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Applications: Railroad Rail

 
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   - make cut
   - measure surface
   - calculate stress
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Residual Stress
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Full results in: download pdf preprint The Contour Method, Michael B. Prime and Adrian T. DeWald, 2013, chapter 5 in Practical Residual Stress Measurement Methods, Gary S. Schajer, Editor, pp. 109-138.

New rail only in download preprint J. Kelleher, M.B. Prime, D. Buttle, P.M. Mummery, P.J. Webster, J. Shackleton, P.J. Withers, "The Measurement of Residual Stress in Railway Rails by Diffraction and Other Methods," Journal of Neutron Research, 11(4), 187-193, 2003. (LA-UR-03-7128)

Results:

Longitudinal stress in railway rails

The contour method results are unprecedented in revealing detailed stress maps in the rails. The longitudinal stresses have changed over the years of service. Wear has produced a compressive stress region at the surface. Plasticity has shifted and increased the sub-surface tensile stress.

Rail material and EDM Cut:

  • Two British rails
    • a new roller straightened rail
    • a rail that had undergone 23 years of service
  • BS 11 normal grade pearlitic steel with the standard 113A profile
  • Wire EDM Cut
    • Mitsubishi FX-10 wire EDM machine
    • 0.25 mm diameter brass wire.
    • Epak 1312: skim cut 1 settings for 75 mm thick hardened steel.
EDM wire cut of rail

Measure contour:

  • Keyence LT-8105 confocal ranging probe
    • scanned in the horizontal direction at a sampling rate of 16 points/mm
    • rows were spaced vertically to give 4 rows per mm
Laser scan of rail contour

Surface contour:

  • Shown on worn rail
  • The peak-to-valley range of the contours was about 75 µm
Surface contour on rail

3D FEM:

3D FEM mesh of rail

3D FEM deformed shape:

  • Displacement boundary conditions have been applied to elastically deform the model into the opposite of the shape measured on the cut surface.
FEM rail model deformed into opposite of measured shape

 

 

 

 

 

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Operated by Los Alamos National Security, LLC for the U.S. Department of Energy's NNSA
contact: Mike Prime at prime@lanl.gov | Copyright & Disclaimer
U.S. patent 6,470,756 | Last Modified: October 9, 2015

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