Test2Sp02

# Test2Sp02 - .9 . ~ Answer alllO Questions. 2 Doints Name...

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.9 .. ~ ENSC 3313, Spring 2002 TEST 2 Name Answer alllO Questions. 2 Doints each. A M tensile test specimen, of gauge length 4 inches and width 1.0 inches, was cut from a sheet of thickness 0.25 inches. The load-elongation plot is as shown. Calculate a) the elastic modulus, b) yield strength, c) tensile strength, d) % elongation. Cross section area = 1.0 x 0.25 = 0.25 in2 Stress = Load/ Area Gauge length is 4"; strain = elongation/4 a) E = (1500/0.25)/(0.006)/4 = ~~ 106 psi b) YS ~ 2000/0.25- 8,000 psi (approx) c) TS 5800/0.25- 23,200 psi d) % Elongation (0.54/4)100 ~ 13.5% ~ 2. I showed this picture of the SS Jeremiah O'Brien on the overhead projector as part of a presentation on a theme of course relevance. Explain! The theme is the ductile to brittle transition in steel! This is the last seaworthy World War II Liberty ShiR! Steels go ~ at low temperatures. Several thousand were built. This was the first big usage of all welded construction. About 1,000 developed severe cracking problems because the steel did not have enough toughness at "cool" sea temperatures. The ductile to brittle transition temperature was too high. Being welded, instead of riveted, there were no discontinuities to stop a crack. Several of these ships split completely in two. You might recollect, too, that I told that this ship

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## This note was uploaded on 01/10/2012 for the course ENSC 3313 taught by Professor Staff during the Fall '11 term at Oklahoma State.

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Test2Sp02 - .9 . ~ Answer alllO Questions. 2 Doints Name...

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