Three dimensional analysis and resulting design recommendations for unidirectional and multidirectional end-notched flexure tests

B. D. Davidson, R. Kruger, M. König

Research output: Contribution to journalArticle

63 Scopus citations

Abstract

Results are presented from a theoretical investigation of the effects of stacking sequence on the energy release rate in laminated composite end-notched flexure test specimens. Deflections and energy release rates of unidirectional and multidirectional ENF specimens are obtained by classical laminated plate theory, shear deformable plate theory, and three dimensional finite element analyses. It is shown that the distribution of energy release rate varies across the front of an initially straight delamination. The percentage of mode II and mode III energy release rates for the specimen, as well as the local peak values of the mode II, mode III and total energy release rates that occur at the specimen's free edges are shown to correlate with a nondimensional ratio comprised of the specimen's flexural rigidities. The results of the study are used as a basis for a proposed “ENF test design procedure” that may be used for the determination of appropriate specimen stacking sequences and test geometries for studying delamination growth at interfaces between plies at various orientations. The test design procedure minimizes the contributions to the energy release rate from residual thermal stresses, geometric nonlinearities, local mode II concentrations at the specimen's free edges and local mode III effects.

Original languageEnglish (US)
Pages (from-to)2108-2133
Number of pages26
JournalJournal of Composite Materials
Volume29
Issue number16
DOIs
StatePublished - Nov 1995

Keywords

  • composite materials
  • delamination
  • end-notched flexure
  • energy release rate
  • fracture
  • fracture toughness
  • graphite/epoxy
  • mode II

ASJC Scopus subject areas

  • Ceramics and Composites
  • Mechanics of Materials
  • Mechanical Engineering
  • Materials Chemistry

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