Homework__1_Solutions

Fundamentals of Modern Manufacturing: Materials, Processes, and Systems

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Homework #1: 10 problems @ 10 points each = 100 total available points Due on September 1st, 2009 at 5 PM through the course web site Problems: 3.1, 3.2, 3.3, 3.4, 3.7, 3.8, 3.20, 3.24, 3.30, 3.31 3.1 A tensile test uses a test specimen that has a gage length of 50 mm and an area = 200 mm 2 . During the test the specimen yields under a load of 98,000 N. The corresponding gage length = 50.23 mm. This is the 0.2 percent yield point. The maximum load = 168,000 N is reached at a gage length = 64.2 mm. Determine (a) yield strength, (b) modulus of elasticity, and (c) tensile strength. Solution : (a) Y = 98,000/200 = 490 MPa. (b) σ = E e Subtracting the 0.2% offset, e = (50.23 - 50.0)/50.0 - 0.002 = 0.0026 E = σ/ e = 490/0.0026 = 188.5 x 10 3 MPa. (c) TS = 168,000/200 = 840 MPa. 3.2 In Problem 3.1, fracture occurs at a gage length of 67.3 mm. (a) Determine the percent elongation. (b) If the specimen necked to an area = 92 mm 2 , determine the percent reduction in area. Solution : (a) EL = (67.3 - 50)/50 = 17.3/50 = 0.346 = 34.6% (b) AR = (200 - 92)/200 = 0.54 = 54% 3.3 A test specimen in a tensile test has a gage length of 2.0 in and an area = 0.5 in 2 . During the test the specimen yields under a load of 32,000 lb. The corresponding gage length = 2.0083 in. This is the 0.2 percent yield point. The maximum load = 60,000 lb is reached at a gage
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Homework__1_Solutions - Homework#1 10 problems 10 points...

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