Running on Straight Rails

Boffins in Austria have been studying railway tracks to better understand the residual stresses that result from straightening them during processing.

Roller straightening is the final step in production of the rails, after hot rolling is performed at around 1000&degree;C cooling (presumably with water spray) results in curvature of the rails. This varies depending on the rail geometry and cooling conditions.
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Results from finite element modelling, and measurement of stresses using the contour method and neutron diffraction were compared. The model matches the trends of the measurements in the vertical plane (possibly the mode important since it has the largest residual stresses). In the paper comparison of neutron results for triaxial stresses shows there are residual stresses in the plane perpendicular to the vertical through the rail tool, although these were not predicted by the FEM model.

Residual Stresses

Residual Stresses along vertical symmetry axis

References

  1. http://phys.org/news/2015-01-rails-straight.html#nRlv
  2. R. Kaiser, M. Stefenelli, T. Hatzenbichler, T. Antretter, J. Keckes and B. Buchmayr (2014) “Experimental characterization and modelling of triaxial residual stresses in straightened railway rails,” The Journal of Strain Analysis for Engineering Design, 1-9 DOI: 10.1177/0309324714560040

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