Prediction of contact-fatigue damage to rails using computational-experimental methods

Analysis of the operational data related to rails failure showed that contact-fatigue defects consistently hold a prominent place. The goal of the study is to show the possibilities of using modern numerical methods in calculation assessment of the service life of rails before the onset of contact fatigue crack formation on a running surface depending on the values of axial load. To calculate a stress-strain state in the area of contact interaction between the wheel and rail a detailed finite-element model implemented in the MSC. Marc software package is used. The analysis revealed complex multiaxial and non-proportional nature of the stress-strain state. The Brown – Miller multiaxial fatigue model implemented in the MSC. Fatigue software package was taken to determine accumulation of the contact fatigue damages on a rail running surface. The model is based on the assumption that maximum fatigue damages in the metal occur in the area with the maximum shear stress. The impact of normal stresses in this area is also taken into account. The results of a comparative computational analysis of the rail life time confirm that the service life decreases with increasing axial loads, all other conditions being the same. With a share of 20% of freight trains with axle loads of 25 tonf in a daily pattern one should expect a decrease in the contact fatigue life of rails by 3 – 4 %. It is possible to improve the method for prediction of the contact fatigue life of rails in terms of experimental definition of the fatigue and strength characteristics of the rail steel depending on the degree of hardening of the running surface, their probabilistic properties and the use of a cumulative distribution of vertical forces taking into account the structure of the freight traffic passing through the section.

1. Shur E. A., Borts A. I., Sukhov A. V., et al. The formation of contact-fatigue defects in the rail head / Zheleznodor. Transport. 2015. N 12. P. 34 – 38 [in Russian].

2. Lisitsyn A. I. Problems of increasing the overhaul period of rails from 700 to 1,500 million tons gross / Put’ Putevoe Khoz. 2015. N 5. P. 13 – 15 [in Russian].

3. Lysyuk V. S. Comparative tests of durability of rails / Put’ Putevoe Khoz. 2005. N 2. P. 23 – 25 [in Russian].

4. Bogdanov O. K., Nozdrachev G. S. The statistical analysis of defective rails with defect 21 / Put’ Putevoe Khoz. 2017. N 2. P. 26 – 33 [in Russian].

5. Poroshin V. L. The assessment of the rail damageability due to defects in case of increasing speeds / Trudy VNIIZhT. 1979. Issue 614. P. 54 – 65 [in Russian].

6. Johnson K. Contact mechanics. — Moscow: Mir, 1989. — 510 p. [Russian translation].

7. Akhmetzyanov M. Kh. About the mechanism of developing contact fatigue damages in rails / Vestn. VNIIZhT. 2003. N 2. P. 41 – 45 [in Russian].

8. Goryacheva I. G., Zakharov S. M., Torskaya E. V. Rolling contact fatigue and wear of wheel/rail simulation / Proceedings of the second International conference on rail technology research development and maintenance. Paper 0123456789. — Stirlingshire: Civil-Comp Press, 2014. — 15 p.

9. Trummer G., Six K., Woelfle A., et al. Comparison of rolling contact fatigue crack initiation models under heavy haul conditions / Proceedings of the International heavy haul conference IHHA-2017 (Cape Town, SA, 2017). Cape Town. 2017. P. 79 – 84.

10. Zakharov S. M., Torskaya E. V. Approaches to simulate the occurrence of surface contact fatigue damages in rails / Vestn. VNIIZhT. 2018. Vol. 77. N 5. P. 259 – 268 [in Russian].

11. Makhutov N. A., Reznikov D. O., Kossov V. S., Oganyan E. S., Volokhov G. M., Ovechnikov M. N., Protopopov A. L. Methods to determine the life time of non-redundant load-bearing elements of rolling stock and track / Byull. Ob’’ed. Uch. Soveta OAO «RZhD». 2017. N 3. P. 19 – 39 [in Russian].

12. Sakalo V. I., Sakalo A. V. The choice of a criterion to simulate the accumulation of contact fatigue damages in wheels of railway rolling stock / IV scientific and technical workshop «Computer-aided simulation in railway transport: dynamics, strength, wear» (Bryansk, April 3 – 4, 2018). Bryansk, 2018. P. 63 – 70 [in Russian].

13. Makhutov N. A., Sosnovsky L. A., Kebikov A. A. The method to assess the mechanical state of the rail material after the continuous operation / Zavod. Lab. Diagn. Mater. 2007. Vol. 73. N 8. P. 49 – 54 [in Russian].

14. Brown M. W., Miller K. J. A theory for fatigue failure under multiaxial stress-strain conditions / Proceedings of the institute of mechanical engineers. 1973. Vol. 187. P. 745 – 755.

15. Chung Lun Pun, Welsby D., Mutton P., Yan W. Rolling contact fatigue life predictions for rails and welds in heavy haul / Proceedings of the International heavy haul conference IHHA-2017 (Cape Town, SA. 2017). Cape Town. 2017. P. 56 – 62.

16. Troshchenko V. T., Khamaza L. A. Deformation curves for fatigue steels and methods for determining its parameters. Message 1. Traditional methods / Strength issues. 2010. N 6. P. 26 – 44.

17. Kossov V. S., Volokhov G. M., Krasnov O. G., Ovechnikov M. N., Protopopov A. L., Oguenko V. V. The influence of rolling stock axial loads on the contact fatigue life time of rails / Vestn. VNIIZhT. 2018. Vol. 77. N 3. P. 149 – 156 [in Russian].