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Midterm

Exam-MECH3700-2009AprilExam


Department
Mechanical Engineering
Course Code
MECH 3700
Professor
All
Study Guide
Midterm

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MECH 3700 Principles
of
Manufacturing
Engineering A. Artemev
CARLETON UNIVERSITY
FINAL
EXAMINATION
April2009
Duration:
3 HOURS No.
of Students: 70
Department Name & Course
Number:
Mech. & Aero Engineering MECH 3700A
Instructor(s):
A. Artemev
AUTHORIZED
MEMORANDA:
CALCULATORS
ONLY
Students MUST count the number
of pages
in this examination question
paper
before
beginning to write and report any
discrepancy immediately
to a proctor.
This question
paper
has
5 pages.
This examination paper
MAY be taken from the
examination
room.
&
tt
a L-
/,'ri
All questions
have the
same
value.
Ansu,er
all
question.s.
l. The
maximum equilibrium
solubility
of hydrogen
at a partial
pressure
of I atm in liquid
magnesium
is26
cm3
per
100g.
It falls Io 18 cm3
per
l00gupon solidification.
The density
of
magnesium in
both liquid and
solid states is 1.14 g/cm3.
a) What would
be the
gas
porosity (volume
fraction
of gas
voids)
in the Mg casting if the
liquid metal were
saturated with hydrogen at a partial
pressure
of 0.7 atm in the gas
phase?
b) What
is the maximum parlial
pressure
of hydrogen
in contact with a liquid
alloy at
which
no
gas
porosity
is
produced
in
casting?
,/y
rry #tl''^'
/4@
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MECH 3700 Principles of Manufacturing
Engineering A. Artemev
2. Three
cylinders
were
made
of the same material.
All cylinders had the
same diameler
of 3 cm
and height
of 4.2 cm. High temperature axial compression
tests were performed
on all
cylinders
at the same temperature.
In all tests,
a very efficient lubrication
was used
that
completely
prevented
barreling
effects.
The
first
cylinder was
sub.iected
to the load
of 1 t
applied for the time
interval
of 1
min.The cylinder's
height
decreased
from
4.2
cm to2.15
cm.The
second cylinder was
subjected to the load
of 1.5 I applied
for
the
time
interval
of 0.5
ntin. Its height decreased
from 4.2
cm ro 2.05 cnt.
The third
cylinder rvas
subjected to the
load
of 0.75 t applied fbr
the time interval
of 1 .5
min. ,
a) Estimate
by calculation
the height of the third cylinder
after the deformation
if the
material
had the strain
rate sensitivity exponent
equal
to 0.5.
b) Comment briefly
on the expected
accuracy of the
obtained
height estimate.
3. 430 cm
long workpiece
is stretched
by
force
Fas shown in Fig.
1 until
cr:I5o. The original
cross-section
area of the workpiece
is 2.5 ,*'. Thr-
material
has a strain hardening curve
described
by:
o =36o.ro'42
MPo
Assume
that the ends of the workpiece
are
pin supporl
clamped
(i.e..
are free to rotate).
Assume
the
free
sliding
of the load application
point.
a). Find
the total work
done
during
stretching.
b). Find
the maximum
value
of cr that
can be reached
before
necking
begins.
2A
cm 10
crn
C{,
/
//
/a
/ 1.1
I)
a
j--L'.
-/
//{.-"*
.{T._.*
a
Fig. I
page
2
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