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Unformatted text preview: Sec_2.8-2.12.qxd 212 9/25/08 11:43 AM Page 212 CHAPTER 2 Axially Loaded Members Impact Loading
The problems for Section 2.8 are to be solved on the basis of the assumptions
and idealizations described in the text. In particular, assume that the material
behaves linearly elastically and no energy is lost during the impact. Collar Problem 2.8-1 A sliding collar of weight W 150 lb falls from a height
h 2.0 in. onto a flange at the bottom of a slender vertical rod (see figure).
The rod has length L 4.0 ft, cross-sectional area A 0.75 in.2, and modulus
of elasticity E 30 106 psi.
Calculate the following quantities: (a) the maximum downward
displacement of the flange, (b) the maximum tensile stress in the rod,
and (c) the impact factor. L Rod
Flange Probs. 2.8-1, 2.8-2, 2.8-3 Solution 2.8-1 Collar falling onto a flange
(a) DOWNWARD DISPLACEMENT OF FLANGE
EA dst 0.00032 in. Eq. of (2-53):
dmax dst c 1 + a 1 +
0.0361 in. 2h 1/2
dst ; (b) MAXIMUM TENSILE STRESS (EQ. 2-55)
L 22,600 psi ; (c) IMPACT FACTOR (EQ. 2-61)
E Impact factor 150 lb
6 10 psi A 4.0 ft 48 in.
2 0.75 in. dmax
113 0.0361 in.
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- Fall '11