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Investigation of the Leak Response of a Carbon-Fiber Laminate Loaded in Biaxial TensionDesigners of pressurized structures have been reluctant to use composite materials because of concerns over leakage. Biaxial stress states are expected to be the worst-case loading condition for allowing leakage to occur through microcracks. To investigate the leakage behavior under in-plane biaxial loading, a cruciform composite specimen was designed that would have a relatively large test section with a uniform 1:1 biaxial loading ratio. A 7.6-cm-square test section was desired for future investigations of the leakage response as a result of impact damage. Many iterations of the cruciform specimen were evaluated using finite element analysis to reduce stress concentrations and maximize the size of the uniform biaxial strain field. The final design allowed the specimen to go to relatively high biaxial strain levels without incurring damage away from the test section. The specimen was designed and manufactured using carbon/epoxy fabric with a four-ply-thick, quasi-isotropic, central test section. Initial validation and testing were performed on a specimen without impact damage. The specimen was tested to maximum biaxial strains of approximately 4500micro epsilon without apparent damage. A leak measurement system containing a pressurized cavity was clamped to the test section and used to measure the flow rate through the specimen. The leakage behavior of the specimen was investigated for pressure differences up to 172 kPa
Document ID
20140002899
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Jackson, Wade C.
(NASA Langley Research Center Hampton, VA, United States)
Ratcliffe, James G.
(National Inst. of Aerospace Hampton, VA, United States)
Date Acquired
April 14, 2014
Publication Date
September 9, 2013
Subject Category
Composite Materials
Report/Patent Number
NF1676L-16727
Meeting Information
Meeting: American Society for Composites Annual Technical Conference
Location: State College, PA
Country: United States
Start Date: September 9, 2013
End Date: September 11, 2013
Sponsors: American Society for Composites
Funding Number(s)
WBS: WBS 794072.02.07.03.03.03
Distribution Limits
Public
Copyright
Public Use Permitted.
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