Auswirkungen verschiedener Lastinteraktionen auf das Lebensdauerverhalten eines Vergütungsstahls

Translated title of the contribution: Effects of Various Load Interactions on Fatigue Life of Quenched and Tempered Steel

Christian Garb

Research output: ThesisDiploma Thesis


The importance of considering complex load histories and overloads in fatigue life prediction models of components and structures increased since the last few decades. State of the art prediction models barely take into account various load interactions. The aim of the present work is to develop a methodology and to evaluate the most important measurement parameters in order to determine the influence of complex load interactions. Quenched and tempered steel has been used for the investigations in the present work. Quasi-static experiments have been carried out in order to examine the static deformation process under tensile and compressive load conditions. The stress-strain-response was described by an approximation function. The influence on the fatigue life of cyclic pre-load conditions at high mean stresses was investigated. Additionally the amount of pre-load cycles was varied. It has been found that only the first cycles of the pre-loadings have a significant influence on the number of cycles to failure. Furthermore the consequence of static pre-strains on the fatigue life was observed. The pre-strain level as well as the stress amplitudes of the following alternating cyclic loading was varied. The results were first analyzed using ASTM E 739, a standard practice for statistical analysis of fatigue data, for each stress amplitude level. Increasing pre-strain levels resulted in a decrease of the fatigue life of the material. The prevailing results can be approximated by an approach using three parameters, which adequately describes the influence of pre-strains on the number of cycles to failure. Additionally a life prediction model based on static material parameters which respects quasi static pre-strains is presented. Finally the effect of the chronology as well as the amount of overloads on the fatigue life was examined. Overloads at an early life stage showed a more pronounced effect on the fatigue life. In addition periodic overloads lead to a higher reduction in lifetime than block-overloads.
Translated title of the contributionEffects of Various Load Interactions on Fatigue Life of Quenched and Tempered Steel
Original languageGerman
  • Strohhäussl, Bernd, Co-Supervisor (internal)
  • Grün, Florian, Supervisor (internal)
Award date27 Jun 2014
Publication statusPublished - 2014

Bibliographical note

embargoed until null


  • life prediction model
  • pre-strain
  • overload
  • ratcheting
  • cold work hardening
  • load chronology
  • fatigue life

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