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Yielding stress

  1. Dec 9, 2009 #1
    as depicted in the diagram below
    the stress strain for an alloy with an average nucleus size of 100 micron
    1)the modulus of elasticity for the alloy
    2) the yielding stress

    for 1) i assume that the red line is meant to be at 0.0005 therefore


    for 2) i dont know what i can do, all that i do know is that the slant of the line from ε=0.002 to the point of σy is equal to 200Gpa (from the E i found before), but how can i use this to find the stress, i do not know the strain for σy, since i was given the nuclesu size i think i must somehow use that, but how??
  2. jcsd
  3. Dec 9, 2009 #2


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    Ignore the 100 micron nucleus info. The sample yields where there is a deviation from a linear stress/strain relationship, right?
  4. Dec 9, 2009 #3
    but how can i use that information, when you say a deviation from stress strain relationship, do you mean a deviation from the young modulus? i dont think that thats true, is there not a small portion where the line is not linear but before yielding?
    even on the graph there is a portion between the linear section and the point marked as 2 with the green line
  5. Dec 9, 2009 #4
    i think i need to use the imaginary linear line that starts at 0.2% and rises to yielding stress at a slant equal to E
  6. Dec 10, 2009 #5


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  7. Dec 10, 2009 #6
    now i assume that the apropriate strain for the yielding stress is 0.003, is that correct?



    is this correct? according to the graph it cannot be
  8. Dec 10, 2009 #7


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    It's simpler than that. The convention is to use the stress where the 0.2% offset line meets the actual stress-strain curve.
  9. Dec 10, 2009 #8
    but i dont know the function of the actual curve, do you mean the linear section,


    dont think thats what you mean,

    how can i find the curve after the linear section?
  10. Dec 10, 2009 #9


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    You read it off by eye.
  11. Dec 10, 2009 #10
    is there no way to calculate it?
  12. Dec 12, 2009 #11
    Last edited by a moderator: May 4, 2017
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