Evaluation of Surface Defects of Wheel and Rail for Korean High-Speed Railway

2010 ◽  
Vol 654-656 ◽  
pp. 2499-2502 ◽  
Author(s):  
Chan Woo Lee ◽  
Seok Jin Kwon
Keyword(s):  
High Speed ◽  
Surface Defects ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Railway Vehicle ◽  
High Speed Railway ◽  
Main Research ◽  
Rail Systems ◽  
Micro Cracks

Wheels of the railway vehicle play the important role for driving train through wheel-rail interaction. Especially wheel profile is one of the most important design factors to rule the running stability and safety of train. Accordingly, the control of rolling contact fatigue-related defects is an ongoing concern for both safety and cost reasons. This process is referred to as ratcheting. Wear of wheel and rail surfaces occur due to a mixture of adhesive, abrasive and corrosive processes. In wheel/rail systems with little wear, such failure is manifested by the appearance of closely spaced micro-cracks. In the present paper, a evaluation of surface defects of wheel and rail for Korean high-speed railway. The main research application is the wheel-rail maintenance of Korea high-speed train.

Rolling Contact Fatigue Damage of High-speed Railway Wheels with Upper Bainite

2021 ◽  
pp. 1-25
Author(s):  
Guanzhen Zhang ◽  
Chunpeng Liu ◽  
Si Wu ◽  
Sa Zhao ◽  
Bin Zhang
Keyword(s):  
Electron Microscopy ◽  
High Speed ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
High Speed Railway ◽  
Matrix Microstructure ◽  
Upper Bainite ◽  
The Right ◽  
Railway Wheels

Abstract This work investigates the effect of abnormal microstructure on rolling contact fatigue (RCF) damage of high-speed railway wheels under service and the formation mechanism of abnormal microstructure by optical microscopy, scanning electron microscopy, transmission electron microscopy, nano indentation and laser-induced break down spectroscopy. Results show that there are large amounts of upper bainite in the wheel tread, which destroyed the uniformity of the microstructures of the wheel matrix. The bainite is composed of ferrite with high density of dislocations and short bar-shaped cementite. The bainite exhibited higher hardness and elasticity but lower plasticity than the matrix microstructure. The incongruity of plastic deformation between upper bainite and matrix microstructures will lead to stress concentration at boundary of the microstructures, thus accelerating the RCF crack initiation and propagation. The formation of upper bainite is caused by carbon segregation. Segregation of carbon element will make the continuous cooling transformation (CCT) curve shift to the right significantly, thus increasing the probability of bainite transformation in segregation zone at higher cooling rate. Therefore, large amounts of upper bainite were formed at wheel tread.

Numerical simulation of rail surface-initiated rolling contact fatigue in the switch panel of railway turnouts

2020 ◽  
pp. 095440972090997
Author(s):  
Xiaochuan Ma ◽  
Ping Wang ◽  
Jingmang Xu ◽  
Rong Chen ◽  
Linya Liu
Keyword(s):  
Friction Coefficient ◽  
Fatigue Damage ◽  
High Speed ◽  
Interaction Analysis ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Control Measures ◽  
High Speed Railway ◽  
Friction Control

Considering the complex characteristics of the track structure in railway turnouts, it is difficult and also expensive to experimentally study rail damages; therefore, numerical methods are an effective alternative. This study presents a numerical method to simulate rail surface-initiated rolling contact fatigue in the switch panel of railway turnouts. This method includes simulation of the vehicle–turnout wheel–rail dynamic interaction, analysis of the wheel–rail multipoint non-Hertzian rolling contact that considers the relative motion between the switch and stock rails, and calculation of the accumulated rail surface-initiated rolling contact fatigue. The accumulated rail surface-initiated rolling contact fatigue after the vehicles passed a turnout switch panel 80 times (the average number of vehicles running on the Chinese high-speed railway lines per day) in the through route with facing move was simulated based on this procedure. The result showed that the maximum surface-initiated rolling contact fatigue damage of the switch rail and the stock rail was 1.57 × 10−2 and 0.62 × 10−2, respectively. Surface-initiated rolling contact fatigue in the switch rail mainly occurred at the gauge angle, and in the stock rail it mainly occurred at the center of the rail. In addition, the influence of track parameters (rail inclination, track gauge, and friction coefficient) is analyzed. The friction coefficient influenced the rail surface-initiated rolling contact fatigue. When the coefficient exceeded 0.3 in particular, the rail rolling contact fatigue damage increased sharply. Hence, suitable friction control measures should be taken during rail maintenance in order to mitigate the rail surface-initiated rolling contact fatigue damage, e.g. by keeping the wheel–rail friction coefficient below 0.3.

A Coupled Multibody Finite Element Model for Investigating Effects of Surface Defects on Rolling Contact Fatigue

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Zamzam Golmohammadi ◽  
Farshid Sadeghi
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Surface Defects ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Internal Stresses ◽  
Fe Model ◽  
Elastic Plastic ◽  
Pile Up

A coupled multibody elastic–plastic finite element (FE) model was developed to investigate the effects of surface defects, such as dents on rolling contact fatigue (RCF). The coupled Voronoi FE model was used to determine the contact pressure acting over the surface defect, internal stresses, damage, etc. In order to determine the shape of a dent and material pile up during the over rolling process, a rigid indenter was pressed against an elastic plastic semi-infinite domain. Continuum damage mechanics (CDM) was used to account for material degradation during RCF. Using CDM, spall initiation and propagation in a line contact was modeled and investigated. A parametric study using the model was performed to examine the effects of dent sharpness, pile up ratio, and applied load on the spall formation and fatigue life. The spall patterns were found to be consistent with experimental observations from the open literature. Moreover, the results demonstrated that the dent shape and sharpness had a significant effect on pressure and thus fatigue life. Higher dent sharpness ratios significantly reduced the fatigue life.

Study of Inner Micro Cracks on Rolling Contact Fatigue of Bearing Steels Using Ultrasonic Nano-Crystalline Surface Modification

2011 ◽  
Vol 462-463 ◽  
pp. 979-984 ◽  
Author(s):  
Chang Soon Lee ◽  
In Shik Cho ◽  
Young Shik Pyoun ◽  
In Gyu Park
Keyword(s):  
Surface Modification ◽  
Rolling Contact Fatigue ◽  
Rolling Direction ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Fatigue Lifetime ◽  
Bearing Steels ◽  
Nano Crystalline ◽  
Micro Cracks ◽  
Crystalline Surface

The purpose of this study is to analyze the effect of ultrasonic nano-crystalline surface modification (UNSM) treatment on rolling contact fatigue (RCF) characteristics of bearing steels. It was found that severe plastic deformation occurred at surface by over 100 µm after UNSM treatment. The micro surface hardness was increased by 18%, and the measured compressive residual stress was as high as -700~-900MPa. The polymet RCF-2 roller type RCF test showed over 2 times longer fatigue lifetime after UNSM treatment under Hertzian contact stress of 425.2kg/mm2 and 8,000 rpm. And SEM study showed a spalling phenomenon at the samples which went through the RCF test after UNSM treatment. Samples before UNSM treatment produced surface initiated spalls and multi shear lips by progressive spalling at the end along the rolling direction, but sub-surface initiated spalls were formed without multi shear lips after UNSM treatment. The spalling occurred at once, and the size and depth of spalls were larger than those before UNSM treatment. And micro cracks were found to form within the spallings after UNSM treatment, and stress distribution at the maximum Herzian shear stress through these micro cracks is thought to improve the fatigue lifetime of bearing materials.

A Possible Mechanism for Rail Dark Spot Defects

1998 ◽  
Vol 120 (2) ◽  
pp. 304-309 ◽  
Author(s):  
M. Kaneta ◽  
K. Matsuda ◽  
K. Murakami ◽  
H. Nishikawa
Keyword(s):  
Fracture Mechanics ◽  
Fatigue Failure ◽  
High Speed ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Traction Force ◽  
Rolling Contact ◽  
Dark Spot ◽  
A Posteriori ◽  
Direction Opposite

Rail dark spot defect, also termed squat failure or shelling, which is a kind of rolling contact fatigue failure and occurs frequently on running surfaces of railway rails carrying high speed traffic, is one of the most dangerous rail failures. The dark spot crack is characterized by a principal crack propagating in the direction of traffic and a second crack growing in the direction opposite to traffic. By using a newly developed two-disk machine, the authors have succeeded in reproducing very similar dark spot cracks to those which appear in actual rails. It is found that the dark spot defects are caused by frequent repetitions of dry and wet runnings, and that the traction force plays an important role for the occurrence of the cracks. The principal crack may occur from a tiny pit formed a posteriori on the contacting surface and after that, the second crack is formed by cracks branched from the extended principal crack. It has also been proved experimentally that water is capable of entering the tip of the crack. Furthermore, a possible mechanism for the dark spot cracking has been proposed on the basis of the fracture mechanics approach.

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