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A Novel Method for Characterizing Fatigue Delamination Growth Under Mode I Using the Double Cantilever Beam SpecimenA novel method is proposed to obtain Mode I delamination growth rate from a Double Cantilever Beam (DCB) specimen. In the proposed method, Unidirectional (UD) DCB specimens are tested in fatigue at different initial maximum energy release rates levels. The growth rate data obtained in the first increments of crack growth at each maximum energy release rate level are used to generate a Paris Law equation, which characterizes delamination growth rate without fiber-bridging, and can also be used to determine a delamination onset curve. The remaining delamination growth rate data from each test are used to determine a modified Paris law, which characterizes the delamination growth rate in a DCB specimen, explicitly accounting for fiber-bridging. The proposed expression captures well the scatter in experimental data obtained using the DCB specimens, suggesting its adequacy. The Paris Law characterizing delamination growth rate without fiber-bridging predicts higher delamination growth rates for the same maximum energy release rate applied, leading to a conservative estimate for delamination growth. This is particularly relevant, since in generic ply interfaces, fiber-bridging is less predominant than in UD DCB specimens. Failing to account for fiber-bridging in UD DCB specimens may underestimate the delamination growth rate, yielding non-conservative predictions.
Document ID
20140016382
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Carvalho, Nelson
(National Inst. of Aerospace Hampton, VA, United States)
Murri, G.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
November 17, 2014
Publication Date
September 8, 2014
Subject Category
Composite Materials
Report/Patent Number
NF1676L-18061
Meeting Information
Meeting: US-Japan Conference on Composite Materials
Location: La Jolla, CA
Country: United States
Start Date: September 8, 2014
End Date: September 10, 2014
Sponsors: Japan Society for Composite Materials, American Society for Composites
Funding Number(s)
WBS: WBS 794072.02.07.03.03
Distribution Limits
Public
Copyright
Public Use Permitted.
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