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Modeling the Interactions Between Multiple Crack Closure Mechanisms at ThresholdA fatigue crack closure model is developed that includes interactions between the three closure mechanisms most likely to occur at threshold; plasticity, roughness, and oxide. This model, herein referred to as the CROP model (for Closure, Roughness, Oxide, and Plasticity), also includes the effects of out-of plane cracking and multi-axial loading. These features make the CROP closure model uniquely suited for, but not limited to, threshold applications. Rough cracks are idealized here as two-dimensional sawtooths, whose geometry induces mixed-mode crack- tip stresses. Continuum mechanics and crack-tip dislocation concepts are combined to relate crack face displacements to crack-tip loads. Geometric criteria are used to determine closure loads from crack-face displacements. Finite element results, used to verify model predictions, provide critical information about the locations where crack closure occurs.
Document ID
20030053073
Acquisition Source
Langley Research Center
Document Type
Technical Memorandum (TM)
Authors
Newman, John A.
(Army Research Lab. Hampton, VA, United States)
Riddell, William T.
(Federal Aviation Administration Cambridge, MA, United States)
Piascik, Robert S.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
September 7, 2013
Publication Date
May 1, 2003
Subject Category
Structural Mechanics
Report/Patent Number
ARL-TR-2959
NAS 1.15:212402
NASA/TM-2003-212402
L-18279
Funding Number(s)
OTHER: 706-62-31-51
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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