Retardationseffekte beim Ermüdungsrisswachstum in ausgewählten Stahlwerkstoffen

Translated title of the contribution: Retardation effects on fatigue crack growth of selected steel materials

Arthur Lintner

Research output: ThesisMaster's Thesis


The issue of fatigue fractures in technical practice began at the time of the invention of the railway. Until today, the fatigue design of the high-cyclically rotating bending loaded railway axle preoccupies science. Surface damages caused by stone impacts or corrosion favour the initiation of fatigue cracks, which may propagate to a critical dimension under the operational load and enforce a non-destructive testing in regular intervals. The definition of these maintenance intervals requires an accurate knowledge of the crack growth, which is significantly influenced by crack closing mechanisms in course of the variable in-service loading scenarios. This work provides a comprehensive literature research of the scientific fundamentals of linear-elastic fracture mechanics and knowledge of fatigue crack growth under operational loads. In the course of the experimental investigations two different specimen geometries were machined out of railway test axles made of the materials EA1N and EA4T. The influence of oxide-induced crack-closure mechanism was investigated utilizing SENB-specimens, which were tested under alternating four-point bending. The results demonstrate a delay of the load cycles of up to 180,000 cycles due to oxide-induced crack-closure. Applying the direct potential method to measure the crack propagation involves computation of the crack length using the JOHNSON formula, which was verified by a numerical analysis. Rotating bending tests utilizing a round specimen with a diameter of 55 mm were conducted to investigate the effects of overloads with different overload ratios as well as oxide-induced crack closure. The crack propagation on the surface of the specimen was recorded by an optical system. Increasing the overload ratio from 1.5 to 2.5 improved the life-time gain by a factor of more than three and caused a delay lifetime of up to 391,000 load cycles. Compared to the SENB experiments, the round specimen tests revealed only minor oxide-induced retardation effects; hence, this influence needs further investigation considering real load spectra in the future.
Translated title of the contributionRetardation effects on fatigue crack growth of selected steel materials
Original languageGerman
Awarding Institution
  • Montanuniversität
  • Simunek, David, Co-Supervisor (internal)
  • Leitner, Martin, Co-Supervisor (internal)
  • Grün, Florian, Supervisor (internal)
Award date29 Jun 2018
Publication statusPublished - 2018

Bibliographical note

embargoed until 25-06-2023


  • fatigue crack growth
  • crack closure
  • overloads
  • retardation effects

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