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NAME:
________________________________
MATERIALS SELECTION
FALL SEMESTER
530.352
PROF. K.J. HEMKER
MIDTERM EXAMINATION
(Closed book  closed notes  open mind)
October 28
th
, 2002
1.
We have covered a number of different topics in class.
Briefly answer 5 out of the 6
questions
listed here.
Be sure to cross out the one that you do not want me to grade.
(5 points each; 25 points total)
i)
Describe the atomic structure of polymers like polystyrine; what is the basic
structure and how big is it?
Explain the difference between thermoset and
thermoplastic, between branched and crosslinked, and between T
glass
and T
melting
ii)
Draw and label the (121) plane.
Is there a <110>type direction [uvw] on this
plane?
If so, what is it? What is the <111>type direction on this plane?
x
y
z
530.352 Materials Selection
Midterm Exam 2002
Page 1 of 9
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cont.
(answer 5 out of 6)
iii)
You work for Ferrari and your boss would like you to design a new piston rod
such that it is both lightweight and does not buckle when loaded in compression.
You may assume that piston rod is cylindrical with a diameter of 6 mm and a
length of 25 cm and that the following relations hold:
m
=
π
r
2
l
ρ
P
buckling
=
2
EI
l
2
=
3
Er
4
4
l
2
Derive the [F][G][M] equation and give the materials index (M
1
) to minimize the
weight of the sticks.
iv)
One way to slow down dislocations and make a metal stronger is to add a second
element and make a solid solution alloy.
About how much solute is there in a
solid solution alloy?
Give the empirical relation for the solid solution
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 Spring '08
 Hemker

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