ch01-03 stress & strain & properties

01 Solutions 46060 5/6/10 2:43 PM Page 33
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•1–49. The beam is supported by a pin at A and a short
link BC. Determine the maximum magnitude P of the loads
the beam will support if the average shear stress in each pin
is not to exceed 80 MPa. All pins are in double shear as
shown, and each has a diameter of 18 mm.
C
30
P 4P 4P 2P
0.5m
0.5 m
1 m 1.5 m 1.5 m
B
A
a +©M A = 0; 2P(0.5) + 4P(2) + 4P(3.5) + P(4.5) - (T CB sin 30°)(5) = 0
T CB = 11P
: + ©F x = 0; A x - 11P cos 30° = 0
A x = 9.5263P
+ c ©F y = 0; A y - 11P + 11P sin 30° = 0
A y = 5.5P
F A = 2 (9.5263P) 2 + (5.5P) 2 = 11P
Require;
t = V A ; 80(106 ) = 11P>2
p
4 (0.018)2
P = 3.70 kN
Ans.
33