Intrinsic coupling of near-tip matrix crack formation to mode III delamination advance in laminated polymeric matrix composites

A. L. Johnston, B. D. Davidson

Research output: Contribution to journalArticle

21 Scopus citations

Abstract

Laminated carbon/epoxy specimens are loaded in anti-plane shear to investigate the relationship between near-tip matrix crack formation and the apparent mode III delamination toughness. Specimens are tested with different insert lengths to various load levels and examined fractographically. Near-tip matrix cracks are found to initiate and propagate intralaminarly before the onset of planar growth. These cracks are inclined at approximately 45° to the delamination plane and are perpendicular to the direction of maximum near-tip tensile stress. It is found that this represents an intrinsically coupled sequence of events for anti-plane shear loading of continuous fiber laminated polymeric composites when a preexisting delamination is bounded by plies that have their fiber direction aligned with the direction of macroscopic advance. This sequence of events violates the assumptions used in the reduction of data from common mode III tests. It therefore invalidates the associated toughness measurements, and may account for or strongly contribute to the common observation that laminated polymeric composites exhibit an apparent mode III delamination toughness that is dependent on test geometry.

Original languageEnglish (US)
Pages (from-to)2360-2369
Number of pages10
JournalInternational Journal of Solids and Structures
Volume51
Issue number13
DOIs
StatePublished - Jun 15 2014

Keywords

  • Delamination
  • Energy release rate
  • Fiber reinforced composite materials
  • Fracture toughness

ASJC Scopus subject areas

  • Modeling and Simulation
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Applied Mathematics

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