Di Leonardo, Sofia;
Monteleone, Alessandra;
Caruso, Patrizia;
Meecham-Garcia, Hugo;
Pitarresi, Giuseppe;
Burriesci, Gaetano;
(2024)
Effect of the apron in the mechanical characterisation of hyperelastic materials by means of biaxial testing: A new method to improve accuracy.
Journal of the Mechanical Behavior of Biomedical Materials
, 150
, Article 106291. 10.1016/j.jmbbm.2023.106291.
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Abstract
Biological soft tissues and polymers used in biomedical applications (e.g. in the cardiovascular area), are hyperelastic incompressible materials that commonly operate under multi-axial large deformation fields. Their characterisation requires biaxial tensile testing. Due to the typically small sample size, the gripping of the specimens commonly relies on rakes or sutures, where the specimen is punctured at the edges of the gauge area. This approach necessitates of an apron, excess of material around the gauge region. This work analyses the apron influence on the estimated mechanical response of biaxial tests performed by using a rakes gripping system, with the aim of verifying the test accuracy and propose improved solutions. In order to isolate the effect of the apron, avoiding the influence of anisotropy and inhomogeneity typical of most soft tissues, homogeneous and isotropic hyperplastic samples made from a uniform sheet of casted silicone were tested. The stress-strain response of specimens with different apron sizes/shapes was measured experimentally by means of biaxial testing and digital image correlation. Tests were replicated numerically, to interpret the experimental findings. The apron surrounding the gauge area acts as an additional annular constraint which stiffens the system, resulting in a significant overestimate in the stress values. This error can be avoided by introducing specific cuts in the apron. The study quantifies, for the first time, the correlation between the apron size/shape and the experimental stress overestimation, proposing a research protocol which, although identified on homogeneous hyperelastic materials, can be useful in providing more accurate characterisation of both, synthetic polymers and soft tissues.
| Type: | Article |
|---|---|
| Title: | Effect of the apron in the mechanical characterisation of hyperelastic materials by means of biaxial testing: A new method to improve accuracy |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.jmbbm.2023.106291 |
| Publisher version: | https://doi.org/10.1016/j.jmbbm.2023.106291 |
| Language: | English |
| Additional information: | Copyright © 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). |
| Keywords: | hyperelastic materials; soft tissues testing protocol; biaxial tensile testing; digital image correlation; non-linear finite element analysis, mechanical characterisation methods |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10182787 |
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