Fatigue strength and fracture mechanics – A general perspective

•Methodology for fracture mechanics application to fatigue strength.•Fatigue strength relevant initial crack size based on a two-criteria approach.•Method for multiple crack propagation.•Stochastic endurance limit and finite life fatigue strength predictions. Common fracture mechanics based fatigue...

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Bibliographic Details
Published in:Engineering fracture mechanics 2018-07, Vol.198, p.2-23
Main Authors: Zerbst, U., Madia, M., Vormwald, M., Beier, H.Th
Format: Article
Language:English
Subjects:
Crack closure
Crack propagation
Endurance limit
Fatigue cracks
Fatigue failure
Fatigue life
Fatigue limit
Fatigue strength
Fracture mechanics
Materials fatigue
Multiple cracking
S N diagrams
Short crack propagation
Short cracks
Weldments
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Summary:•Methodology for fracture mechanics application to fatigue strength.•Fatigue strength relevant initial crack size based on a two-criteria approach.•Method for multiple crack propagation.•Stochastic endurance limit and finite life fatigue strength predictions. Common fracture mechanics based fatigue considerations are usually limited to the residual lifetime determination of so-called long cracks. The extension of this concept to the total lifetime, as in the S-N curve approach, requires an adequate description of short crack propagation which cannot be based on the ΔK concept, and it must consider the crack closure phenomenon as well as its gradual build-up at the short crack stage. Further, it has to provide a meaningful definition of initial crack dimensions and a solution for the multiple crack problem at stress levels higher than the fatigue limit as it is specific for some configurations such as weldments. This paper aims at a discussion of all these points and offers possible solutions which are illustrated by examples taken from the German IBESS project on fracture mechanics based determination of the fatigue strength of weldments, the results of which will be discussed in more detail in this Special issue.
ISSN:0013-7944
1873-7315
DOI:10.1016/j.engfracmech.2017.04.030