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Compression failure mechanisms of composite structuresAn experimental and analytical study was conducted to delineate the compression failure mechanisms of composite structures. The present report summarizes further results on kink band formation in unidirectional composites. In order to assess the compressive strengths and failure modes of fibers them selves, a fiber bundle was embedded in epoxy casting and tested in compression. A total of six different fibers were used together with two resins of different stiffnesses. The failure of highly anisotropic fibers such as Kevlar 49 and P-75 graphite was due to kinking of fibrils. However, the remaining fibers--T300 and T700 graphite, E-glass, and alumina--failed by localized microbuckling. Compressive strengths of the latter group of fibers were not fully utilized in their respective composite. In addition, acoustic emission monitoring revealed that fiber-matrix debonding did not occur gradually but suddenly at final failure. The kink band formation in unidirectional composites under compression was studied analytically and through microscopy. The material combinations selected include seven graphite/epoxy composites, two graphite/thermoplastic resin composites, one Kevlar 49/epoxy composite and one S-glass/epoxy composite.
Document ID
19860015947
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Hahn, H. T. (Washington Univ. Saint Louis, MO, United States)
Sohi, M. (Washington Univ. Saint Louis, MO, United States)
Moon, S. (Washington Univ. Saint Louis, MO, United States)
Date Acquired
September 5, 2013
Publication Date
June 1, 1986
Publication Information
Publisher: NASA
Subject Category
Composite Materials
Report/Patent Number
WU/CCR-85/5
NAS 1.26:3988
NASA-CR-3988
Accession Number
86N25419
Funding Number(s)
PROJECT: RTOP 534-06-23-08
CONTRACT_GRANT: NAG1-295
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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