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MSE 200
Test 2
ID number:
Answer all the questions below showing your detailed procedure of calculations.
Use the equations given at the end.
Q1. From the following stressstrain diagrams identify or determine the numerical values of the
following and provide the units for each quantity. ( 20 points)
1.
The engineering stressstrain curve and the true stresstrue strain curve.
2.
Yield strength, close to 20 Ksi at 0.2% strain
3.
Ultimate Tensile Strength, close to 25 Ksi
4.
Fracture strength, close to 35 Ksi on True stresstrue strain graph
5.
Total plastic strain, 0.45
6.
Engineering and true strain at necking, engng strain=0.25, true strain is ln(1.25)
7.
Engineering and true stress at necking, UTS= 25 Ksi, True stress= 25(1+0.25)
8.
Show the toughness of the material in the graph (not a value). Area under the graph.
1
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o
C,
show or determine numerically the following. Samples A and B are made of same material.
(points: 20)
1. Three stages of creep in sample A: loagrthmic, steady state and rapid creep
2. Steady state creep strain rate in sample A and sample B.
Sample A=0.001(0.00150.008)/(112) hour
1
Sample B=0.001(0.0220.008)/(92)
hour
1
3. Determine if sample A is subjected to creep at 600 or at 800
o
C: 600oC
4. Determine the activation energy for creep in the material.Use result from question 2 and
calculate
ln(strain rate ratio between T2 and T1)=(Q/k)[1/T21/T1). Knowing the strain rate ratio and
temperatures, calculate Q. Remember Q is not negative
5. Total creep rupture life at 600 and 800
o
C. 14000 hr and 11000 hr approximately.
2
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 Spring '08
 wholedepartment

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