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Homework Help: Finding maximum allowable alternating stress using goodmans relation

  1. Feb 6, 2013 #1
    1. The problem statement, all variables and given/known data

    (b) A steel alloy has an ultimate tensile strength of 820MN/m2 and a fatigue endurance limit of 390MN/m2. The steel is used in a fatigue application in which the alternating stress is 0.3 times the mean stress. Using the Goodman method with a factor of safety of 1.5 applied determine the maximum allowable alternating stress that will allow safe operation

    2. Relevant equations
    σa = σfat x (σm/σts)
    Where σa is the alternating stress, σm is the mean stress, σfat is the fatigue endurance limit and σts is the ultimate tensile stress.

    3. The attempt at a solution
    So far I have substituted σa for 0.3 x σm and tried to rearrange this formula, I have however run into problems and am doubting this is the correct method.
  2. jcsd
  3. Feb 8, 2013 #2
    Re: Finding maximum allowable alternating stress using goodmans relati

    Any ideas? The entire assignment is due in on monday and this is all i'm having problems with.
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