Elsevier

Engineering Fracture Mechanics

Volume 149, November 2015, Pages 326-337
Engineering Fracture Mechanics

Novel experimental procedure and determination of full displacement fields of delaminating composite layer interfaces for evaluation of the mode II cohesive law

https://doi.org/10.1016/j.engfracmech.2015.06.060Get rights and content
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Highlights

  • Novel in-situ SEM test setup was found for mode II fracture analysis.

  • Novel imaging and post-processing steps were proposed.

  • Full displacement fields of delaminating composite interfaces were captured.

  • Displacement jumps were determined directly from displacement fields.

  • Further analysis of the data can lead to an experimentally determined cohesive law.

Abstract

A novel mode II fracture test setup based on a simple tensile loading scenario with a discontinuous ply specimen is proposed in the paper as the first step towards determination of the cohesive law of composite layer interfaces. Key outputs of the procedure are the full displacement fields obtained by correlation of high resolution SEM images taken during in-situ tensile tests. Analysis of the full displacement fields at subsequent stress levels allow for unique analysis of the damage zone and direct determination of the displacement jumps across the interface. The next phase of the work is the evaluation of the shear stresses at the interface necessary to determine the cohesive law.

Abbreviations

3PB
three point bending
COD
crack opening displacements
DCB
double cantilever beam
DIC
digital image correlation
EB
electron beam
ENF
end notched flexure
LVDT
linear variable differential transformers
MMB
mixed mode bending
SEM
scanning electron microscope
UD
unidirectional
VCCT
virtual crack closure technique

Keywords

Composites
Cohesive zone modelling
Delamination
In-situ SEM testing

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