< Back to previous page

Publication

Fibre-direction strain measurement in a composite ply under quasi-static tensile loading using Digital Volume Correlation and in situ Synchrotron Radiation Computed Tomography

Journal Contribution - Journal Article

Digital Volume Correlation (DVC), in concert withinsituSynchrotron Radiation Computed Tomography (SRCT),has been applied to Carbon-Fibre Reinforced Polymers (CFRPs) under quasi-static tensile loading. DVC re-presents a relatively novel tool for quantifying full-field volumetric displacements and implicit strain fields. Thehighly 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 fibredirection. To permit the application of DVC to displacement and/or strain measurements parallel to the fibreorientation, the matrix was doped with a sparse population of sub-micrometre barium titanate particles to act asdisplacement trackers (i.e.fiducial markers). For the novel materials systems we have developed, measurementnoise is considered along with the spatial filtering intrinsic to DVC data processing. Compared to volume imagesacquired through Micro-focus Computed Tomography (μCT), hold-at-load artefacts are mitigated through scantimes on the order of seconds using SRCT, as opposed to hours. Instances of individually fractured fibres evolvinginto clusters of breaks are presented, together with the associated strain redistribution (imaged at a voxel re-solution of 0.65 μm). It is shown that the distance over which strain is recovered in the broken fibres not onlyincreases with the applied force, but also with the number of broken fibres, delineating aspects of the loadshedding phenomenon. The study demonstrates that unprecedented, mechanistically-consistent three-dimen-sional (3D) strain measurements may be made in relation to fibre failure events, that can be used to validatemicromechanical models for predicting UD tensile failure. We believe this work presents the first application ofDVC to the SRCT imaging of failure in CFRPs, achieving significantly higher resolution than reported previouslywithin the literature.
Journal: Composites A, Applied Science and Manufacturing
ISSN: 1359-835X
Volume: 137
Publication year:2020
BOF-keylabel:yes
IOF-keylabel:yes
BOF-publication weight:10
CSS-citation score:1
Authors:International
Authors from:Higher Education
Accessibility:Open