Biomedical Engineering Reference
In-Depth Information
Ty pical stress-strain curves for an ERI-S muscle
10
Dry ERI-S muscle
(Pt = 8.6%, H
2
O = 0%, membrane = 91.4%)
8
6
4
2
We t E R I-S Mus cle
(Pt = 7.5%, H
2
O = 12.5%,membrane = 80.0%)
0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Strain (%)
(w = 10.02 mm, t = 0.35 mm, L
eff
= 49.09 mm, and Pt loading ~3 mg/cm
2
)
(he cantilever beam method was used)
FIGURE 2.12
Effect of swelling on the stress-strain characteristics of IPMNCs.
10
We t E R I-S Muscle
(Pt = 7.5%, H
2
O = 12.5%, membrane = 80.0%)
8
Electric activation
2
6
4
3 V
2 V
Mechanical activation
1
2
1V
0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Strain (%)
FIGURE 2.13
Stiffening of IPMNCs due to placement in an electric field or under electric
activation.
is the stress tensor,
M
is the maximum moment at the built-in end, and
I
is the moment of inertia of the cross-section of the beam.
Thus, the moment
M
can be calculated based on the distributed load on the beam
or the applied electrical activation of the IPMNC beam. Having also calculated the
moment of inertia
I
, which for a rectangular cross-section of width
b
will be
I
=
bh
3
/12, the stress
where
σ
. The representative results are
plotted in figures 2.12 and 2.13. These figures include the effect of swelling and
stiffening behavior under electric activation. Here, electric activation refers to the
σ
can be related to the strain
ε
