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Homework Help: Modulus of Elasticity with shear Corrected

  1. May 19, 2013 #1
    I appreciate your help with this problem from a Three point Bending Test in Wood samples

    1. The problem statement, all variables and given/known data

    Force: 2400 N
    Deflection: 4.3 mm
    Span: 343 mm
    Length: 392 mm
    b: 24.01 mm
    d: 24.25
    MOE: 16445.15 MPa

    How can I calculate the Modulus of Elasticity with shear corrected?

    2. Relevant equations

    I have this equation
    First I got the MOE=(Force*Span^3)/4*Deflection*b*d^3)
    then I should be able to calculate E but I don´t know how to get E/G

    3. The attempt at a solution
    The result must be 18417.95 KPa
  2. jcsd
  3. May 19, 2013 #2


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    Gold Member

    I assume you must estimate the E/G ratio for the particular species of wood. If your math is correct and the solution is correct (why so many significant figures??), looks like G = .05E, but I can't help much more . Might suggest search on G and E values for different species .
  4. May 22, 2013 #3
    I agree Jay's point. If deflection is 4.3 mm, then how many significant figures are reasonable for the solution? When you have worked out the answer to your question, try putting in 4.2 mm and 4.4 mm (which the deflection is NOT) and then conclude the so called accuracy of your answer....
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