Information Technology Reference
In-Depth Information
3.34 Find the vertical displacement at point
b
of the truss of Fig. P3.34. The members are
made of the same material with the same areas.
FIGURE P3.34
A simple truss.
Answer:
V
=
9
.
5
P
/(
EA
)
N PR
3
3.35 Derive the deformation formula
V
for the stretching of a closely
coiled helical spring (Fig. P3.35).
J
is the polar moment of inertia of the cross-section
of the wire.
=
2
π
/(
GJ
)
FIGURE P3.35
Helical spring.
Hint:
Assume the displacement
V
of the spring is due only to the twisting of the
wire. If there are
N
active
co
ils, the total length of the wire being twisted is
(
2
π
R
)
N
.
The torque in the wire is
PR
.
U
i
=
M
t
L
/(
2
GJ
)
, where
M
t
is the torque.
Search WWH ::
Custom Search