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sol-as2-c10(2) - SOLUTION TO HOMEWORK NO 2 Summer 2010 1(8...

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SOLUTION TO HOMEWORK NO. 2 Summer 2010 1. (8 pts each. -2 pts for not showing units or wrong units. -4 pts for not showing work.) 0 2 4 6 8 10 12 14 16 18 20 STRAIN (10 -3 ) 50 40 30 20 10 0 STRESS (KSI) JAEL y 39 38 37 (A) E = 30 ksi / 4 X 10 -3 = 7.5 X 10 3 ksi (B) JAEL = 30 ksi (C) Yield strength at 0.1% offset = 37 ksi (D) Modulus of resilience = 30 ksi (4 X 10 -3 ) / 2 = 60 X 10 -3 ksi = 60 psi (E) Using the unit of psi, area under the stress-strain plot up to failure can be calculated as: Modulus of toughness = 60 + (30 + 37)/2 X 2 + (37 + 38)/2 X 2 + (38 + 39)/2 X 10 = 587 psi 2. (A) From the S-N diagram, the cyclic stress for 100,000 cycles is 220 MPa. (5 pts.) (a) Soderberg: (b) Goodman: (300 – X) / 140 = 300 / 220 (360 – X ) / 140 = 360 / 220 (300 – X ) = 190.9 360 – X = 229 X = 109.1 MPa (5pts.) X = 131 MPa (5pts.) (5 pts. for showing the correct plots.) Cyclic Stress (MPa) 220 300 360 Steady Stress (MPa) Goodman Soderberg 140 X X = additional steady stress on top of the cyclic stress to cause failure.
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