Assessment of split-beam-type tests for mode III delamination toughness determination

Allison L. Johnston, Barry D. Davidson, Kiran K. Simon

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

Four split-beam-type tests are proposed for determining the mode III delamination toughness of laminated composite materials. Each test is first assessed via three dimensional finite element analysis. Experimental evaluations are then conducted, for which two different unidirectional carbon/epoxy materials are considered. For either material, it is shown that the same mode III toughness is obtained by the four different tests, provided that specimens with the same delamination length are tested. However, when a single test configuration is utilized to investigate the effect of delamination length, the apparent mode III toughness is observed to decrease with increasing delamination length. In order to understand the mechanisms behind this, transverse section cuts were taken at the delamination front of tested specimens. Photomicroscopic examinations of these cross sections revealed matrix cracks at the delamination front that were oriented at an inclination of 45â to the plane of the delamination. Based on previous observations of mode III crack initiation in homogeneous materials, it is hypothesized that these matrix cracks initiate prior to or concurrent with delamination advance, and therefore are responsible for the observed geometry-dependence of the mode III delamination toughness in laminated polymeric composites.

Original languageEnglish (US)
Pages (from-to)31-48
Number of pages18
JournalInternational Journal of Fracture
Volume185
Issue number1-2
DOIs
StatePublished - Jan 1 2014

Keywords

  • Delamination
  • Interlaminar
  • Matrix cracks
  • Mode III
  • Split-beam
  • Toughness

ASJC Scopus subject areas

  • Computational Mechanics
  • Modeling and Simulation
  • Mechanics of Materials

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