Effekte bei der Übertragbarkeit von probenbasierten Rissfortschrittsmodellen zur bruchmechanischen Bewertung von Radsatzwellen

Translated title of the contribution: Effects on transferability of specimen-based crack propagation models for fracture mechanical assessment of wheelset axles

David Simunek

Research output: ThesisDoctoral Thesis


The application of fracture-mechanical calculation methods for the assessment of fatigue crack growth and determination of inspection intervals for wheelset axles has gained importance in recent years. The currently primarily applied methods perform an assessment based on measured load spectra under consideration of long-crack growth models, such as the NASGRO model. By more recent approaches, the influence of load-time sequences in addition to the short crack behaviour can be taken into account leading to a more accurate prediction. To optimise and validate these methods, comprehensive experimental and computational investigations are generally necessary. For this reason, a rotating bending test technique was developed within the scope of this thesis to investigate the fatigue crack growth in wheelset axle test specimens on a scale of 1:3. With the help of this rotating bending test rig and a specially developed optical crack measurement, numerous crack propagation tests with the materials EA1N and EA4T were conducted. The test results show a significant scatter among each other, whereat the achieved lifetimes of the EA1N single-stage tests deviate up to a factor of 1.8. X-ray diffraction residual stress measurements show that due to the manufacturing of the 1:3 round specimens, tensile residual stresses up to 30 MPa were present, which led to accelerated crack growth. Due to the application of an enhanced assessment model, an improved estimation of the fatigue crack growth was achieved by considering the local residual stress state, whereby the deviation of the calculated service lifetime for the single-stage tests was reduced from previously more than 50 % to about 5 %. The validation of the load-time sequence model based on 1:3 experiments showed sound accordance, which highlights the importance of the considered retardation effect caused by overloads. The application of the extended crack propagation model for variable amplitudes emphasises, besides the influence of residual stresses, the potential of the load-time sequence model, whereby an optimised prediction of the fatigue crack propagation and thus of the to be defined inspection interval for wheelset axles can be achieved.
Translated title of the contributionEffects on transferability of specimen-based crack propagation models for fracture mechanical assessment of wheelset axles
Original languageGerman
Awarding Institution
  • Montanuniversität
  • Pippan, Reinhard, Assessor B (internal)
  • Grün, Florian, Assessor A (internal)
  • Leitner, Martin, Co-Supervisor (internal)
Publication statusPublished - 2020

Bibliographical note

embargoed until null


  • Fracture mechanics
  • Fatigue crack propagation
  • Wheelset axle
  • Retardation effects
  • Residual stresses

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