t2sum03

# t2sum03 - Home Introduction Policies Resources Requirements...

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Home Introduction Policies Resources Requirements & Grading Syllabus Assignments Handouts Discussion Web Links Distance Learners Contact MSE 200 Test 2 Q1. A test bar of aluminum has a diameter of 0.505 inches. Upon

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applying a tensile load, the sample exhibited 0.002 plastic strain at 1700 lb and the maximum load during testing was 3100 lb; and breaking occurred at 2200 lb. The sample diameter at fracture was measured to be 0.169 inches. The power hardening exponent of this material is 0.45. Answer the following questions. 1. The yield strength of the material is a. 9493 psi b. 8487 psi c. 16975 psi ( b ) 2. The UTS of the material is a. 16975 psi b. 15477 psi c. 30954 ( b ) 3. The fracture strength of the sample is a. 11000 psi b. 98075 psi c. 138197 psi ( b ) 4. True strain at necking is a. 0.50 b. 0.45 c.0.1 ( b ) 5. Engineering strain at necking is a. 0.57 b. 0.65 c. 0.11 ( a ) 6. Draw below the stress-strain curve of the aluminum samples and show the different points that are calculated above and may be calculated for completing the graphs. Q2.A steel with a critical fracture toughness of 150MPa.m1/2 has a yield strength of 1200 Mpa. If fracture were to take place at the yield stress, answer the following questions. 1.Surface crack size at yielding leading to failure is a. 0.497 cm b. 0.994 cm c. 0.249 cm ( a ) 2.If the fracture toughness is increased to 300 Mpa.m 1/2, what is the stress value in MPa at which failure takes place for the same crack size.
a. 2400 b. 600 c. 1200 ( a ) 3. The size of the crack in the infinite medium that gives the same failure stress of 1200 Mpa is a. 0.497 cm b. 0.994 cm c. 0.249 cm ( b ) 4. If the yield strength is used as a measure to improve the fracture toughness from 150 MPa.m1/2 to 300 Mpa. m1/2 and if the yield strength for very large grain size is 200 Mpa, the grain size need to be decreased by a factor of a. 2.2 b. 4.8 c. 10 ( b ) Q3. In a laboratory creep experiment at 1000oC, a steady state creep rate of 1.5x10-6 sec-1 is observed in nickel. When the experiments are performed under the same stress at 800oC, the observed creep rate is 1.0x10-6sec-1. Predict the creep rate at a service temperature of

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## t2sum03 - Home Introduction Policies Resources Requirements...

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