Crack propagation life of detail fractures in rails

In this paper, fatigue crack growth rate data generated for head-hardened rail are used to examine the fatigue crack growth life of detail fractures under nominal revenue service conditions.

Moreover, this paper applies a probabilistic approach to estimate rail life to account for the inherent variability or scatter typically observed in fatigue crack growth rate data. Regression methods are employed to derive the parameters for the Walker crack growth rate equation, which are subsequently treated as correlated, multivariate, and normally distributed random variables.

Monte Carlo simulations of fatigue growth of detail fractures are carried out to estimate fatigue life distributions for each of the different rails. The results from these four rail steels are compared to those based on the previous research for non-head-hardened rails. Implications of these comparisons on determining rail testing intervals are discussed.

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Conference Sponsors: Rail Transportation Division. Previous Paper Next Paper. Article Navigation. Jeong , David Y. Independent Author. This Site. Google Scholar. Pawel Woelke Pawel Woelke.

Author Information. David Y. Pawel Woelke. Published Online: July 23, Abstract The most common rail defect encountered in continuously welded rail is known as the detail fracture. Volume Subject Area:. We cannot guarantee that every book is in the library! Compatible with any devices. The title of that conference was "Residual Stresses in Rails - Effects on Rail Integrity and Railroad Economics" and its themes were the measurement and prediction of residual stresses in rails, but, as the sub-title suggests, the intention was also to provide a link between research and its application to the practical railway world.

At the Cracow conference there were 40 participants with 5 railways and 5 rail makers being represented and 25 papers were given.

It turned out to be some baby, with delegates from 24 countries taking part! As with its predecessor, the conference was to provide a forum for the exchange of ideas between research investigators, rail makers and railway engineers. Bearing in mind that some of the railway industry participants were from their respective research and development organisations the balance of interests was about right. This report develops a fracture mechanics model for railhead transverse defects, specifically detail fractures from rail shell.

The model is applied to calculate the failure strength of 71 rail segments which were rejected by inspection, removed, and tested by the Association of American Railroads in three-point bending. Utilizing the defect measurements for each rail, reasonable agreement is obtained between observed failure loads and failure loads calculated from the stress and fracture mechanics analyses. The fracture mechanics analysis is then extended to obtain preliminary estimates of the fatigue performance of defective rails in service.

Specifically, the crack tip stress intensity factor is calculated for transverse defects under various types of in-service loading.

The fracture mechanics solutions are utilized to calculate conservatively the remaining lifetime of the rail as a function of defect size and magnitude of wheel load. Using a simplified two-dimensional stress analysis and a three-dimensional fracture mechanics analysis, it is calculated that the shear stress reversal experienced as the wheel passes from one side to the other side of a transverse crack is the dominant stress component causing fatigue crack propagation.

Recommendations are made for additional analytical developments and experimental programs required to refine the fatigue life predictions and incorporate them into rail risk assessment and reliability optimization programs. These volumes contain contributions from a conference on the themes of measurement and prediction of residual stress in railroad rails. The first volume features practical railway experience and laboratory tests, while the second one presents theoretical and numerical analyses.

The 13 cases involve new designs, rework designs, failure analysis, prototype decisions, environmental aspects, metals, non-metals, components, structures, and fasteners. The cases bring out the need for students to integrate elements of engineering that commonly enter into a fatigue design or failure analysis.

No index. Annotation copyright by Book News, Inc. Rail integrity is a current application of engineering fracture mechanics at a practical level. Although railroad rails have been manufactured and used for more than a century, it is only in the last ten years that the effects of their crack propagation and fracture characteristics have been considered from a rational viewpoint. Rail fatigue crack propagation rates and fracture resistance are strongly influenced by residual stresses, which are introduced into the rail both during proouction and in service.