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Unformatted text preview: 2 e 2 e 2 e Total Operating Cost Total Operating Cost C = C 1 + C 2 = C m AL ρ + C e I 2 [ ρ e L/A]t Differentiating cost with respect to area and setting the derivative equal to zero gives the optimum value for cross sectional area for the minimization of total operating cost: A opt = [C e ρ e I 2 t/(C m ρ )] 1/2 Substituting A opt back into the total cost equation gives the objective function : e 2 1/2 m e 1/2 “Cost is minimized by selecting the material with the greatest value of”: M 1 = 1/[C m ρ e ρ ] “Strength is important when a busbar of large span is unsupported or is exposed to other loads . Then we require a minimum value for the elastic limit.” graphite • For cost and strength, bronzes are best • Without strength, would have selected graphite...
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 Spring '11
 Mecholsky
 Heat, Strain, temperature rise

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