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Dislocation mechanism based model for stage II fatigue crack propagation rateRepeated plastic deformation, which of course depends on dislocation mechanism, at or near the crack tip leads to the fatigue crack propagation. By involving the theory of thermally activated flow and the cumulative plastic strain criterion, an effort is made here to model the stage II fatigue crack propagation rate in terms of the dislocation mechanism. The model, therefore, provides capability to ascertain: (1) the dislocation mechanism (and hence the near crack tip microstructures) assisting the crack growth, (2) the relative resistance of dislocation mechanisms to the crack growth, and (3) the fracture surface characteristics and its interpretation in terms of the dislocation mechanism. The local microstructure predicted for the room temperature crack growth in copper by this model is in good agreement with the experimental results taken from the literature. With regard to the relative stability of such dislocation mechanisms as the cross-slip and the dislocation intersection, the model suggests an enhancement of crack growth rate with an ease of cross-slip which in general promotes dislocation cell formation and is common in material which has high stacking fault energy (produces wavy slips). Cross-slip apparently enhances crack growth rate by promoting slip irreversibility and fracture surface brittleness to a greater degree.
Document ID
19870035714
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Mazumdar, P. K.
(Tuskegee University AL, United States)
Date Acquired
August 13, 2013
Publication Date
December 1, 1986
Publication Information
Publication: Acta Metallurgica
Volume: 34
ISSN: 0001-6160
Subject Category
Structural Mechanics
Accession Number
87A22988
Funding Number(s)
CONTRACT_GRANT: NAG8-20
Distribution Limits
Public
Copyright
Other

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