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expressed as
w 0 +
w 0 +
w L +
w L =
w T N u
N u
=
w(
x
) =
H 1
w
+
H 2
H 3
H 4
w
+
H 5
H 6
w
(10)
0
L
w
= w |
w
= w |
with
L , etc. Chapter 4, Section 4.4.2 may be helpful in understanding
the use of Hermitian polynomials. Expressions for H j
i
0 ,
0
x
=
L
x
=
can be found in
standard references or derived using the procedures of Chapter 4. Because of the boundary
conditions of the beam (Fig. 7.1),
as functions of
ξ
w
= w 0 = w
= w L =
.
0
Thus,
0
L
H 3 w 0 +
H 5 w L =
w T N u
w =
N u
w
=
(11)
with
1
2 ξ
5
3
2 ξ
3
2 ξ
1
2 ξ
2
3
4
3
4
5
N u =
+
(
4
ξ
+
7
ξ
3
ξ
)
w 0
w L
w
=
Insertion of (11) into (2) leads to the system of equations for
w ,
L 3 34
1
p 0 L
EI
/
6
w
=
(12)
4
192
8
/
6
which has the solution
p 0 L 4
120 EI [8
1] T
w
=
(13)
Substitution of this expression in (11) gives
p 0 L 4
120 EI (
2
3
4
5
w =
4
ξ
8
ξ
+
5
ξ
ξ
)
(14)
The results can be compared with the exact solution, which has been derived several
times in this work.
A. Exact solution:
p 0 L 4
120 EI (
2
3
4
5
w =
4
ξ
8
ξ
+
5
ξ
ξ
)
(15)
B. Trial deflection with m
=
1:
p 0 L 4
108 EI (
2
3
4
w =
3
ξ
5
ξ
+
2
ξ
)
(16)
C. Trial deflection with m
=
2:
p 0 L 4
120 EI (
2
3
4
5
w =
4
ξ
8
ξ
+
5
ξ
ξ
)
(17)
D. Trial deflection based on fifth degree Hermitian polynomials:
p 0 L 4
120 EI (
2
3
4
5
w =
4
ξ
8
ξ
+
5
ξ
ξ
)
(18)
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