sm11 34

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PROBLEM (11.34) The jib crane of Fig. P11.34a is constructed of a 35-mm-diameter rod
BC and a steel tube AB. The approximate stress-strain curve for both members is shown in
P11.34b. Determine the value of W at which failure occurs.
Given: The steel tube has the following properties:
A = 400 mm2 , I = 8x103 mm4 , E = 200 GPa.
SOLUTION
2
BC
FW=
AB
FW
=
Rod BC
6
2 5 10 ( 0.035 )
4
W2
π
=× ×
N
4,811=
or
3.4Wk
=
Bar AB
66
8 10 (400 10 ) 3.2
y
PkN
−
=× × =
299
2
(200 10 )(8 10 ) 2.53
(2.5)
cr
WP kN
π
−
××
== =
and
6
2530 6.325 8
400 10
cr
M
Pa MPa σ
−
== <
×
Conclusion: bar AB fails as a column, and Wk2.53
all N
=
2.5 m
B
d
=
35 m
45o
Rod
1
1
C
A W
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