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Homework Help: Calculating Ultimate Tensile Strength?

  1. Mar 9, 2014 #1
    1. The problem statement, all variables and given/known data

    A metal of cross-sectional area 3.22E-4 m2 is being tested in compression. At an engineering strain of 20%, the compression load of the sample is determined to be 25000lb. Calculate the true stress and true strain at that point. Assume sigma=A(epsilon)N where the strain hardening exponent N=0.35. Calculate the ultimate tensile strength assuming m=0.

    2. Relevant equations

    true stress = P/A
    true strain = ln(1+e) where e=deltaL/L
    m=d*ln(stress)/d*ln(strain rate)
    ultimate tensile strength = Pmax/Ao
    sigma = A(epsilon)^0.35

    3. The attempt at a solution

    So far I have calculated true strain epsilon to be 0.182 by substituting 0.2 into e. Then I calculated true stress to be P/A = (11205N)/(3.22E-4m2)=3.48E7 Pa. Now I don't know what do to calculate the ultimate tensile strength. I determined A=6.32E7 but now what?
  2. jcsd
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