Biomedical Engineering Reference
In-Depth Information
These equations are then solved for
F
and
F
1
, thus
T
and
F
1
T
F
ð
X
;
t
Þ¼
1
þ½r
o
u
ð
X
;
t
Þ
ð
x
;
t
Þ¼
1
½r
u
ð
x
;
t
Þ
:
(11.17)
The Lagrangian strain tensor
E
and the Eulerian strain tensor
e
are related to the
displacement gradients by substituting the two equations (
11.17
) into the two
equations (
11.15
), thus
T
T
E
¼
ð
1
=
2
Þf½r
o
u
ð
X
;
t
Þ
þ½r
o
u
ð
X
;
t
Þ þ ½r
o
u
ð
X
;
t
Þ½r
o
u
ð
X
;
t
g;
(11.18)
Þ
T
T
e ¼
ð
1
=
2
Þf½r uðx;
t
Þ
þ½ruðx;
t
Þ ½r uðx;
t
Þ½r uðx;
t
Þ
g:
(11.19)
The expanded component forms of (
11.18
) and (
11.19
) are given by
"
#
2
þ
2
2
E
II
¼
@
u
I
1
2
@
u
I
@
u
II
@
u
III
@
x
I
þ
þ
;
@
@
x
I
@
x
I
x
I
"
#
2
2
2
E
II II
¼
@
u
II
1
2
@
u
I
@
u
II
@
u
III
x
II
þ
þ
þ
;
@
@
x
II
@
x
II
@
x
II
"
#
;
2
2
2
E
III III
¼
@
u
III
1
2
@
u
I
@
u
II
@
u
III
x
III
þ
þ
þ
@
@
x
III
@
x
III
@
x
III
1
2
@
x
II
þ
@
u
I
u
II
x
I
þ
@
u
I
x
I
@
u
II
@
x
I
þ
@
u
II
@
@
u
II
x
II
þ
@
u
III
@
@
u
III
@
E
III
¼
;
(11.20)
@
@
@
x
I
@
x
I
x
II
@
x
III
þ
@
u
I
u
III
@
x
I
þ
@
u
I
x
I
@
u
III
@
x
I
þ
@
u
II
@
@
x
III
þ
@
u
II
u
III
@
@
u
III
1
2
E
I III
¼
;
@
@
x
I
@
x
I
@
x
III
1
2
@
x
III
þ
@
u
II
u
III
@
x
II
þ
@
u
I
@
x
III
þ
@
u
II
u
II
@
x
III
þ
@
u
II
u
III
@
@
u
III
E
II III
¼
;
@
@
x
II
@
@
x
III
@
x
II
@
x
III
and
"
#
2
þ
2
þ
2
e
11
¼
@
u
1
1
2
@
u
1
@
u
2
@
u
3
x
1
;
@
@
x
1
@
x
1
@
x
1
"
#
2
þ
2
þ
2
e
22
¼
@
u
2
1
2
@
u
1
@
u
2
@
u
3
x
2
;
@
@
x
2
@
x
2
@
x
2
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