Title: Precise determination of the Poisson ratio in soft materials with 2D digital image correlation
Authors: Pritchard, Robyn ×
Lava, Pascal
Debruyne, Dimitri
Terentjev, Eugene #
Issue Date: 2013
Publisher: Royal Society of Chemistry
Series Title: Soft Matter vol:9 issue:26 pages:6037-6045
Abstract: In this article, we demonstrate the application of digital image correlation (DIC) in evaluating the strains
and Poisson ratio of a range of soft materials in terms of their spatial and temporal resolutions. Four samples
of Polydimethylsiloxane (PDMS) were used as control substances and were measured to have Poisson ratios
of 0.498, 0.503, 0.500, and 0.499, in agreement with the reported incompressible value of 0.50 [1]. Two
carbon nanotube (CNT) elastomers of identical composition, but one of a homogeneous and the other of an
inhomogeneous CNT distribution, were used to determine the spatial resolution with good results (Fig. 2
and Fig. 4). The relaxation of a 3D polydomain liquid crystal elastomer (3D-LCE), a cholesteric liquid
crystal elastomer (CLCE), and a polyacrylamide gel (PAAm) in water, were used to determine the temporal
resolution. A 10min video short at 25fps was used to evaluate the time dependence of the 3D-LCE over
which time an increase in the Poisson ratio was observed. The 3D-LCE relaxes from its initial state at 0.42
to 0.50, converging towards incompressibility. The CLCE was found to have a similar initial value of 0.44
but converged to
60, a consequence of its anisotropic nature. PAAm gel relaxation in water was studied
over a time period of 7 hours with digital images taken periodically every minute. Its Poisson ratio was
found to decrease smoothly from 0.50 to 0.26, with an accompanying reduction in force. The equilibrium
result compares well to the 0.25 value predicted by theories of the strain induced swelling of dilute gels. In
summary, we nd DIC to be a powerful and easy to implement method of accurately measuring local strains
in a range of soft materials
ISSN: 1744-683X
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Department of Materials Engineering - miscellaneous
Technologiecluster Materialentechnologie
Materials Technology TC, Technology Campuses Ghent and Aalst
× corresponding author
# (joint) last author

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