Biomedical Engineering Reference
In-Depth Information
Q
M
2
(6.7)
I
(
I
I
)sin
Re
I
Gxy
(
,
)
G
max
G
min
(
xy
,
)
G
min
G
I
Gmin
is the minimum green light intensity between all pixels
of
N
2
,
I
G
max
the maximum green light intensity between all pixels of
N
3
, and
M
G
= 538 nm the green light wavelength. We consider
F
a
collection of images (
F
i
with
i
and with same dimensions than
N
1
) where photoelastic effect is visible. To calculate retardation
Re
(
x
,
y
)
in pixel (
x
,
y
) of
F
i
we used Eq. (6.7) where
I
G
(
x
,
y
)
is the intensity
of green registered at pixel (
x
,
y
) of
F
i
. We obtain optical path length
D
(
x
,
y
)
from pixel (
x
,
y
) of
N
1
(for photoelastic coeficient calibration,
refer to Chapter 4) and using Eq. 6.8, we calculate the magnitude of
principal stress component (
T
1
-
T
2
)
(
x
,
y
)
in pixel (
x
,
y
) of
F
i
.
ℕ
Re
(,)
xy
TT
(
)
(6.8)
1
2
(
xy
,
)
x
DC
(,)
Camera
Hybrid Pump
Controller
Stress
Analysis
Software
Vasculature
Model
Figure 6.7
Experimental setup for photoelastic stress analysis on the
vasculature model wall membrane while human blood pressure
is simulated within the model.
Stress was measured for eight images:
N
2
for reference,
F
a
collection of ive video frames captured when the hybrid pump was
circulating luid through the model (
N
3
=
F
3
), and
N
4
,
N
5
are pressure
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