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An assessment of the small-crack effect for 2024-T3 aluminum alloyData on small-crack behavior were obtained for a single-edge-notched tensile specimen made of 2024-T3 Al alloy and used to evaluate the capability of a semiempirical crack-growth and closure model to predict the fatigue life of notched specimens. Fatigue tests were conducted under either constant-amplitude loading (with stress ratios of 0.5, 0, -1, and -2) or spectrum loading, using a replication technique to record growth. It was found that small cracks exhibited the 'small-crack' effect in that they grew faster than large cracks when subjected to the same stress intensity factor range. Experimental small-crack growth rates agreed well with the model predictions. For making predictions of fatigue life, an initial surface defect void size of 3 x 12 x 0.4 microns was used in all calculations; predicted fatigue lives agreed well with experimentally determined values obtained in all tests. The crack-closure model indicated that the 'small-crack' effect on fatigue life was greatest in tests involving significant compressive loads.
Document ID
19870047394
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Newman, J. C., Jr.
(NASA Langley Research Center Hampton, VA, United States)
Swain, M. H.
(NASA Langley Research Center Hampton, VA, United States)
Phillips, E. P.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 13, 2013
Publication Date
January 1, 1986
Subject Category
Metallic Materials
Accession Number
87A34668
Distribution Limits
Public
Copyright
Other

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