TEST2_ENSC3313_SP2007_KEY

# TEST2_ENSC3313_SP2007_KEY - ENSC 3313 Spring 2007 TEST 2...

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1 ENSC 3313, Spring 2007 TEST 2 - KEY Name_________________________ Answer all 10 questions, show all work, 2points each 1. The figure below is for a brass rod, 12.5 mm diameter and 50 mm gauge length. The Poisson’s ratio is 0.35. Please determine (a) the elastic modulus, (b) tensile strength, (c) yield strength (0.2% offset), and (d) the elongation at fracture. Please give your answers in metric units . a. ε σ = E in the elastic region GPa 85 002 . 0 MPa 170 = = b. TS = highest stress reached on the stress/strain curve, ~ 450 MPa. c. YS is taken at 0.2% offset YS = 250 MPa d. The strain at fracture is ~ 0.37. The gauge length is 50 mm. Hence, the elongation is ~ (0.37)(50) ~ 18.5 mm. 2. Calculate the resolved shear stress ( τ r ) for the (110)[ 11 1 ] slip system of α -ferrite if a 30ksi stress is applied in the [210] direction. Recall the cosine of the angle between two vectors is: 2 1 2 1 v v v v cos = θ The resolved shear stress formula is: φ λ σ τ cos cos = r 15 1 cos ; 10 3 cos = = Hence, ksi r 35 . 7 150 3 = = x y z (110) [111] [210]

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2 3. In class I showed this broken liberty ship. Explain what course theme is being illustrated and state the material and crystal structure prone to this type of failure. The theme is ductile-to-brittle transition.
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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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TEST2_ENSC3313_SP2007_KEY - ENSC 3313 Spring 2007 TEST 2...

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