Determination of Stress-Strain Characteristics of Railhead Steel using Image Analysis

Authors: Bandula-Heva, T., Dhanasekar, M.

Abstract:

True stress-strain curve of railhead steel is required to investigate the behaviour of railhead under wheel loading through elasto-plastic Finite Element (FE) analysis. To reduce the rate of wear, the railhead material is hardened through annealing and quenching. The Australian standard rail sections are not fully hardened and hence suffer from non-uniform distribution of the material property; usage of average properties in the FE modelling can potentially induce error in the predicted plastic strains. Coupons obtained at varying depths of the railhead were, therefore, tested under axial tension and the strains were measured using strain gauges as well as an image analysis technique, known as the Particle Image Velocimetry (PIV). The head hardened steel exhibit existence of three distinct zones of yield strength; the yield strength as the ratio of the average yield strength provided in the standard (σyr=780MPa) and the corresponding depth as the ratio of the head hardened zone along the axis of symmetry are as follows: (1.17 σyr, 20%), (1.06 σyr, 20%-80%) and (0.71 σyr, > 80%). The stress-strain curves exhibit limited plastic zone with fracture occurring at strain less than 0.1.

Keywords: Stress-Strain Curve, Tensile Test, Particle Image Velocimetry, Railhead Metal Properties

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1083587

References:

[1] X. Zhan. and S. Wang, "Research on the improvement of Rail head hardening technology on Railway," Journal of the Eastern Asia Society for Transportation Studies, vol. 5, pp. 263-271, 2005.
[2] D.F. Cannon and H. Pradier, "Rail rolling contact fatigue research by the European Rail Research Institute," Wear, vol. 191, pp. 1-13, 1996.
[3] A.K. Hellier and A.A. Merati, "The mode I fatigue threshold for head hardened rail steel," International Journal of Fatigue, vol. 20, pp. 247- 249, 1998.
[4] AS 1085.1., Standards-Australia., " Railway track materials, Part 1: Steel rails," Australian Standard, 2002.
[5] S. Rajanna, H.K. Shivanand, and B.N. Akash Deep, "Improvement in mechanical behavior of expulsion with heat treated thermite welded rail steel," Proceedings of World Academy of Science, Engineering and Technology, vol. 60, pp. 558-562, 2009.
[6] T. Anapayan, M. Mahendran, and D. Mahaarachchi, "Lateral distortional buckling tests of a new hollow flange channel beam," Thin-Walled Structures, vol. 49, pp. 13-25, 2011.
[7] M. Qin, V. Ji, Y.N. Wu, C.R. Chen, and J.B. Li, "Determination of proof stress and strain-hardening exponent for thin film with biaxial residual stresses by in-situ XRD stress analysis combined with tensile test," Surface and Coatings Technology, vol. 192, pp. 139-144, 2005.
[8] E. Rivera, D.J. Thomson, and A.A. Mufti, "Comparison of recoated fiber Bragg grating sensors under tension on a steel coupon," in Nondestructive Evaluation and Health Monitoring of Aerospace Materials, Composites, and Civil Infrastructure IV, 2005, pp. 163-174.
[9] H. Hoffmann and C. Vogl, "Determination of True Stress-Strain-Curves and Normal Anisotropy in Tensile Tests with Optical Strain Measurement," CIRP Annals - Manufacturing Technology, vol. 52, pp. 217-220, 2003.
[10] K. Ichinose, K. Fukuda, K. Gomi, K. Taniuchi, and M. Sano, "Yield strength in relation to cyclic loading," Journal of Testing and Evaluation, vol. 29, pp. 529-34, 2001.
[11] Y. Lianxiang, S. Lorenzo, G. Abhishek, and C. Xu, "Measure Strain Distribution Using Digital Image Correlation (DIC) for Tensile Tests," The Advanced High Strength Steel Stamping Team of the Auto/Steel Partnership (A/SP) 2010.
[12] R.J. Adrian, "Particle-Imaging Techniques for Experimental Fluid Mechanics," Annual Review of Fluid Mechanics, vol. 23, pp. 261-304,1991.
[13] M. Raffel, C.E. Willert, S.T. Wereley, and J. Kompenhans, "Particle Image Velocimetry : A Practical Guide," Springer, 2007.
[14] D.J. White, W.A. Take, and M.D. Bolton, "Soil deformation measurement using particle image velocimetry (PIV) and photogrammetry," Geotechnique, vol. 53, pp. 619-631, 2003.
[15] D.J. White and W.A. Take, "GeoPIV: particle image velocimetry (PIV) software for use in geotechnical testing (Technical Report)," Cambridge University Department of Engineering 2002.
[16] D.J. White, W.A. Take, and M.D. Bolton, "Measuring soil deformation in geotechnical models using digital images and PIV analysis," in 10th International Conference on Computer Methods and Advances in Geomechanics. Tucson, Arizona., 2001, pp. 997-1002.
[17] N.I. Thusyanthan, W.A. Take, S.P. Madabhushi, and M.D. Bolton, "Crack initiation in clay observed in beam bending," Geotechnique, vol. 57, pp. 581-594, 2007.
[18] AS1391., Standard-Australia., "Metallic materials-Tensile testing at ambient temperature," Australian Standard, 2007.
[19] J.M. Gere. and B.J. Goodno., "Stress-Strain Diagrams," in Mechanics of materials 7th ed: Cengage Learning, 2009, p. 19.