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How to obtain Allowable Shear Stress

  1. Jun 5, 2009 #1
  2. jcsd
  3. Jun 5, 2009 #2
  4. Jun 5, 2009 #3


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    If not specified directly by your materials reference, a general rule of thumb is that the theoretical ratio between shear and tensile stress for a homogeneous, isotropic material is 0.577.
  5. Jun 5, 2009 #4


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    you are looking in terms of yield strength, the max shear stress theory and max distortion energy theory help.

    Max shear stress: Ssy=.5Sy
    Distortion-Energy theory: Ssy=.577Sy
  6. Jun 7, 2009 #5
    Thanks everyone.
    I get the answers 0.5X, right ^_^.

    Btw, I wonder what's the effect of Heat Treament on SAE-4340/ any steel. for example Quenching.

    What's the multiply factor on Yield and ultimate strength?
  7. Jun 7, 2009 #6


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    If you look in Machinery's Handbook, there is a nice section relating steel hardness to a relatively accurate form of estimating tensile properties. When you heat treat something, usually a Rockwell or some other hardness is mentioned as a requirement.

    In my latest copy (26th edition) it starts on page 473-474.

    My company did some internal testing quite some time ago with a lot of different alloys and found a relatively good relationship between the two parameters. The Machinery's section is pretty good.
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