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Bulk and shear modulus

  1. Dec 4, 2014 #1
    1. The problem statement, all variables and given/known data
    A material which has a Young’s modulus of elasticity of 250 GN m–2 and
    a poisons ratio of 0.32, calculate:

    (a) the bulk modulus of the material

    (b) the shear modulus of the material.

    2. Relevant equations
    E=3(1−2ν)K

    3. The attempt at a solution


    a)

    E = 3(1−2ν)K

    K = E / 3(1-2*0.32)

    K = 250/(3(1-2*0.32)

    250 / K = 1.08

    bulk modulus, K = 231.48

    Are my working for A correct? I'm stuck with working out the shear modulus, please can anyone help?
     
  2. jcsd
  3. Dec 4, 2014 #2

    SteamKing

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    You are missing the units for the bulk modulus.

    It's not clear why you can't calculate the shear modulus. There's a nifty formula for that, similar to the one for calculating the bulk modulus.
     
  4. Dec 4, 2014 #3
    What's your equation for the shear modulus in terms of Young's modulus and poisson's ratio?
     
  5. Dec 4, 2014 #4
    G = E / (2(1-V))

    G = 250 / (2(1-0.32)

    G = 250/1.36

    Shear Modulus, G = 183.82
     
  6. Dec 4, 2014 #5

    SteamKing

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    Still going without units, I see.
     
  7. Dec 4, 2014 #6
    I guess the units would be Pascals, Pa?
     
  8. Apr 9, 2015 #7
    can anyone help me with this?
     
  9. Apr 9, 2015 #8
    You're still trying to figure out the units?

    Chet
     
  10. Apr 9, 2015 #9
    I believe the unit for bulk modulus will be pascals.

    I'm still trying to get the shear modulus.
     
  11. Apr 9, 2015 #10
    Did you not read you own post #4?

    The units in all these cases is GPa.
     
  12. Apr 9, 2015 #11
    I think the answer in post 4 is incorrect, the formula is not correct. I think it should be

    G = E / (2(1 + ѵ))

    G = 250/(2(1+0.32))

    G = 250/2.64

    G = 94.7

    Shear Modulus, G = 94.7 GPa
     
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