A fiber-resin micromechanics analysis of the delamination front in a DCB specimen

Crews, J. H.; Shivakumar, K. N.; Raju, I. S.

A 3-D finite element model was developed to analyze the fiber-resin behavior near the delamination front in a graphite-epoxy double cantilever beam (DCB) specimen. The specimen interior was analyzed using a typical one-fiber slice, represented by a local 3-D fiber-resin model. The resin stresses were computed for the resin-rich layer at the ply interface as well as for the regions between the fibers close to the delamination front. However, the computed strain energy release rate G sub I along the delamination front varied by less than two percent, and was within about four percent of the plane-strain value. The von Mises yield criterion was used to estimate the extent of yielding near the delamination front. The yielding extended ahead of the delamination and also developed between the fibers. Although the fibers had only a negligible effect on G sub I, they caused yielding within the ply and therefore could influence delamination fracture toughness. The normal and shear stresses at the fiber-resin interface were computed near the delamination front. These results suggest that multi-axial stress criteria may be required to analyze fiber-resin interfaces.

Document ID

19880008353

Acquisition Source

Legacy CDMS

Document Type

Technical Memorandum (TM)

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Date Acquired

September 5, 2013

Publication Date

January 1, 1988

Subject Category

Report/Patent Number

Accession Number

88N17737

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Public

Work of the US Gov. Public Use Permitted.

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