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Elastic modulus or Young's modulus

  1. Apr 12, 2012 #1
    I have a question

    Elastic modulus in Tensile test
    E = L*F / A*△L

    Elastic modulus in bending test
    E = F*L^3 / 4*w*t^3*D

    I think Elastic modulus is changed by size of specimen.

    I don't know why Elastic modulus is inherent propertie of metal??
  2. jcsd
  3. Apr 14, 2012 #2
    Elastic modulus is actually the elastic strain borne the atomic bonds. Since bonds in metals (metallic bonds) are isotropic (uniform) therefore elastic modulus remains the same regardless of the size of the object. Properties beyond the elastic limit however are transitive depending on different factors like grain size, microstructure constituents etc.
  4. Apr 15, 2012 #3
    If you were to actually do a tension test for a particular material that obeys Hooke's Law, and then plug in the ΔL measured, experimentally, into your first formula -- you would find that "E" is constant. In other words, "E" is independent of your applied force, F, as well as the dimensions of your specimen: L and A. "E" can therefore be said to be a property of material only (not geometry!).

    Similarly, if you were to do a three point bend test for that same material, and then plug in the deflection (D) measured, experimentally, into your second formula -- you would find that "E" is the same as before. "E" is again independent of the applied force, F, as well as the dimensions of your beam specimen: L, w, and t.


    What MalliCk said.

    Hope that helps..
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