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Review of modelling small-crack behavior and fatigue-life predictions for aluminum alloysThe small-crack effect, where small fatigue cracks grow faster and at lower stress-intensity factors than large cracks, has been found to be significant for many materials and loading conditions. In this paper, plasticity effects and crack-closure modelling of small fatigue cracks are reviewed. A crack-closure model with a cyclic-plastic-zone-corrected effective stress-intensity factor range (related to the cyclic J-integral) and microstructural data on crack-initiation sites were used to calculate small-crack growth rates and fatigue lives for unnotched and notched specimens made of two aluminum alloys. The crack-closure transient from the plastic wake was shown to be the dominant cause of the small-crack effect and plasticity effects on the cyclic-plastic-zone-corrected stress-intensity factor range were negligible except at extremely high stress levels. Small-crack growth rates and fatigue lives under both constant-amplitude and spectrum loading from tests and analyses agreed well.
Document ID
19950040084
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Newman, J. C., Jr.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 16, 2013
Publication Date
April 1, 1994
Publication Information
Publication: Fatigue and Fracture of Engineering Materials & Structures
Volume: 17
Issue: 4
ISSN: 8756-758X
Subject Category
Structural Mechanics
Accession Number
95A71683
Distribution Limits
Public
Copyright
Other

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