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Fatigue crack initiation and small crack growth in several airframe alloysThe growth of naturally-initiated small cracks under a variety of constant amplitude and variable amplitude load sequences is examined for several airframe materials: the conventional aluminum alloys, 2024-T3 and 7075-T6, the aluminum-lithium alloy, 2090-T8E41, and 4340 steel. Loading conditions investigated include constant amplitude loading at R = 0.5, 0, -1 and -2 and the variable amplitude sequences FALSTAFF, Mini-TWIST and FELIX/28. Crack growth was measured at the root of semicircular edge notches using acetate replicas. Crack growth rates are compared on a stress intensity factor basis, to those for large cracks to evaluate the extent of the small crack effect in each alloy. In addition, the various alloys are compared on a crack initiation and crack growth morphology basis.
Document ID
19900009430
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Swain, M. H.
(Lockheed Engineering and Sciences Co. Hampton, VA., United States)
Newman, J. C., Jr.
(NASA Lewis Research Center Cleveland, OH., United States)
Phillips, E. P.
(NASA Lewis Research Center Cleveland, OH., United States)
Everett, R. A., Jr.
(Army Aerostructures Directorate Hampton, VA., United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1990
Subject Category
Structural Mechanics
Report/Patent Number
AVSCOM-TM-90-B-001
NAS 1.15:102598
NASA-TM-102598
Accession Number
90N18746
Funding Number(s)
PROJECT: RTOP 505-63-01-05
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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