Reference no: EM13314994
Your friend suggests that you can save a lot of weight by replacing steel with aluminum in beam structures. As a civil engineer you look up in your strength of materials book and find out that the deflection, for a square beam of width, t, and length, L, when subjected to a tensile force, F, is given by:??=FL/(Et2), where E is Young's modulus. Assume that the length of the beam and the force is the same regardless of the material chosen and that the allowed deflection, also a constant, is what determines the amount of mass needed.
a) Give a simple equation that shows mass in terms of L, F, and specific stiffness.
b) Assuming that the savings in mass is equal to the ratio of the specific stiffnesses, how much mass would be saved (i.e., what % reduction in mass) if you substituted an aluminum alloy for steel?
c) If polystyrene (PS) has an average number molecular weight of 6,000,000 g/mole, what is the average degree of polymerization for this polymer?
d) Why do even stiff polymeric materials, like PS, deform so easily compared to metals?
e) If aluminum beams had been used instead of steel in the World Trade Center towers, would the loss of life have been different? Why?
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Would the loss of life have been different and why
: As a civil engineer you look up in your strength of materials book and find out that the deflection, for a square beam of width, t, and length, L, when subjected to a tensile force, F, is given by: h=FL/(Et2), where E is Young's modulus.
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