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A Test for Characterizing Delamination Migration in Carbon/Epoxy Tape LaminatesA new test method is presented for the purpose of investigating migration of a delamination between neighboring ply interfaces in fiber-reinforced, polymer matrix tape laminates. The test is a single cantilever beam configuration consisting of a cross-ply laminate with a polytetrafluoroethylene insert implanted at the mid-plane and spanning part way along the length of the specimen. The insert is located between a 0- degree ply (specimen length direction) and a stack of four 90-degree plies (specimen width direction). The specimen is clamped at both ends onto a rigid baseplate and is loaded on its upper surface via a piano hinge. Tests were conducted with the load-application point located on the intact portion of the specimen in order to initiate delamination growth onset followed by migration of the delamination to a neighboring 90/0 ply interface by kinking through the 90-degree ply stack. Varying this position was found to affect the distance relative to the load-application point at which migration initiated. In each specimen, migration initiated by a gradual transition of the delamination at the 0/90 interface into the 90-degree ply stack. In contrast, transition of the kinked crack into the 90/0 interface was sudden. Fractography of the specimens indicated that delamination prior to migration was generally mixed mode-I/II. Inspection of the kink surface revealed mode-I fracture. In general, use of this test allows for the observation of the growth of a delamination followed by migration of the delamination to another ply interface, and should thus provide a means for validating analyses aimed at simulating migration.
Document ID
20140000686
Acquisition Source
Langley Research Center
Document Type
Technical Memorandum (TM)
Authors
Ratcliffe, James G.
(National Inst. of Aerospace Hampton, VA, United States)
Czabaj, Michael W.
(NASA Langley Research Center Hampton, VA, United States)
O'Brien, Thomas K.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
February 12, 2014
Publication Date
August 1, 2013
Subject Category
Composite Materials
Report/Patent Number
NASA/TM-2013-218028
L-20305
NF1676L-17006
Funding Number(s)
WBS: WBS 794072.02.07.03.03
Distribution Limits
Public
Copyright
Public Use Permitted.
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