Determination of the Critical Length of a Subsurface Crack in a Monobloc R7T Railway Wheel Using FEM Analysis

2010 ◽  
Author(s):  
A. Jafari ◽  
J. Alizadeh K.
Keyword(s):  
Crack Length ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Critical Length ◽  
Fem Analysis ◽  
Rolling Contact ◽  
Subsurface Crack ◽  
Critical Crack ◽  
Critical Crack Length ◽  
Railway Wheels

Based on the endeavors have been made to reduce the wear rate of the railway wheels surfaces, and increase in the axle loads and the velocity of the trains, rolling contact fatigue of the railway wheels is nowadays a considerable damage with regard to the railway wheels. The initiated cracks in the wheels are classified into surface and subsurface ones. The former are usually removed by wear, while the latter propagate gradually until reaching the critical crack length and then suddenly bring about dangerous fractures. So, in any maintenance process of a railway system, it is essential to have the critical crack length as a vital tool to determine the possibility of the critical condition occurrence in the case of identified cracks in wheels. The critical crack length is a residential value and should be determined for any railway systems. So, by using FEM, this paper models an Iranian Railways wheel having the diameter of 920mm, made of R7T material which has a subsurface crack. The wheel is in contact with UIC60 rail. After analysis of this model, rang of stress intensity factor of the crack has been calculated for the different rotation angles. Finally, the critical length of a subsurface crack in conformity with Iranian Railways has been determined based on the fracture mechanics and some approximate relations about mechanical properties. Results show that because of geometrical limitations of the wheel, a subsurface crack can cause the wheel fracture before reaching the critical length.

Observation of Fatigue Fracture on PEEK Shaft against Alumina Bearing’s Ball under One-Point Rolling Contact

2016 ◽  
Vol 878 ◽  
pp. 137-141 ◽  
Author(s):  
Hitonobu Koike ◽  
Genya Yamaguchi ◽  
Koshiro Mizobe ◽  
Yuji Kashima ◽  
Katsuyuki Kida
Keyword(s):  
Fatigue Fracture ◽  
Rolling Contact Fatigue ◽  
Rolling Direction ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Hertzian Contact ◽  
Subsurface Crack ◽  
Mechanical Elements ◽  
The One ◽  
Alumina Ball

Tribological fatigue failure of the machined PEEK shaft was investigated through the one-point type rolling contact fatigue test between a PEEK shaft and an alumina ball, in order to explore fatigue fracture mechanism of frictional parts working at high frequency in various mechanical elements. Due to Hertzian contact of cyclic compressive stress, the subsurface crack occurred within approximately 300 μm depth from thesurface and propagated along the rolling direction. After that, the subsurface crack propagation direction changed toward the surface. The flaking occurred on the raceway of the PEEK shaft when the subsurface crack reached to the PEEK shaft surface.

scholarly journals Influence of the steel grades on rolling contact fatigue of railway wheels

2011 ◽  
Vol 10 ◽  
pp. 2627-2632 ◽  
Author(s):  
A. Langueh ◽  
J-F. Brunel ◽  
E. Charkaluk ◽  
P. Dufrénoy ◽  
F. Demilly
Keyword(s):  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Steel Grades ◽  
Railway Wheels

scholarly journals Effect of Gas Nitriding on Interface Adhesion and Surface Damage of CL60 Railway Wheels under Rolling Contact Conditions

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 911
Author(s):  
Qiang Wu ◽  
Tao Qin ◽  
Mingxue Shen ◽  
Kangjie Rong ◽  
Guangyao Xiong ◽  
...  
Keyword(s):  
Wear Behavior ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Wheel Surface ◽  
Fatigue Wear ◽  
Material Loss ◽  
Surface Protection ◽  
Gas Nitriding ◽  
Railway Wheels

The influence of surface gas nitriding on wheel/rail rolling contact fatigue and wear behavior of CL60 wheel was studied on a new rolling contact fatigue/wear tester (JD-DRCF/M). The failure mechanisms of the wheel/rail surface after the gas nitriding and without gas nitriding on the wheel surface were compared and analyzed. The results show that the wheel with gas nitriding could form a dense and hard white bright layer which was approximately 25 μm thick and a diffusion layer which was approximately 70 μm thick on the wheel surface. Thus, the gas nitriding on the railway wheel not only significantly improved the wear resistance on the surface of the wheel, but also effectively reduced the wear of the rail; the results show that the material loss reduced by 58.05% and 10.77%, respectively. After the wheel surface was subjected to gas nitriding, the adhesive coefficient between the wheel/rail was reduced by 11.7% in dry conditions, and was reduced by 18.4% in water media, but even so, the wheel with gas nitriding still could keep a satisfactory adhesive coefficient between the wheel/rail systems, which can prevent the occurrence of phenomena such as wheel-slip. In short, the gas nitriding on the wheel surface can effectively reduce the wear, and improve the rolling contact fatigue resistance of the wheel/rail system. This study enlarges the application field of gas nitriding and provides a new method for the surface protection of railway wheels in heavy-duty transportation.

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.

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.

Relationships between the fatigue crack growth resistance characteristics of a steel and the tread surface damage of railway wheel

2018 ◽  
Vol 2 (90) ◽  
pp. 49-55 ◽  
Author(s):  
O.P. Ostash ◽  
V.V. Kulyk ◽  
T.M. Lenkovskiy ◽  
Z.A. Duriagina ◽  
V.V. Vira ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Crack Growth Resistance ◽  
Rolling Contact ◽  
Wheel Steel ◽  
Fatigue Crack Growth Resistance ◽  
Railway Wheels

Purpose: The aim of the proposed research is to establish experimentally the relation between damaging of the tread surface of model wheels and the characteristics of fatigue crack growth resistance of wheel steels "KI th, "KII th, "KI fc, "KII fc), depending on its microstructure. Design/methodology/approach: Characteristics of the fatigue crack growth resistance have been determined on the specimens cut out from the hot rolled plate of thickness 10 mm of the steel which is an analogue of railway wheel steels. To obtain different steel microstructures and its strength level, test specimens were quenched (820°C, in oil) and then tempered at 400°C, 500°C, and 600°C for 2 h. The characteristics of Mode I fatigue crack growth resistance of steel were determined on the basis of fatigue macrocrack growth rate diagrams da/dN–"KI, obtained by the standard method on compact specimens with the thickness of 10 mm at a frequency of 10-15 Hz and the stress ratio R = 0.1 of the loading cycle. The characteristics of Mode II fatigue crack growth resistance were determined on the basis of da/dN–"KII diagrams, obtained by authors method on edge notched specimens with the thickness 3.2 mm at a frequency of 10-15 Hz and R = –1 taking account of the crack face friction. The hardness was measured with a TK-2 hardness meter. Zeiss-EVO40XVP scanning electron microscope was used for microstructural investigations. Rolling contact fatigue testing was carried out on the model specimens of a wheel of thickness 8 mm and diameter 40 mm in contact with a rail of length 220 mm, width 8 mm and height 16 mm. Wheels were manufactured form the above-described steel after different treatment modes. Rails were cut out from a head the full-scale rail of hardness 46 HRC. The damaging was assessed by a ratio of the area with gaps formed by pitting and spalling to the general area of the wheel tread surface using a special stand. Findings: The growth of the damage of the tread surface of the model wheels correlates uniquely with the decrease of the cyclic fracture toughness of the wheel steel "KI fc and "KII fc, determined at Mode I and Mode II fracture mechanisms. These characteristics of the wheel steel can be considered as the determining parameter of this process, in contrast to the fatigue thresholds "KI th and "KII th. Research limitations/implications: Investigations were conducted on model wheels that simulate the damage of real railway wheels tread surface. Practical implications: A relationship between the damage of tread surface of railway wheels and the strength level of wheel steels is determined. Originality/value: The damage of the tread surface of the model wheels during the rolling contact fatigue of the pair wheel-rail increases with the growth of the strength (hardness) of the wheel steel, which corresponds to the statistical data of the operation of the real railway wheels.

scholarly journals Effects of sliding on rolling contact fatigue of railway wheels

2012 ◽  
Vol 36 (6) ◽  
pp. 515-525 ◽  
Author(s):  
A. M. G. LANGUEH ◽  
J.-F. BRUNEL ◽  
E. CHARKALUK ◽  
P. DUFRÉNOY ◽  
J.-B. TRITSCH ◽  
...  
Keyword(s):  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Railway Wheels
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