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Research Papers

Accurate Representation of the Rail Geometry for Multibody System Applications

[+] Author and Article Information
Brian Marquis

 Volpe National Transportation Systems Center, Kendall Square, Cambridge, MA 02142brian.marquis@dot.gov

Khaled E. Zaazaa

 ENSCO, Inc., 5400 Port Royal Road, Springfield, VA 22151zaazaa.khaled@ensco.com

Tariq Sinokrot

Department of Mechanical Engineering, University of Illinois at Chicago, 842 West Taylor Street, Chicago, IL 60607-7022tsinok2@uic.edu

Ahmed A. Shabana

Department of Mechanical Engineering, University of Illinois at Chicago, 842 West Taylor Street, Chicago, IL 60607-7022shabana@uic.edu

J. Comput. Nonlinear Dynam 5(1), 011003 (Nov 12, 2009) (11 pages) doi:10.1115/1.4000254 History: Received June 19, 2008; Revised January 29, 2009; Published November 12, 2009; Online November 12, 2009

The objective of this study is to examine the geometric description of the spiral sections of railway track systems, in order to correctly define the relationship between the geometry of the right and left rails. The geometry of the space curves that define the rails are expressed in terms of the geometry of the space curve that defines the track center curve. Industry inputs such as the horizontal curvature, grade, and superelevation are used to define the track centerline space curve in terms of Euler angles. The analysis presented in this study shows that, in the general case of a spiral, the profile frames of the right and left rails that have zero yaw angles with respect to the track frame have different orientations. As a consequence, the longitudinal tangential creep forces acting on the right and left wheels, in the case of zero yaw angle, are not in the same direction. Nonetheless, the orientation difference between the profile frames of the right and left rails can be defined in terms of a single pitch angle. In the case of small bank angle that defines the superelevation of the track, one can show that this angle directly contributes to the track elevation. The results obtained in this study also show that the right and left rail longitudinal tangents can be parallel only in the case of a constant horizontal curvature. Since the spiral is used to connect track segments with different curvatures, the horizontal curvature cannot be assumed constant, and as a consequence, the right and left rail longitudinal tangents cannot be considered parallel in the spiral region. Numerical examples that demonstrate the effect of the errors that result from the assumption that the right and left rails in the spiral sections have the same geometry are presented. The numerical results obtained show that these errors can have a significant effect on the quality of the predicted creep contact forces.

Copyright © 2010 by American Society of Mechanical Engineers
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Figures

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Figure 4

Single truck model

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Figure 5

Left rail yaw angle (Method 1 —, Method 2 – – –)

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Figure 6

Difference in the left rail yaw angle

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Figure 7

Lateral displacement (Method 1 —, Method 2 – – –)

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Figure 8

Yaw angle (Method 1 —, Method 2 – – –)

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Figure 9

Lateral creepage at first point of contact (Method 1 —, Method 2 – – –)

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Figure 10

Lateral creepage at second point of contact (Method 1 —, Method 2 – – –)

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Figure 11

Lateral creep force at first contact point (Method 1)

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Figure 12

Lateral creep force at first contact point (Method 2)

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Figure 13

Lateral creep force at second contact point (Method 1)

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Figure 14

Lateral creep force at second contact point (Method 2)

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Figure 15

Net lateral force (Method 1)

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Figure 16

Net lateral force (Method 2)

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Figure 2

Effect of superelevation on grade

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