated load cycles. The results also indicate that the depth at which RCF initiates depends on the ratio between the longitudinal traction forces and the normal loads. With larger traction forces, the cracks initiate closer, or at the rail surface, whereas larger normal loads promote the cracks initiation beneath the surface.

Initiation and propagation of case crushing cracks in rolling contact fatigue

Wear ◽  
1988 ◽  
Vol 122 (1) ◽  
pp. 33-43 ◽  
Author(s):  
Xiaogang Leng ◽  
Qing Chen ◽  
Eryu Shao
Keyword(s):  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Initiation And Propagation

scholarly journals Observation of Flaking Process in Rolling Contact Fatigue by Laminography Using Ultra-bright Synchrotron Radiation

2018 ◽  
Vol 165 ◽  
pp. 11002
Author(s):  
Yoshikazu Nakai ◽  
Daiki Shiozawa ◽  
Shoichi Kikuch ◽  
Hitoshi Saito ◽  
Takashi Nishina ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Crack Initiation ◽  
Rolling Contact Fatigue ◽  
Rolling Direction ◽  
Contact Fatigue ◽  
Critical Length ◽  
Rolling Contact ◽  
Crack Initiation And Propagation ◽  
Initiation And Propagation ◽  
Damage Process

The flaking failure in rolling contact fatigue (RCF) results from crack initiation and propagation has been believed to originate from non-metallic inclusions located beneath the surface. With conventional microscopies, however, damage process in the internal region of materials could not be observed, then RCF crack initiation and propagation behaviours were observed by using synchrotron radiation computed laminography (SRCL) in the brightest synchrotron facility in Japan, and the effect of the inclusion orientation on the RCF property was examined. In our previous studies, crack initiation and propagation behaviours caused by extended MnS inclusions distributed in depth or transverse (width) direction was observed by the SRCL. In the present study, the fracture mechanism under RCF was discussed on specimens with MnS inclusions distributed in the rolling direction. As a result, vertical cracks were initiated on the surface, parallel to the ball-rolling direction in specimens. The crack propagation direction was then changed perpendicular to the rolling direction. Thereafter, similar with our previous studies, vertical cracks caused the horizontal cracks beneath the surface, when the vertical cracks reached to a critical length. The ratio of the vertical crack initiation life to the flaking life was higher than specimens with other inclusion orientation.

Material Response to Rolling Contact Loading

1985 ◽  
Vol 107 (3) ◽  
pp. 359-364 ◽  
Author(s):  
A. P. Voskamp
Keyword(s):  
Rolling Contact Fatigue ◽  
Three Dimensional ◽  
Contact Fatigue ◽  
Load Cycle ◽  
Rolling Contact ◽  
Hertzian Contact ◽  
Microplastic Deformation ◽  
Contact Loading ◽  
Material Response ◽  
Deep Groove

The material response to rolling contact loading has been analyzed using quantitative X-ray diffraction methods. This has led to the discovery of preferred crystalline orientation in very narrow subsurface regions of endurance-tested 6309 deep groove ball bearing inner rings. The high hydrostatic pressure field, derived from the load-induced three-dimensional stress field in each Hertzian contact load cycle, allows substantial microplastic deformation to be accommodated in the subsurface layers. This microplastic deformation is accompanied by transformation of retained austenite, decay of martensite and the development of texture and residual stresses, one of which is a subsurface tensile stress in a direction normal to the surface. Both the preferred orientation and the tensile residual stress allow for crack propagation parallel to the rolling contact surface. Based on these findings, an outline of a qualitative model for rolling contact fatigue is presented.

scholarly journals The Influence of Wheel/Rail Contact Conditions on the Microstructure and Hardness of Railway Wheels

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Paul Molyneux-Berry ◽  
Claire Davis ◽  
Adam Bevan
Keyword(s):  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Dynamic Simulations ◽  
Near Surface ◽  
Wheel Rim ◽  
Ferrite Fraction ◽  
Proeutectoid Ferrite ◽  
Tangential Forces ◽  
Railway Wheels

The susceptibility of railway wheels to wear and rolling contact fatigue damage is influenced by the properties of the wheel material. These are influenced by the steel composition, wheel manufacturing process, and thermal and mechanical loading during operation. The in-service properties therefore vary with depth below the surface and with position across the wheel tread. This paper discusses the stress history at the wheel/rail contact (derived from dynamic simulations) and observed variations in hardness and microstructure. It is shown that the hardness of an “in-service” wheel rim varies significantly, with three distinct effects. The underlying hardness trend with depth can be related to microstructural changes during manufacturing (proeutectoid ferrite fraction and pearlite lamellae spacing). The near-surface layer exhibits plastic flow and microstructural shear, especially in regions which experience high tangential forces when curving, with consequentially higher hardness values. Between 1 mm and 7 mm depth, the wheel/rail contacts cause stresses exceeding the material yield stress, leading to work hardening, without a macroscopic change in microstructure. These changes in material properties through the depth of the wheel rim would tend to increase the likelihood of crack initiation on wheels toward the end of their life. This correlates with observations from several train fleets.

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