Nt1330 Final Exam
ME 3210
Woodruff School of Mechanical Engineering
Georgia Institute of Technology
Design, Materials, and Manufacture
1st Midterm Examination
Fall 2013
Note that multiple choices do NOT offer partial credits; check your calculations carefully.
1. Epoxy has density of 1.25 g/cm3 and elastic modulus of 4 GPa while Kevlar–49 has density of
1.5 g/cm3 and elastic modulus of 120 GPa. If a kelvar-49-reinforced epoxy composite is to have a transverse elastic modulus of 6.5 GPa, what should be its fiber volume fraction? (a) 65%, (b)
50%, (c) 40%, (d) 25%, (e) 10%. (3 points)
Your Answer: ___________
2. Which of the following regarding SPC is/are INCORRECT? (a) If the measuring resolution is
15% of the specified tolerance, the measurement …show more content…
is considered capable; (b) If the average of standard deviations of manufactured parts is 15% of the specified tolerance, the process would be considered capable; (c) If a manufacturing process has a process capability index of 110%, it would be considered capable; (d) If a manufacturing process has a process capability index of 65%, it would be considered incapable; (e) There is no way a manufacturing process is in control but is not capable. (4 points)
Your Answer: ____________
3. Parts A and B (in the left figure below) starting positions are random thus some
Which of the following is correct regarding for part B (tb) ? (a) 1.7 tb t a 1.3 tb ,
(e) (0.7)t b t a 0.3 t b . (3 points)
are to be inserted into the 3-pined base, while their hand orientation effort is needed before insertion. the orientation time for part A insertion (ta) and that
(b) 1.3 tb t a tb , (c) t a tb , (d) tb t a 0.7 tb ,
Your Answer: ____________
insertion
part B
Orientation time (s)
part A
3-pined
base
Manipulation by tweezers
Manipulation by hand
3
o
=360
2
1
o
180
o
360
o
180
o
0
0
0
100
200
(degree)
300
4. Name the process in the figure (a) centrifugal casting, (b) melt spinning, (c) crucible casting,
(d) rotational casting, (e) injection molding.
(3 points)
Your Answer: ____________ Gas
Crucible
Induction coil (for heating)
Melt
Strip (final product)
Copper disk
5. As a 10-kg of AISI1040 steel (plain carbon steel with 0.4% carbon) is cooled to 728oC, which statement is/are INCORRECT: (a) There is 5.05-kg austenite (); (b) There is 4.95-kg ferrite
(); (c) There is a 1.25-kg cementite (Fe3C); (d) The alloy is in a three-phase field of
Fe3C; (e) The alloy is 100% solid. (3 points)
Your Answer: ____________
6. An ellipsoid with major axes of 2", 3" and 4" is to be die cast in a graphite mold. The mold has a specific weight of 350 lbf/ft3 and outer dimensions of 6" by 6" by 6" as shown in the figure.
Note that the parting line of the mold lies on the plane of maximum cross-section of the casting.
In this case a clamping force of 7.3 lbf is needed to keep the mold haves from separation.
Being a tooling engineer, you are asked to re-design the depth of the mold so that there is no need for clamping force in casting this part. Please be aware that you do not have the flexibility to modify either the height or the width of the mold. What should be the minimum new depth?
(a) 7”, (b) 8”, (c) 9”, (d) 10”, (e) 11”. (4
points)
Your Answer: ____________
ME 3210
Woodruff School of Mechanical Engineering
Georgia Institute of Technology
Design, Materials, and Manufacture
Solutions for 1st Midterm Examination
1. In transverse stretching
Fall 2013
(1 Vf ) Vf
1 (1 Vf ) Vf
1
Vf 40%
Ec
Em
Ef
6.5
4
120
The answer is (c)
2. (a) (d)
3. For part A the is 180o and is 180o, thus ta is 0.8 sec; For part B the is 360o and
is 360o, thus tb is 1.6 sec. The answer is (e).
4. (b)
5. At 728oC, the alloy is in the two-phase field, with no cementite present.
C Co
0.77 0.40
49.5% . That is 4.95 kg
The weight % of is
C C 0.77 0.022
The weight of is 10-4.95=5.05 kg.
As 728oC is below the solidus, the alloy is completely solid.
So the answers are (c) and (d)
6. Call the required depth increment "a", cope weight increment clamping force before weight increment
36a
350
7.3 a 2" . Thus the minimum new depth is 6+2=8”
123
Answer is (b).
Woodruff School of Mechanical Engineering
Georgia Institute of Technology
Design, Materials, and Manufacture
1st Midterm Examination
Fall 2013
Note that multiple choices do NOT offer partial credits; check your calculations carefully.
1. Epoxy has density of 1.25 g/cm3 and elastic modulus of 4 GPa while Kevlar–49 has density of
1.5 g/cm3 and elastic modulus of 120 GPa. If a kelvar-49-reinforced epoxy composite is to have a transverse elastic modulus of 6.5 GPa, what should be its fiber volume fraction? (a) 65%, (b)
50%, (c) 40%, (d) 25%, (e) 10%. (3 points)
Your Answer: ___________
2. Which of the following regarding SPC is/are INCORRECT? (a) If the measuring resolution is
15% of the specified tolerance, the measurement …show more content…
is considered capable; (b) If the average of standard deviations of manufactured parts is 15% of the specified tolerance, the process would be considered capable; (c) If a manufacturing process has a process capability index of 110%, it would be considered capable; (d) If a manufacturing process has a process capability index of 65%, it would be considered incapable; (e) There is no way a manufacturing process is in control but is not capable. (4 points)
Your Answer: ____________
3. Parts A and B (in the left figure below) starting positions are random thus some
Which of the following is correct regarding for part B (tb) ? (a) 1.7 tb t a 1.3 tb ,
(e) (0.7)t b t a 0.3 t b . (3 points)
are to be inserted into the 3-pined base, while their hand orientation effort is needed before insertion. the orientation time for part A insertion (ta) and that
(b) 1.3 tb t a tb , (c) t a tb , (d) tb t a 0.7 tb ,
Your Answer: ____________
insertion
part B
Orientation time (s)
part A
3-pined
base
Manipulation by tweezers
Manipulation by hand
3
o
=360
2
1
o
180
o
360
o
180
o
0
0
0
100
200
(degree)
300
4. Name the process in the figure (a) centrifugal casting, (b) melt spinning, (c) crucible casting,
(d) rotational casting, (e) injection molding.
(3 points)
Your Answer: ____________ Gas
Crucible
Induction coil (for heating)
Melt
Strip (final product)
Copper disk
5. As a 10-kg of AISI1040 steel (plain carbon steel with 0.4% carbon) is cooled to 728oC, which statement is/are INCORRECT: (a) There is 5.05-kg austenite (); (b) There is 4.95-kg ferrite
(); (c) There is a 1.25-kg cementite (Fe3C); (d) The alloy is in a three-phase field of
Fe3C; (e) The alloy is 100% solid. (3 points)
Your Answer: ____________
6. An ellipsoid with major axes of 2", 3" and 4" is to be die cast in a graphite mold. The mold has a specific weight of 350 lbf/ft3 and outer dimensions of 6" by 6" by 6" as shown in the figure.
Note that the parting line of the mold lies on the plane of maximum cross-section of the casting.
In this case a clamping force of 7.3 lbf is needed to keep the mold haves from separation.
Being a tooling engineer, you are asked to re-design the depth of the mold so that there is no need for clamping force in casting this part. Please be aware that you do not have the flexibility to modify either the height or the width of the mold. What should be the minimum new depth?
(a) 7”, (b) 8”, (c) 9”, (d) 10”, (e) 11”. (4
points)
Your Answer: ____________
ME 3210
Woodruff School of Mechanical Engineering
Georgia Institute of Technology
Design, Materials, and Manufacture
Solutions for 1st Midterm Examination
1. In transverse stretching
Fall 2013
(1 Vf ) Vf
1 (1 Vf ) Vf
1
Vf 40%
Ec
Em
Ef
6.5
4
120
The answer is (c)
2. (a) (d)
3. For part A the is 180o and is 180o, thus ta is 0.8 sec; For part B the is 360o and
is 360o, thus tb is 1.6 sec. The answer is (e).
4. (b)
5. At 728oC, the alloy is in the two-phase field, with no cementite present.
C Co
0.77 0.40
49.5% . That is 4.95 kg
The weight % of is
C C 0.77 0.022
The weight of is 10-4.95=5.05 kg.
As 728oC is below the solidus, the alloy is completely solid.
So the answers are (c) and (d)
6. Call the required depth increment "a", cope weight increment clamping force before weight increment
36a
350
7.3 a 2" . Thus the minimum new depth is 6+2=8”
123
Answer is (b).