Biomedical Engineering Reference
In-Depth Information
Fig. 5.2
Model validation using experimental data by Herlihy and Murphy (
1973
) obtained from
medial strips (
Θ
strip
85
.
5
◦
): (
a
) force-stretch response from experiment and model and (
b
) results
of the finite element simulation. Deformed shape and von Mises stress distribution at
λ
strip
=
1
.
2
=
5.3.1 Model Validation
For the model validation active and passive tension experiment performed on
porcine medial strips (Herlihy and Murphy,
1973
) have been used, see Fig.
5.2
(a).
Following the experimental protocol, the porcine strips have been completely acti-
vated so that a temporally converged contraction process is existent. Two main ori-
entations (
Θ
s
,
1
/
2
=±
4
.
5
◦
) of SMC layers with equal SMC fractions (
f
s
,
1
/
2
=
0
.
5)
have been measured. Strips with dimensions
h/w/t
=
8
.
0
/
1
.
3
/
1
.
0 mm have been
dissected along the SMCs alignment, namely
Θ
strip
=
85
.
5°. According to the ex-
perimental boundary conditions in Herlihy and Murphy (
1973
) we approximate
them by fixing both ends of the strip in all directions. For the collagen dispersion of
porcine, medial tissue experimental data by Dahl et al. (
2007
) have been used. The
values for the rate constants of the chemical model have been taken from Hai and
Murphy (
1988
) as these are rooted on data obtained by Singer and Murphy (
1987
)
investigating swine tissue as well. Hence, a consistent parameter set is created, see
Table
5.1
.
Figure
5.2
(a) indicates that the proposed model accurately captures the force-
stretch behavior. As the tissue strip is aligned with the loading direction in the strips
long axis high stress values can be identified, see Fig.
5.2
(b).
5.3.2 Muscle Tissue Strip
In order to show the ability of the model a three-dimensional tissues example, dis-
sected from vessels is used, see Fig.
5.3
. The strip is characterized by two layers,
