scholarly journals Rail Integrity Experience on the Washington Metro System

2016 ◽  
Author(s):  
Benjamin Frison ◽  
David Y. Jeong
Keyword(s):  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Surface Damage ◽  
Rolling Contact ◽  
Recent Experience ◽  
Rail Head ◽  
Passenger Rail ◽  
Maintenance Factors ◽  
Rail System ◽  
Rail Service

The Washington Metropolitan Area Transit Authority (WMATA) provides passenger rail service to the nation’s capital. Although the rail system carries only passenger trains, the rail integrity issues that WMATA must manage are similar to those that freight railroads also face. These issues include occurrences of broken rail from internal rail head defects, detection of such defects, and repair of the rail to restore service. Another example is the development of damage on the running surface of the rail, called rolling contact fatigue (RCF). Such surface damage is known to adversely affect the detection of internal rail head defects beneath RCF conditions. While WMATA’s rail integrity issues may be similar to those that freight railroads also encounter, the management of such issues are different, which are also discussed in this paper. This paper describes the recent experience of broken rails on the WMATA rail system. In addition, results from engineering fracture mechanics analyses are presented to help understand how operational, environmental, design, and maintenance factors influence rail failure.

A Subscale Experimental Investigation on the Influence of Sanding on Adhesion and Rolling Contact Fatigue of Wheel/Rail Under Water Condition

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Wanliang Huang ◽  
Xi Cao ◽  
Zefeng Wen ◽  
Wenjian Wang ◽  
Qiyue Liu ◽  
...  
Keyword(s):  
Feed Rate ◽  
Bulk Material ◽  
Fatigue Cracks ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Particle Diameter ◽  
Surface Damage ◽  
Rolling Contact ◽  
Adhesion Coefficient ◽  
Water Condition

With a subscale rolling-sliding apparatus, the objective of this study is to explore the adhesion and rolling contact fatigue characteristics of wheel/rail rollers with sanding under water condition. Sanding improves adhesion coefficient but aggravates the surface damage of wheel and rail materials. With the particle diameter and feed rate increasing, the adhesion coefficient is further improved. However, the surface damage (spalling and pits) becomes severer as well as the surface roughness. Note that pitting is a special damage type when sanding is used to improve the adhesion. Big pits and fatigue cracks appear on subsurface under larger particle diameter and feed rate conditions. Severe cracks initiate from big pits and develop into material to a depth, which results in bulk material breaking.

Experimental and Fracture Mechanics Study of the Pit Formation Mechanism Under Repeated Lubricated Rolling-Sliding Contact: Effects of Reversal of Rotation and Change of the Driving Roller

1997 ◽  
Vol 119 (4) ◽  
pp. 788-796 ◽  
Author(s):  
Y. Murakami ◽  
C. Sakae ◽  
K. Ichimaru ◽  
T. Morita
Keyword(s):  
Fatigue Crack ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Surface Damage ◽  
Fatigue Tests ◽  
Rolling Contact ◽  
Sliding Contact ◽  
Hydraulic Pressure ◽  
Pit Formation ◽  
Original Crack

Five rolling contact fatigue tests, Tests {1}–{5} have been conducted. In Tests {1}–{3}, when a fatigue crack was initiated on the surface of a follower, the test was halted. Then, in Test {1} the rotating direction was reversed. In Test {2} the follower and driver were interchanged, and in Test {3} the test was continued unchanged. In Test {3} the original crack grew to a pit. In Tests {1} and {2} the original crack immediately stopped propagating. In Tests {4} and {5}, mating with a harder roller, a softer roller was used as the follower in Test {4} and as the driver in Test {5}. A typical pit occurred in Test {4}. In Test {5}, surface damage substantially different from a typical pit was generated. Based on these experimental results, a 3-D crack analysis including the effect of frictional force on the contact surface and oil hydraulic pressure on crack surfaces, was conducted to elucidate the mechanisms of pit formation and surface damage in contact fatigue.

Experimental and Theoretical Investigation on Rolling Contact Fatigue of 52100 and M50 Steels Under EHL or Micro-EHL Conditions

1998 ◽  
Vol 120 (2) ◽  
pp. 184-190 ◽  
Author(s):  
D. Ne´lias ◽  
M.-L. Dumont ◽  
F. Couhier ◽  
G. Dudragne ◽  
L. Flamand
Keyword(s):  
Rolling Contact Fatigue ◽  
Large Population ◽  
Contact Fatigue ◽  
Surface Damage ◽  
Rolling Contact ◽  
Surface Finishing ◽  
Micro Cracks ◽  
Pure Rolling ◽  
Surface Distress

The purpose of this investigation is to clarify the role of roughness on rolling contact fatigue. Tests have been carried out on a two-disk machine, for two rolling bearing steels (52100 and M50), two surface roughnesses corresponding to EHL and micro-EHL conditions (two different surface finishing), three normal loadings (1.5, 2.5 and 3.5 GPa), and under pure rolling or rolling plus sliding conditions. No surface damage has been observed up to 50 106 cycles for tests with smooth specimens. Tests with rough specimens have produced a typical surface damage, called here surface distress, made of a large population of asperity-scale micro-cracks and micro-spalls. The paper describes the surface distress observed, such as micro-cracks and micro-spalls. Surface damages obtained are different for tests under pure rolling conditions and tests under rolling plus sliding conditions. Therefore, the role of the friction direction is underlined. A link is made between our experimental observations and calculations that have been carried out using a transient EHL model. The influence of an indent in a line contact, simulating a micro-spall, is studied. Surface pressure and associated sub-surface stress field are analyzed versus the sliding direction.

Influence of Solid Contaminants on the Fatigue Life of Lubricated Machine Elements

2006 ◽  
Vol 220 (5) ◽  
pp. 441-445 ◽  
Author(s):  
F Ville ◽  
S Coulon ◽  
A. A. Lubrecht
Keyword(s):  
Surface Defect ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Surface Damage ◽  
Operating Conditions ◽  
Rolling Contact ◽  
Damage Initiation ◽  
Process Creation ◽  
Rolling Element ◽  
Machine Elements

Solid contamination of lubricants is one of the main causes of premature rolling contact fatigue of machine elements (e.g. rolling element bearings in automotive gearboxes). Understanding the indentation process (creation of surface defect by debris passing through the contact) and the surface damage initiation allows the prediction of the induced risk. This article summarizes the work of the authors and proposes a risk prediction on the basis of operating conditions and dent geometry.

scholarly journals Microstructural Characterisation of Railhead Damage in Insulated Rail Joints

2012 ◽  
Vol 706-709 ◽  
pp. 2937-2942 ◽  
Author(s):  
C. Rathod ◽  
D. Wexler ◽  
T. Chandra ◽  
H. Li
Keyword(s):  
Failure Modes ◽  
Rail Steel ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Surface Damage ◽  
Rolling Contact ◽  
Railway Network ◽  
Position Detection ◽  
Life Problems ◽  
Suggested Keywords

As an integral part the railway network infrastructure, insulated rail joints (IRJs) electrically isolate track segments providing critical feedback to both track signaling and train position detection systems. Because of the discontinuous nature of IRJs, accumulated damage at the railhead is high. Failure modes include plastic flow of metal across joints, bolt and fishplate failures, delamination of insulated material and, as a result of rolling contact fatigue, end post and endpost surface damage. In the current investigation, microstructural changes in the vicinity of endposts of IRJs made from both surface coated and uncoated rail are investigated using techniques of optical and scanning electron microscopy. Damaged IRJs made from pearlitic head hardened rail steel are compared with head hardened rail steel laser coated with martensitic stainless steel, the latter having an increased service life. Problems associated with the surface coating are identified and approaches to further improving IRJ resistance to rolling contact fatigue suggested. Keywords: Insulated rail joints, rail, head hardened, surface coated rail

Prediction of Rolling Contact Fatigue Life in Contaminated Lubricant: Part II—Experimental

1976 ◽  
Vol 98 (3) ◽  
pp. 384-392 ◽  
Author(s):  
T. E. Tallian
Keyword(s):  
Fatigue Life ◽  
Transport Model ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Surface Damage ◽  
Rolling Contact ◽  
Model Case ◽  
Contact Fatigue Life ◽  
General Data ◽  
Present Part

In this second part of a two-part paper, experimental fatigue life data on ball bearings operated under different lubrication conditions are correlated to surface damage densities of life tested ball bearing inner rings, as determined by scanning electron microscopy. In Part I [16], five cases of a mathematical model for the prediction of fatigue life in contaminated bearings were presented. These models are fitted to the experimental data given in the present Part II. The correlation coefficient of experimental L10 life with model Case II predictions, based on observed defect densities, is of the order of 0.99 and highly significant for most test groups. One grease lubricated group requires fitting by model Case III. Predicted life dispersion exponents are too high compared to experiment. General data on lubricant contaminant densities show a sufficiency of particles to cause the observed surface damage, but tend to overpredict damage on the basis of the simple particle transport model used. The principal usefulness of the model in its present form is as a tool for the interpretation of the influence on fatigue life of surface damage acquired in service.

Detrimental Effects of Debris Dents on Rolling Contact Fatigue

1999 ◽  
Vol 122 (1) ◽  
pp. 55-64 ◽  
Author(s):  
D. Ne´lias ◽  
F. Ville
Keyword(s):  
Numerical Simulations ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Surface Damage ◽  
Rolling Bearing ◽  
Initiation Site ◽  
Solid Particles ◽  
Rolling Contact ◽  
Bearing Failures ◽  
Ehl Contact

Debris dents produced by solid particles in suspension in oil or grease when they travel through an EHL contact may be at the origin of rolling bearing failures. A summary of an experimental investigation carried out to identify (i) the particle entry ratio, (ii) the mechanisms of particle fragmentation or deformation, (iii) the resulting indentation features, and (iv) the initiation site of subsequent surface damage is presented first. Afterwards, numerical simulations of a dent moving through an EHL contact are performed. A critical slide-to-roll ratio is found. Results of our numerical simulations are analyzed and discussed in relation to the concept of infinite life for rolling bearing applications. [S0742-4787(00)00901-2]

Sign in / Sign up

Export Citation Format

Share Document