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Homework Help: Calculate the Young's modulus

  1. Jan 11, 2015 #1
    Hey Guys, I am new to the forums but have seen you guys help alot with pointing people in the right direction.

    Here is my problem:
    A Cylinder with a Volume of 8000m3 has a pressure of 80MPa, Bulk Modulus of 74 MPa. I need to calculate the Young s modulus and determine the material type.

    So Far here is what i have:

    Using Bulk Modulus, Volumetric Strain can be found:
    Bulk Modulus K = Pressure / Volumetric Strain
    Volumetric Strain = Pressure / Bulk Modulus K = 80 x 106 Pa / 74 x 106 Pa = 1.081
    Volumetric Strain Can also be determined using this formula:
    Volumetric Strain = Change in Volume / Volume
    Then the Change in Volume can be found using the Volumetric Strain:
    Change in Volume = Volumetric Strain x Volume = 1.081 x 8000m3 = 8648m3

    My train of thought with calculating the youngs modulus is to use

    E = Stress (Volume x Pressure) / Volumetric strain
    So E = 592.05 GPa

    Or by Using K
    E = 3K(1-2v) --> 3x74MPa x (1-0.6) = 88.8MPa

    But neither answer looks right. Have i overlooked something here?

    Your input will be greatly appreciated.
  2. jcsd
  3. Jan 11, 2015 #2
    well. i think bulk modulus =direct stress/ vol strain .here pr stress
  4. Jan 11, 2015 #3
    Thanks for the reply Praveen. I have looked at going back and getting the area of the cylinder and working through stress and strain but im getting x10^6 numbers which is low for the elastic modulus.
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