Biomedical Engineering Reference
In-Depth Information
and
ε
0
ε
1
ε
0
ε
1
ε
0
ε
1
−
5
−
1
AAAAAA
10
======
sec,
rr
rr
zz
zz
rz
rz
E
0
E
1
−
15
−
1
−
15
−
1
AA
== =
10
Vm/
sec
10
N
C/
sec
r
r
E
0
E
1
−
8
GG
=
=×
15
.
10
/(Ampere sec)
⋅
r
r
The initial inner and outer radii are assumed to be
a
0
= 25 mm,
b
0
= 35 mm
and
e
0
= 0 is assumed. In the calculation,
u
r
(
t
) <<
a
0
has again been assumed for
the sake of simplicity; that is,
a
(
t
) and
b
(
t
) may be approximated by
a
0
and
b
0
.
To illustrate the devolution process, we investigate the change of the
volume fraction of bone matrix material from its reference value, which is
denoted by
e,
in the transverse direction at several specific times. We also
distinguish three loading cases to investigate the influence of electric, mag-
netic, and thermal loads on the bone structure. Finally, the effect on the bone
of coupling electric and mechanical loads is studied.
• Case 1:
p
(
t
) = 0,
P
= 1500 N,
T
0
(
t
) = 0°C, φ
b
− φ
a
= 30V, ψ
b
− ψ
a
= 0.
• Figure 3.9 shows the variation of
e
with time
t
in the transverse
direction of bone for the electric loading described previously.
It can be seen from the figure that as time passes, the initially
0
1 day
2 days
5 days
10 days
20 days
30 days
50 days
75 days
100 days
0.008
0.006
e
0.004
0.002
0.000
0.026
0.028
0.030
0.032
0.034
0.036
r
(
m
)
FIGURE 3.9
Variation of
e
with time
t
along the radii for electric load.
