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Fibre-direction strain measurement in a composite ply under quasi-static tensile loading using digital volume correlation and in situ synchrotron radiation computed tomography

Fibre-direction strain measurement in a composite ply under quasi-static tensile loading using digital volume correlation and in situ synchrotron radiation computed tomography
Fibre-direction strain measurement in a composite ply under quasi-static tensile loading using digital volume correlation and in situ synchrotron radiation computed tomography
Digital Volume Correlation (DVC), in concert with in situ Synchrotron Radiation Computed Tomography (SRCT), has been applied to Carbon-Fibre Reinforced Polymers (CFRPs) under quasi-static tensile loading. DVC represents a relatively novel tool for quantifying full-field volumetric displacements and implicit strain fields. The highly anisotropic and somewhat regular/self-similar microstructures found in well-aligned unidirectional (UD) materials at high volume fractions are shown to be intrinsically challenging for DVC, especially along the fibre direction. To permit the application of DVC to displacement and/or strain measurements parallel to the fibre orientation, the matrix was doped with a sparse population of sub-micrometre barium titanate particles to act as displacement trackers (i.e. fiducial markers). For the novel materials systems we have developed, measurement noise is considered along with the spatial filtering intrinsic to DVC data processing. Compared to volume images acquired through Micro-focus Computed Tomography (μCT), hold-at-load artefacts are mitigated through scan times on the order of ∼seconds using SRCT, as opposed to ∼hours. Instances of individually fractured fibres evolving into clusters of breaks are presented, together with the associated strain redistribution (imaged at a voxel resolution of 0.65 μm). It is shown that the distance over which strain is recovered in the broken fibres not only increases with the applied force, but also with the number of broken fibres, delineating aspects of the load shedding phenomenon. The study demonstrates that unprecedented, mechanistically-consistent three-dimensional (3D) strain measurements may be made in relation to fibre failure events, that can be used to validate micromechanical models for predicting UD tensile failure. We believe this work presents the first application of DVC to the SRCT imaging of failure in CFRPs, achieving significantly higher resolution than reported previously within the literature.
Carbon-Fibre Reinforced Polymers (CFRPs),, Microstructures, Micromechanics, Synchrotron Radiation Computed Tomography (SRCT), Digital Volume Correlation (DVC), Strain mapping
1359-835X
Schoberl, Erich
d2b5dc9a-b340-47bd-874c-bdbcc6b499da
Breite, C.
ffafe786-b374-4ab5-9859-d547d17bfd8f
Melnikov, A.
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Swolfs, Y.
d346a5b6-6d57-4e5e-b8e1-1b02a73d00eb
Mavrogordato, Mark
f3e0879b-118a-463a-a130-1c890e9ab547
Sinclair, Ian
6005f6c1-f478-434e-a52d-d310c18ade0d
Spearing, Mark
9e56a7b3-e0e8-47b1-a6b4-db676ed3c17a
Schoberl, Erich
d2b5dc9a-b340-47bd-874c-bdbcc6b499da
Breite, C.
ffafe786-b374-4ab5-9859-d547d17bfd8f
Melnikov, A.
7166dc99-f56c-4cf5-8417-5f89d4e1ed8d
Swolfs, Y.
d346a5b6-6d57-4e5e-b8e1-1b02a73d00eb
Mavrogordato, Mark
f3e0879b-118a-463a-a130-1c890e9ab547
Sinclair, Ian
6005f6c1-f478-434e-a52d-d310c18ade0d
Spearing, Mark
9e56a7b3-e0e8-47b1-a6b4-db676ed3c17a

Schoberl, Erich, Breite, C., Melnikov, A., Swolfs, Y., Mavrogordato, Mark, Sinclair, Ian and Spearing, Mark (2020) Fibre-direction strain measurement in a composite ply under quasi-static tensile loading using digital volume correlation and in situ synchrotron radiation computed tomography. Composites Part A: Applied Science and Manufacturing. (doi:10.1016/j.compositesa.2020.105935).

Record type: Article

Abstract

Digital Volume Correlation (DVC), in concert with in situ Synchrotron Radiation Computed Tomography (SRCT), has been applied to Carbon-Fibre Reinforced Polymers (CFRPs) under quasi-static tensile loading. DVC represents a relatively novel tool for quantifying full-field volumetric displacements and implicit strain fields. The highly anisotropic and somewhat regular/self-similar microstructures found in well-aligned unidirectional (UD) materials at high volume fractions are shown to be intrinsically challenging for DVC, especially along the fibre direction. To permit the application of DVC to displacement and/or strain measurements parallel to the fibre orientation, the matrix was doped with a sparse population of sub-micrometre barium titanate particles to act as displacement trackers (i.e. fiducial markers). For the novel materials systems we have developed, measurement noise is considered along with the spatial filtering intrinsic to DVC data processing. Compared to volume images acquired through Micro-focus Computed Tomography (μCT), hold-at-load artefacts are mitigated through scan times on the order of ∼seconds using SRCT, as opposed to ∼hours. Instances of individually fractured fibres evolving into clusters of breaks are presented, together with the associated strain redistribution (imaged at a voxel resolution of 0.65 μm). It is shown that the distance over which strain is recovered in the broken fibres not only increases with the applied force, but also with the number of broken fibres, delineating aspects of the load shedding phenomenon. The study demonstrates that unprecedented, mechanistically-consistent three-dimensional (3D) strain measurements may be made in relation to fibre failure events, that can be used to validate micromechanical models for predicting UD tensile failure. We believe this work presents the first application of DVC to the SRCT imaging of failure in CFRPs, achieving significantly higher resolution than reported previously within the literature.

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Accepted/In Press date: 2 May 2020
e-pub ahead of print date: 16 May 2020
Keywords: Carbon-Fibre Reinforced Polymers (CFRPs),, Microstructures, Micromechanics, Synchrotron Radiation Computed Tomography (SRCT), Digital Volume Correlation (DVC), Strain mapping

Identifiers

Local EPrints ID: 441042
URI: http://eprints.soton.ac.uk/id/eprint/441042
ISSN: 1359-835X
PURE UUID: 1606a1fc-c746-459c-bd1a-b39afb6ead1c
ORCID for Mark Spearing: ORCID iD orcid.org/0000-0002-3059-2014

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Date deposited: 28 May 2020 16:57
Last modified: 07 Oct 2020 01:49

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