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Question 8.

The material for a rod of cross-sectional area 2.70 in2 and length 75.0 inches must be selected such that under an axial load of 120,000.0 lb, it will not yield permanently and the elongation in the bar will remain below 0.105 inches.

(a) Make a list of least three different metals that would satisfy these conditions.

(b) Choose a material from the above list if cost is an issue.

(c) Choose the material from the above list if corrosion is an issue. Question 7.

Q9. Compare the yield strength of a copper specimen with an average grain diameter of 0.8 μm with another copper specimen with an average grain diameter of 80 nm assuming the Hall-Petch equation applies. Make an observation on the effect of grain size on the yield strength of the material.

Assume that σo = 25 MPa for this material.