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Homework Help: Mechanics of Materials Bending Stres Problem

  1. Jul 10, 2005 #1
    Mechanics of Materials Bending Stress Problem


    I have a homework problem for mechanics of materials involving bending stress. Here is the exact wording:

    "Show that the maxiumum bending stress for a beam of rectangular cross-section is Omax = Mc/I [(2n + 1) / (3n)] if instead of Hooke's law, the stress-strain relationship is O^n = Ee, where n is a number dependent on the material."

    --NOTE: Omax is the maxiumum bending stress

    Essentially the diffence is not using Hooke's law: O = Ee (e is the strain). Using Hooke's law yields the flexure formula: Omax = Mc/I.

    So far I have got O^n = Omax^n * (y/c)
    but when I insert this into the equation dM = ydF or dM = yOdA I am uncertain how to obtain I (the moment of Inertia)

    Any help would be greatly appreciated.
    Last edited: Jul 10, 2005
  2. jcsd
  3. Jul 10, 2005 #2
    the moment of inertia is calculated by the eq. [1/12*b*h^3]
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