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An assessment of buffer strips for improving damage toleranceGraphite/epoxy panels with buffer strips were tested in tension to measure their residual strength with crack-like damage. Panels were made with 45/0/-45/90(2S) and 45/0/450(2S) layups. The buffer strips were parallel to the loading directions. They were made by replacing narrow strips of the 0 deg graphite plies with strips of either 0 deg S-Glass/epoxy or Kevlar-49/epoxy on either a one for one or a two for one basis. In a third case, O deg graphite/epoxy was used as the buffer material and thin, perforated Mylar strips were placed between the 0 deg piles and the cross-plies to weaken the interfaces and thus to isolate the 0 deg plies. Some panels were made with buffer strips of different widths and spacings. The buffer strips arrested the cracks and increased the residual strengths significantly over those plain laminates without buffer strips. A shear-lag type stress analysis correctly predicted the effects of layups, buffer material, buffer strip width and spacing, and the number of plies of buffer material.
Document ID
Document Type
Conference Paper
Poe, C. C., Jr.
(NASA Langley Research Center Hampton, VA, United States)
Kennedy, J. M.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 11, 2013
Publication Date
March 1, 1981
Publication Information
Publication: Supersonic Cruise Res., 1979, Pt. 2
Subject Category
Aircraft Design, Testing And Performance
Accession Number
Distribution Limits
Work of the US Gov. Public Use Permitted.

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