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ENSC 3313, Spring 2004
TEST 2  KEY
Name_________________________
Answer all 10 questions, show all work, 2points each
1. The loadelongation
plot for a tensile test specimen of gauge length 2 inches
and diameter 0.5 inches
is
shown.
Calculate the a) elastic modulus, b) yield strength, c) tensile strength, d) % elongation.
The cross sectional area
2
2
2
.
0
4
)
5
.
0
(
in
A
≈
=
π
.
Hence, stress=load/0.2 = 5
×
load
The gauge length = 2"; hence strain =
elongation/2.
a)
E ~ (5
×
7000)/(0.01/2) ~ 7.0
×
10
6
psi
b)
YS ~ 5
×
9,000 ~ 45,000 psi
c)
TS ~ 5
×
14,000 ~ 70,000 psi
d)
% elongation ~ (0.092/2)100 ~ 4.6%
2.
Shown is the plane (111) and the direction [
01
1
] in an aluminum FCC unit cell.
Calculate the resolved
shear stress in this slip system when 35MPa. is applied in the [001] direction.
Recall:
λ
φ
σ
τ
cos
cos
=
r
The resolved shear stress is given by the
formula:
cos
cos
=
r
Stress axis and plane normal:
3
1
cos
=
Stress axis and the slip direction:
2
1
cos
=
Resolved shear stress is:
408
.
0
6
=
=
r
=14.28MPa
x
y
z
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3.
A 10 mm diameter 70 Cu 30 Zn rod is to be drawn down to a 6mm diameter rod.
The final product must
have a tensile strength of above 450 MPa, a
hardness of less than 75, and a % elongation (50 mm) of at least
15%.
Specify a processing sequence.
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This note was uploaded on 01/10/2012 for the course ENSC 3313 taught by Professor Staff during the Fall '11 term at Oklahoma State.
 Fall '11
 staff

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