ENGN.2060 Lecture Notes - Lecture 4: Ferrari 250
13 Jun 2018
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96
PROBLEM 2.4
Two gage marks are placed exactly 250 mm apart on a 12-mm-diameter aluminum rod with E = 73 GPa and
an ultimate strength of 140 MPa. Knowing that the distance between the gage marks is 250.28 mm after a load
is applied, determine (a) the stress in the rod, (b) the factor of safety.
SOLUTION
(a) 0
LL
G
250.28mm250mm
0.28mm
0
G
H
L
0.28 mm
250 mm
4
1.11643 10
u
V
H
E
94
(73 10 Pa)(1.11643 10 )
u u
7
8.1760 10 Pa u
81.8 MPa
V
W
(b) F.S. u
V
V
140 MPa
81.760 MPa
1.71233 F.S. 1.712 W
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Document Summary
Two gage marks are placed exactly 250 mm apart on a 12-mm-diameter aluminum rod with e = 73 gpa and an ultimate strength of 140 mpa. Knowing that the distance between the gage marks is 250. 28 mm after a load is applied, determine (a) the stress in the rod, (b) the factor of safety. 4 (cid:86) (cid:72)(cid:32) e (73 10 pa) (1. 11643 10 ) (cid:117) A square yellow-brass bar must not stretch more than 2. 5 mm when it is subjected to a tensile load. Gpa and that the allowable tensile strength is 180 mpa, determine (a) the maximum allowable that length of the bar, (b) the required dimensions of the cross section if the tensile load is 40 kn. 3 (105 10 )(2. 5 10 ) (cid:117) (cid:117) 6 (190 10 )(12. 566 10 ) (cid:117) (cid:117) 3 (12. 566 10 )(200 10 )(6 10 ) (cid:117) (cid:117) (cid:16) Bc (cid:32) (0. 9509)(2. 091 10 ) 1. 988 10 n (cid:117)
