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Answer:
L 1 s 4 =
3
6
(a)
e 4 () =
L 1
=
1
1
a 3
(b) e 4
() =
(
sin a
a
)
(
)
s 2
s 2
a 2
L 1
=
1
1
a 3
(c)
e 4 () =
(
a
sin a
)
(
)
s 2
s 2
+
a 2
1
1
2 a 3
L 1
(d) e 4
() =
=
(
sinh a
sin a
)
s 4
a 4
1
1
4 a 4
L 1
(e)
e 4
() =
=
(
cosh a
sin a
sinh a
cos a
)
s 4
+
a 4
4.20 Find the initial parameters for a transfer matrix solution of a beam that is simply
supported on both ends.
Answer:
0
b
LM b /(
M b /
w
=
M 0
=
0 ,
θ
= w
/
L
+
6 EI
)
,
0
=−
L
0
0
=
(
+
/).
4.21 Suppose a beam has a variable moment of inertia I
Place the governing
differential equations in first order form. Integrate these equations to find an expres-
sion for the state of variables at position x . That is, find the transfer matrix for this
beam.
I 0
1
x
Hint:
A is not constant.
b , V b , and M b for a transfer matrix of a beam element
with a parabolically distributed applied loading.
4.23 The Runge-Kutta method is a numerical integration technique for the solution of
initial value problems. For the system of differential equations
z 1 =
0
0
4.22 Find the loading functions
w
b ,
θ
f 1
(
x, z 1 ,z 2
)
z 2 =
f 2
(
x, z 1 ,z 2
)
with the initial values z 1 (
x 0 ) =
z 1 , 0 and z 2 (
x 0 ) =
z 2 , 0 , one Runge-Kutta approximation
for moving one step (0 to h )is
1
6 (
z 1 , 1 =
z 1 , 0 +
k 1 +
2 k 2 +
2 k 3 +
k 4 )
1
6 (
=
+
+
+
3
+
4
)
z 2 , 1
z 2 , 0
2
2
1
2
with
k 1
=
(
)
1
=
(
)
hf 1
x 0 ,z 1 , 0 ,z 2 , 0
hf 2
x 0 ,z 1 , 0 ,z 2 , 0
hf 1 x 0
hf 2 x 0
h
2 ,z 1 , 0
k 1
2
+
h
2 ,z 1 , 0
k 1
2
+
1
2
1
2
=
+
+
2
=
+
+
k 2
,z 2 , 0
,z 2 , 0
hf 1 x 0
hf 2 x 0
h
2 ,z 1 , 0
k 2
2
+
h
2 ,z 1 , 0
k 2
2
+
2
2
2
2
=
+
+
3
=
+
+
k 3
,z 2 , 0
,z 2 , 0
=
(
+
+
+
)
4
=
(
+
+
+
)
k 4
hf 1
x 0
h, z 1 , 0
k 3 ,z 2 , 0
hf 2
x 0
h, z 1 , 0
k 3 ,z 2 , 0
3
3
As an example, integrate the beam equations
w
w
0
0
10 0
000 1
EI
000 0
001 0
θ
θ
0
d
dx
=
+
V
M
V
M
p z (
x
)
0
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