Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Engineering Stress increases after yield stress?

  1. Feb 14, 2016 #1
    I need to know why the Engineering stress increases after reaching the yield stress point, and continues to increase until reaching the UTS. Am I correct when I remember that there is strain hardening that occurs along the region from Yield stress to the Ultimate tensile stress? Engineering stress equals Force divided by Original cross-sectional area: σ=F/Ao
    My first thoughts were that obviously as you increase the force, the stress will increase (from a purely mathematical outlook, this is apparent since stress increases proportionally to force). How could this be explained in better engineering terms?
  2. jcsd
  3. Feb 15, 2016 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Does it need a better explanation than the increase in applied force leads to an increase in stress, regardless of how that stress is calculated?
  4. Feb 15, 2016 #3
    The question is: "From the onset of plastic deformation up to the UTS, the engineering stress increases. Discuss in Engineering terms why."
    This is for a lab report in which we performed a tensile test on three materials, steel, copper, and aluminum
  5. Feb 16, 2016 #4


    User Avatar
    Science Advisor

  6. Feb 16, 2016 #5
    Yes, thank you both for your insight. I asked the instructor also, and the answer he was looking for was regarding the cold work/strain hardening that occurs as a result of dislocations from the plastic deformation.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook