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Unformatted text preview: 08Ch08.qxd 9/18/08 660 11:03 AM Page 660 CHAPTER 8 Applications of Plane Stress Problem 8.3-8 Solve the preceding problem if d 90 mm, F 42 kN, and tallow 40 MPa. Solution 8.3-8 Cylinder with internal pressure
Maximum shear stress (Eq. 8-10):
2t tmax F
2prt Minimum thickness:
d 90 mm r F 42.0 kN 45 mm
tallow Find minimum thickness tmin.
A Pressure in cylinder: p F
2pr tallow t min 40 MPa Substitute numerical values:
pr 42.0 kN
2p(45 mm)(40 MPa) t min 2 ; 3.71 mm Problem 8.3-9 A standpipe in a water-supply system (see figure) is 12 ft in
diameter and 6 inches thick. Two horizontal pipes carry water out of the
standpipe; each is 2 ft in diameter and 1 inch thick. When the system is
shut down and water fills the pipes but is not moving, the hoop stress at the
bottom of the standpipe is 130 psi.
(a) What is the height h of the water in the standpipe?
(b) If the bottoms of the pipes are at the same elevation as the bottom of the
standpipe, what is the hoop stress in the pipes? Solution 8.3-9 Vertical standpipe
(a) FIND HEIGHT h OF WATER IN THE STANDPIPE
p pressure at bottom of standpipe From Eq. (8-5): s1 pr
t or h Substitute numerical values:
h d 12 ft g 62.4 lb/ft3 s1 144 in. r 72 in. t 6 in. 62.4
1728 hoop stress at bottom of standpipe 130 psi (130 psi)(6 in.)
lb/in.3 b (72 in.)
25 ft ; gh 300 in. s1t
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