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sm11 46

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PROBLEM (11.46) Redo Prob. 11.45 for the case in which the tube fixed at its base and
free at its top, and has a factor of safety of n s = 2 (Fig. P11.43).
SOLUTION
Refer to Solution of Prob. 11.45. Here
Le = 2 L = 2(2.5) = 5 m (See Fig. 11.3a)
Le 5 × 103
=
= 217
r
23.05
Le
= 108.5
2r
(a) Equation (1) yields
⎡
⎛
σ max = (9.794) ⎢1 + (2.141) sec ⎜108.5
⎜
⎢⎣
⎝
= 38.2 kN
10 ×103
(1021)(210 × 103 )
⎞⎤
⎟⎥
⎟⎥
⎠⎦
(b) Equation (2) gives
⎡
⎛
⎞⎤
Py
⎢
1
(2.141)
sec
108.5
+
⎜
⎟⎥
3 ⎟
⎜
1021(10−16 ) ⎢
(1021)(210
10
)
×
⎝
⎠ ⎥⎦
⎣
Solving numerically, Py = 29.94 . Equation (11.22):
Py
250(106 ) =
Pall =
Py
ns
=
29.94
= 14.79 kN
2
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