Application of Damage Tolerant Design in Mechanical Engineering

Miraj Muhammad Jan

Research output: ThesisDoctoral Thesis

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Abstract

In this thesis, the three primary fatigue design approaches stress-life, strain-life, and DTD are used to analyse fatigue damage with special focus on investigating flaws typically encountered in structural parts. The fatigue limit of undamaged and damaged specimens is assessed experimentally as well as theoretically. An effort is made to combine the existing concepts and to re-interpret the results obtained by the DTD and strain-life approaches in the framework of the conventional stress-life method. For a material containing defects, the idea of net section yielding is exploited to transform the S/N curve of an undamaged material to a damaged one. Finally, a method is proposed for obtaining an estimate of the fatigue lifetime of a component with and without defects using the static tensile properties in combination with the fatigue crack growth properties of the material. A guideline for obtaining a first estimate of fatigue data useful for purposes of preliminary design is developed and verified experimentally for a wrought aluminium alloy typically used for cryogenic applications. As a practical design application, the fatigue response of thin-walled tubular specimens is considered. A special rig having the capability of testing various materials such as aluminium and steel alloys under arbitrary combinations of static and/or periodic internal pressure and axial loading has been designed. First promising results for aluminium tubes under static internal pressure and axial fatigue loading are presented.
Translated title of the contributionAnwendung schadenstoleranter Auslegungsmethoden im Maschinenbau
Original languageEnglish
QualificationDr.mont.
Supervisors/Advisors
  • Pettermann, Heinz E., Assessor B (external), External person
  • Eichlseder, Wilfried, Assessor A (internal)
Publication statusPublished - 2008

Bibliographical note

embargoed until null

Keywords

  • fatigue life prediction
  • fatigue crack growth
  • S/N curve
  • HCF
  • LCF
  • damage tolerant design
  • aluminium alloy

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