Fatigue crack propagation in engineering materials has been the subject of considerable research, and extensive review articles have appeared over the past several years. Most of these investigations focused on the behaviour of ‘long’ fatigue cracks, even though the characteristics associated with the extension of small cracks in metals and alloys remain relatively unexplored, despite their unquestionable importance from an engineering standpoint. In this review, the mechanics and micromechanisms of the subcritical growth of short fatigue cracks are examined, and aspects of their propagation behaviour are contrasted with those of long cracks in terms of fracture mechanics, microstructure, and environment. Cracks are defined as being short (i) when their length is small compared to relevant microstructural dimensions (a continuum mechanics limitation), (ii) when their length is small compared to the scale of local plasticity (a linear elastic fracture mechanics limitation), or (iii) when they are s...

Propagation of short fatigue cracks

Mechanisms for fatigue crack closure under plane strain conditions have recently been identified at very low (near-threshold) stress intensities in terms of effects of excess corrosion deposits or fracture surface roughness in promoting premature closure of the crack. In the present paper, a geometric model is presented for crack closure induced by fracture surface roughness. This model specifically addresses the contribution from both Mode I and Mode II crack tip displacements in addition to considering the nature of the fracture surface morphology. The implications of this model are briefly discussed in light of the roles of grain size, yield strength, microstructure, and crack size in influencing near-threshold fatigue behavior in engineering alloys.

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A geometric model for fatigue crack closure induced by fracture surface roughness

https://www2.lbl.gov/ritchie/Library/PDF/1986_Ritchie_MatSciEng_SmallFatigueCracks.pdf

Small fatigue cracks: A statement of the problem and potential solutions

Near-threshold fatigue crack growth behavior in metals

https://courses.washington.edu/mengr541/ramulu/541/notes/shortcrackmodelreview.pdf

Short fatigue crack behaviour and analytical models: a review

https://escholarship.org/content/qt557550tg/qt557550tg.pdf?t=p0wsyq

J.F. McCarver

Papers

Fatigue crack propagation thresholds for long and short cracks in René 95 Nickel-base superalloy