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Unformatted text preview: 05Ch05.qxd 9/24/08 396 4:59 AM Page 396 CHAPTER 5 Stresses in Beams (Basic Topics) Problem 5.5-6 A freight-car axle AB is loaded approximately as shown in
the figure, with the forces P representing the car loads (transmitted to the axle
through the axle boxes) and the forces R representing the rail loads (transmitted
to the axle through the wheels). The diameter of the axle is d 80 mm, the
distance between centers of the rails is L, and the distance between the forces
P and is R is b 200 mm.
Calculate the maximum bending stress smax in the axle if P 47 kN. P P
B A d d
b L Solution 5.5-6
d 82 mm P pd4
64 b 220 mm smax 50 kN I MAX. BENDING STRESS Mmax I
Pb 2.219 * 10
Mmax 6 m4 Md
2I smax 203 MPa ; 11 kN # m Problem 5.5-7 A seesaw weighing 3 lb/ft of length is occupied by two
children, each weighing 90 lb (see figure). The center of gravity of each
child is 8 ft from the fulcrum. The board is 19 ft long, 8 in. wide, and
1.5 in. thick.
What is the maximum bending stress in the board? Solution 5.5-7 Seesaw
b 8 in. h 1.5 in. q 3 lb/ft P 90 lb d 8.0 ft L 2 Pd + Mmax qL
2 720 lb-ft + 135.4 lb-ft
855.4 lb-ft 10,264 lb-in. 2 S
6 3.0 in.3.
S 10,264 lb-in.
3.0 in.3 3420 psi ; 9.5 ft ...
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This note was uploaded on 12/22/2011 for the course MEEG 310 taught by Professor Staff during the Fall '11 term at University of Delaware.
- Fall '11