t2sum032 - Home Introduction Policies Resources...

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Home Introduction Policies Resources Requirements & Grading Syllabus Assignments Handouts Discussion Web Links Distance Learners Contact MSE 200 Test 2
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KIC= σ f( π c) ½ ,e'= e o'exp(-Q/kT), e=ln(l/lo), e=(l-lo)/lo, σ =F/Ao, σ =F/A All questions carry 2 points. Q1. A sample of cross sectional area 0.1 sq. inches has been subjected to a tensile test. The load versus elongation curve is shown below. Answer the following questions. 1.The region of design of structures is a. OA b. AB c. BC (a ) 2. The yield strength is close to a. 80 Ksi b. 70 Ksi c. 60 Ksi ( b) 3. Necking starts around point a. A b. B c. C ( b) 4. True strain at necking is close to a. 0.104 b.0.0677 c. 0.0488 (b ) 5. Can we determine the true fracture strength from the above graph a. yes b. no (b ) 6. The fracture strength is a. greater than 85 Ksi b. less than 80 Ksi c. close to 75 Ksi (a ) 7. Total plastic strain in the sample is a. greater than 0.11 b. close to 0.045 c. close to 0.07 (b ) 8. The magnitude of the power hardening exponent of the sample is a. 0.104 b.0.0677 c. 0.0488 ( b)
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Q2. A high strength steel of grain size 16 mm has a yield point of 1460 MPa and a crack of 0.0014 meters lead to failure at yield. When the grain size is reduced to 4 mm, the yield strength of the steel increased and the crack size for failure at yield strength is found to reduce to 0.0018 meters. The yield strength of very large size steel is 60 Mpa. Answer the following questions. 1. The fracture toughness of steel in Mpa(m) 1/2 with 16 mm grain size is a. 40 b. 98 c. 196 (b ) 2. The yield strength of the steel in Mpa when the grain size is 4 mm is a. 2860 b.2000 c.1000 ( a) 3. The toughness of steel in Mpa(m) 1/2 with grain size 4 mm is a. 98 b. 215 c. 196 (b ) 4. A titanium alloy with grain size of 4 mm exhibited a yield strength of 2392 Mpa and a crack length of 0.0025 meters lead to failure at yield. The fracture toughness of the titanium alloy is a. 211 b. 212 c. 196 (b ) 5. For aircraft structures, would you use steel with higher strength in
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t2sum032 - Home Introduction Policies Resources...

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