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THE NUCLEATION AND GROWTH OF SHORT FATIGUE CRACKS BOTH AT PLAIN SURFACES AND NOTCHES
Author(s) -
Guiu F.,
Stevens R. N.
Publication year - 1990
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1111/j.1460-2695.1990.tb00632.x
Subject(s) - nucleation , materials science , crack closure , structural engineering , stress concentration , fatigue testing , paris' law , deformation (meteorology) , stress (linguistics) , fatigue limit , point (geometry) , mechanics , fracture mechanics , composite material , engineering , mathematics , geometry , physics , thermodynamics , linguistics , philosophy
— The problem of the nucleation and growth of short fatigue cracks is addressed from an energetic point of view. It is explained that vanishingly small cracks can only nucleate and grow at the expense of the release of some locally stored energy during the fatigue deformation. This is necessary because an external loading system alone cannot provide a positive driving force for the growth of a crack whose length is below a critical value. The concept of the local driving force is used to explain the nucleation and growth of short fatigue cracks both at plain surfaces and at notches. With this approach a meaningful definition can be given of a “short fatigue crack” and a sound physical interpretation of the Kitagawa‐Takahashi plots is provided. The conditions for the existence of non‐propagating cracks are clearly established and the relationship between the stress concentration factor at the root of notches and the fatigue limit is explained. The paper sets up a physical framework for the sound understanding and treatment of short fatigue cracks and the microstructural parameters which control their growth.