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An Investigation on the use of Silicone to Model Arterial Tissue Behaviour in
the Carotid Bifurcation
Mulvihill, J.J., O'Donnell, M. R., O'Connell, B. M. and Walsh, M.T.
Centre of Applied Biomedical Engineering Research, Dept. of Mechanical, Aeronautical and
Biomedical Engineering and The Materials and Surface Science Institute, University of Limerick
john.mulvihill@ul.ie
Abstract
This paper presents the investigation of an analogue
material to represent arterial tissue behaviour. This
study computationally compares the mechanical
behaviour of arterial tissue and a silicone material
model in an idealised carotid bifurcation model. Results
demonstrate that silicone does not have similar
mechanical behaviour as arterial tissue under a normal
physiological pressure load.
1. Introduction
The development of atherosclerosis in the carotid
bifurcation (CB) of the cardiovascular system has been
the subject of much investigation. The CB is a prevalent
area for atherosclerotic plaque build-up. Bhardvajet al.
[1] dimensioned an idealised ‘Y’ shape model of the
CB, which is the gold standard of dimensions for the
CB in numerical studies (Haritonet al. [2]). However,
Smith et al. [3] developed an updated CB idealised
geometry that better represents the CB called the tuning
fork model. A study by Thomas et al. [4] illustrated and
validated the improvements in this model.
Experimentally, silicone material is used primarily to
mimic the mechanical behaviour of arterial tissue. This
study aims to compare the mechanical behaviour of
silicone material to arterial tissue using finite element
analysis (FEA). These materials will be applied to the
idealised CB tuning fork model.
2. Material and Methods
The numerical model was developed using FEA to
model the mechanical behaviour of a silicone material
and compare this material behaviour to the carotid
arterial tissue. The silicone material was modelled using
a reduced polynomial strain energy function (SEF)
characterised and validated by Corbett et al. [5].The
arterial tissue material model was applied using a SEF
developed by Gasser et al., (HGO) [6]. This HGO SEF
is a histological and phenomenological SEF that
includes the effect of collagen fibres within the
tissue.To determine if the HGO SEF does represent the
mechanical behaviour of the carotid arterial tissue, and
whether silicone behaves similarly, the numerical
results are compared to the biaxial mechanical
properties of common carotid arteries from Sommer et
al., (2010) [7].
3. Results
The HGO SEF is compared to experimental data on
the mechanical properties of carotid tissue from
58
Sommer et al. [7] as seen in figure 1. This was carried
out to validate the HGO SEF and confirm that it
predicts the arterial tissue behaviour.
Figure 1 illustrates that the HGO SEF is comparable
to experimental data under the same pressure loads.
There is a difference in material behaviour after a 7%
circumferential stretch. Figure 1 also compares the
HGO SEF material behaviour to the silicone model
showing a significant difference in mechanical
behaviour between the material models.
Figure 1:Plot of pressure against the circumferential stretch
of the external radius for, the HGO SEF, Silicone SEF and the
Sommer et al., (2010) [7] carotid artery properties
4. Discussion
The results from this study confirm that the HGO
SEF is a good representation of arterial tissue to
published experimental material properties, even when
applied to a complex geometry such as the carotid
bifurcation. The results from the numerical models
illustrate the difference in mechanical behaviour
between the silicone and arterial tissue. Silicone does
not represent arterial tissue mechanical behaviour
undergoing a pressure load. Therefore questions arise as
to whether silicone is truly an analogous material of
arterial tissue.
5. References
[1]Bhardvaj, B. K., Mabon, R. F. &Giddens, D. P. (1982).
Journal of Biomechanics. 15: 363-365, 367-378.
[2] Hariton, I., Debotton, G., Gasser, T. & Holzapfel, G.
(2007). Bio.and Modelling in Mechanobiology. 6: 163-175.
[3] Smith, R. F. (1996). Academic Radiology. 3: 898-911.
[4] Thomas, J. B..(2005). Stroke. 36: 2450-2456.
[5] Corbett, T. J. &McGloughlin, T. M. (2010). Journal of
Biomechanical Engineering. 132: 011008-9.
[6] Gasser, T. C., Ogden, R. W. & Holzapfel, G. A. (2006).
Journal of The Royal Society Interface. 3: 15-35.
[7] Sommer, G., Reitnig, P., Koltringer, L. & Holzapfel, G. A.
(2010). Am J Physiol Heart Circ Physiol. 298: H898-912.