On the Prediction of the Fatigue Life of Rails

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American Railway Engineering Association
This paper introduces a methodology for the calculation of the fatigue life of rails in service. The need for this methodology has arisen out of the trend towards increased wheel loads and the resulting fatigue-related problems. It is felt that this technique for the prediction of rail fatigue life will be of great value in both the construction and maintenance of main-line track. In this methodology, a service environment is represented by means of an environmental load spectra, which is then converted to stresses at the rail. Although this paper is restricted to flexural rail stresses, the methodology can be readily extended to other states of stress. Once the stress spectra is known, the fatigue life of the rail is calculated by means of Miner's linear cumulative damage theory, using appropriate material properties. In this analysis, the rail fatigue life at several stress levels is calculated for various rail sections. Additionally, the effect of track stiffness on the flexural fatigue life of different rail sections is determined. These results are presented as a set of curves. From these curves, the paper notes the detrimental effect of increased wheel loads on fail fatigue life. Furthermore, it is seen that a proper matching of rail size to anticipated wheel loads is necessary to reduce the occurrence of rail defects. Finally, it is seen that the sensitivity of the rail's flexural fatigue life to track stiffness is not as great as its sensitivity to wheel load, rail strength, or rail section size. The paper concludes with recommendations for additional work required to further develop and expand this technique.
Fatigue life, Rail fatigue, Rail sections
Abbott, R. A., & Zarembski, A. M., “On the Prediction of the Fatigue Life of Rails”, Bulletin of the American Railway Engineering Association, Bulletin 666, Volume 79, January - February 1978, p.p. 191-203.