Biomedical Engineering Reference
In-Depth Information
the catheter stiffness and lumen, reducing the range of tools that
may be evaluated or used for evaluation.
Endovascular
Surgery
Simulator
5
mm
a)
b)
Figure 4.1
(a) Endovascular surgery simulator. (b) Birefringence
consequence of stress applied to the vasculature model by a
guide wire. See also Color Insert.
4.1
Photoelastic Stress Analysis Fundamental
Equations
The resulting phase shift of polarized light while passing through
photoelastic materials is called retardation and its variation is
described by
¥
22
2
µ
(
1
v
) (
TT
TT
)
1
1
2
2
¦
¦
¦
¦
¶
¶
¶
¶
¥
§
¦
Re
µ
·
¶
2
2
(
1
2
v
vvv
)(
)
(4.1)
3
23
cD
2
2
2
(
)
(
TTTT
1
)(
)
§
·
2
3
1
2
2
3
where Re is the retardation and is measured in nanometers,
D
is the
optical path length (thickness of the photoelastic material),
c
is the
photoelastic coeficient of the photoelastic material,
v
1
,
v
2
and
v
3
are
the components of the unitary vectors that describe the light beam
direction in terms of the principal stresses
T
1
,
T
and the radial stress
2
component
T
3
as described in [3] (Fig. 4.2a).
When the principal stress plane is parallel to the light beam,
v
1
=
-cos
K
=
sin
K
v
2
and
v
3
=
0, then
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