PSI - Issue 28

C. Mallor et al. / Procedia Structural Integrity 28 (2020) 619–626

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C. Mallor et. al. / Structural Integrity Procedia 00 (2020) 000–000

4. Conclusions In summary, this work presents a propagation of uncertainty methodology for efficiently estimating the probability distribution of the fatigue crack growth lifetime. It implements the Pearson distribution family and uses the statistical moments of the lifetime predicted via the full second-order approach applied to the NASGRO model. The most important advantage of this method when compared to an equivalent Monte Carlo analysis is its performance, that is, its balance of accuracy and efficiency. The probability distribution constructed from the first four prescribed moments is helpful to describe the fatigue crack growth phenomenon under stochastic conditions such as under a random bending moment loading. Further investigations are required considering more input variables as random variables. For instance, the scatter of the fatigue crack growth curve can be studied within this methodology throughout the material parameters and in the NASGRO equation, modelled as a bivariate normal-lognormal distribution, and therefore accounting the inherent correlation between them. Moreover, extensive probabilistic analyses are still needed when dealing with random variables in fatigue design and damage tolerance assessment of railway axles. Acknowledgements The authors acknowledge the Spanish Ministry of Economy, Industry and Competitive through the National Programme for Research Aimed at the Challenges of Society that financially supported the project RTC-2016-4813-4. References [1] Zerbst U, Beretta S, Köhler G, Lawton A, Vormwald M, Beier HTh, et al. Safe life and damage tolerance aspects of railway axles – A review. Eng Fract Mech 2013;98:214–71. https://doi.org/10.1016/j.engfracmech.2012.09.029. [2] Zerbst U, Klinger C, Klingbeil D. 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