Hoddy, B., Ahmed, N., Al-Lamee, K. et al. (3 more authors) (2021) Investigating the material modelling of a polymeric bioresorbable scaffold via in-silico and in-vitro testing. Journal of the Mechanical Behavior of Biomedical Materials, 120. 104557. ISSN 1751-6161
Abstract
The accurate material modelling of poly-l-lactic acid (PLLA) is vital in conducting finite element analysis of polymeric bioresorbable scaffolds (BRS) to investigate their mechanical performance and seek improved scaffold designs. To date, a large variety of material models have been utilised, ranging from simple elasto-plastic models to high fidelity parallel network models. However, no clear consensus has been reached on the appropriateness of these different models and whether simple, less computationally expensive models can serve as acceptable approximations. Therefore, we present a study which explored the use of different isotropic and anisotropic elasto-plastic models in simulating the balloon expansion and radial crushing of the thin-strut (sub-100 μm) ArterioSorbTM BRS using the Abaqus/Explicit (DS SIMULIA) solution method. Stress–strain data was obtained via tensile tests at two different displacement rates. The use of isotropic and transversely isotropic elastic theories was explored, as well as the implementation of stress relaxation in the plastic regime of the material. The scaffold performance was quantified via its post-expansion diameter, percentage recoil and radial strength. The in-silico results were validated via comparison with in-vitro data of an analogous bench test. Accurately predicting both the post-expansion scaffold shape and radial strength was found to be challenging using the in-built Abaqus models. Therefore, a novel user-defined material model was developed via the VUMAT subroutine which improved functionality by facilitating a variable yield ratio, dependent upon the plastic strain as well as stress relaxation in overly strained elements. This achieved prediction of the radial strength within 1.1% of the in-vitro results and the scaffold's post-expansion diameter within 6.7%. A realistic multi-balloon simulation strategy was also used which confirmed that a mechanism exists in the PLLA which facilitates the extremely low percentage recoil behaviour observed in the ArterioSorbTM BRS. This could not be captured by the aforementioned material property models.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2021 Elsevier. This is an author produced version of an article accepted for publication in Journal of the Mechanical Behavior of Biomedical Materials. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Stent / scaffold; Polymers; Finite element analysis; Material modelling |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Mechanical Engineering (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 11 Sep 2024 09:20 |
Last Modified: | 11 Sep 2024 09:20 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.jmbbm.2021.104557 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:217057 |