Mixed-mode I-II-III delamination toughness determination via a shear-torsion-bending test

Barry D. Davidson, Felipe O. Sediles

Research output: Contribution to journalArticlepeer-review

64 Scopus citations


A new "shear-torsion-bending" (STB) test is introduced that allows for delamination toughness testing under any ratio of mode I, II and III loading. STB test specimens are similar to those that are used for existing mode I, II and mixed-mode I-II test methods. Three-dimensional finite element analyses are used to show that the distributions of energy release rates across the delamination front are relatively uniform, with the variations being reasonably similar to those that occur in other widely accepted test methods. Closed-form data reduction methods are introduced and are verified for a wide range of material and geometric properties. Thus, the STB appears to be a promising test for evaluating mixed-mode toughnesses of laminated composites under conditions where mode III is present. Use of the STB is illustrated by mode III delamination toughness testing on two different carbon/epoxy materials.

Original languageEnglish (US)
Pages (from-to)589-603
Number of pages15
JournalComposites Part A: Applied Science and Manufacturing
Issue number6
StatePublished - Jun 2011


  • A. Polymer-matrix composites (PMCs)
  • B. Delamination
  • C. Finite element analysis (FEA)
  • D. Mechanical testing

ASJC Scopus subject areas

  • Ceramics and Composites
  • Mechanics of Materials


Dive into the research topics of 'Mixed-mode I-II-III delamination toughness determination via a shear-torsion-bending test'. Together they form a unique fingerprint.

Cite this