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sm8 82

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PROBLEM (8.82) A compressed-air tank of uniform thickness t = 5-mm is subjected to an internal
pressure of p = 1.4 MPa (Fig. P8.77). Determine the maximum axial and circumferential stresses.
SOLUTION
∑F
axial
= 0 : σ a ⋅ Aw = p ⋅ A
where A = projected inside area
Aw =cross-sectional area of tank
or
σ a [250 + 150π ](5)2
1.5 mm
= 1.4(106 )[250 × 300 + π (150) 2 ]
L
from which
A
p
σt
0.15 m
∑F
vertical
p
0.25 m
σa
Aw
σt
σ a = 28.3 MPa
The maximum
circumferential
stress occurs on
the sides.
0.15 m
= 0 : 2(5) L ⋅ σ c = p (250 + 300) L
or
1.4 × 106 (550)
= 77 MPa
σt =
2(5)
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