Pueblo, CO, United States
Pueblo, CO, United States

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Tutumluer E.,University of Illinois at Urbana - Champaign | Qian Y.,University of Illinois at Urbana - Champaign | Hashash Y.M.A.,University of Illinois at Urbana - Champaign | Ghaboussi J.,University of Illinois at Urbana - Champaign | Davis D.D.,Inc. TTCI
International Journal of Rail Transportation | Year: 2013

Railroad ballast layer consists of discrete aggregate particles and Discrete Element Method (DEM) is one of the most suitable ways to simulate the deformation behaviour of particulate nature of ballast materials. An aggregate imaging based DEM simulation platform developed at the University of Illinois at Urbana–Champaign (UIUC) can simulate railroad ballast behaviour through the use of polyhedron shaped discrete elements. These ballast elements are created with realistic size and shape properties from image analyses of actual particles using an Aggregate Image Analyzer. The UIUC railroad ballast DEM model was recently put to test for predicting settlement behaviour of full-scale test sections under repeated heavy axle train loading. Field settlement data were collected from the Facility for Accelerated Service Testing (FAST) for Heavy Axle Load (HAL) applications at Transportation Technology Center (TTC) in Pueblo, Colorado, to validate the DEM model. The ballast settlement predictions due to the repeated train loading indicate that the DEM model could predict magnitudes of the field ballast settlements from both early loading cycles and over 90 Million Gross Tons (MGTs) performance trends reasonably accurately. The settlement predictions were sensitive to aggregate shape, gradation and initial compaction condition (density) of the constructed ballast layer. © 2013 Taylor & Francis.


Robles Hernandez F.C.,Inc. TTCI | Cummings S.,Inc. TTCI | Kalay S.,Inc. TTCI | Stone D.,Hunter Holiday Consulting
Wear | Year: 2011

The methodology followed by Transportation Technology Center, Inc., to develop a pearlitic high performance wheel steel (identified as SRI) is described in the first part of this paper. Ideally, this steel will be proposed as high performance wheel steel to the Association of American Railroads (AAR). If successful, the SRI steel will be identified as AAR Class D steel. The second part of the paper provides the results of the mechanical testing of seven high performance wheels (six pearlitic and one bainitic) manufactured by different companies and are compared to the SRI steel. Some of these high performance wheel steels had been tested in heavy haul lines, but had not been tested in the USA heavy haul environment. The results in this paper indicate that the mechanical properties of the SRI steel are superior to those of AAR Class C steel. Vacuum degassing can significantly improve fatigue resistance and is recommended for the SRI steel. The experimental SRI wheels were forged in Brasil at the MWL Brasil facilities. The cleanliness and mechanical properties of the SRI wheel steels compared to the other high performance wheel steels show that among the pearlitic steels, the SRI steel has the highest cleanliness and mechanical properties. © 2010.


Meymand S.Z.,Virginia Polytechnic Institute and State University | Keylin A.,Inc. TTCI | Ahmadian M.,Virginia Polytechnic Institute and State University
Vehicle System Dynamics | Year: 2016

Accurate and efficient contact models for wheel–rail interaction are essential for the study of the dynamic behaviour of a railway vehicle. Assessment of the contact forces and moments, as well as contact geometry provide a fundamental foundation for such tasks as design of braking and traction control systems, prediction of wheel and rail wear, and evaluation of ride safety and comfort. This paper discusses the evolution and the current state of the theories for solving the wheel–rail contact problem for rolling stock. The well-known theories for modelling both normal contact (Hertzian and non-Hertzian) and tangential contact (Kalker's linear theory, FASTSIM, CONTACT, Polach's theory, etc.) are reviewed. The paper discusses the simplifying assumptions for developing these models and compares their functionality. The experimental studies for evaluation of contact models are also reviewed. This paper concludes with discussing open areas in contact mechanics that require further research for developing better models to represent the wheel–rail interaction. © 2016 Taylor & Francis

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