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Homework Help: Bending Beams

  1. Sep 2, 2008 #1
    1. Derive an expression for the vertical deflection v of the beam of figure Q1
    b) if E=200GPa and I= 750*10^-6 m^4, find the position and magnitude of the maximum upwards vertical deflection.
    http://photos-d.ak.facebook.com/photos-ak-snc1/v319/114/101/695150024/n695150024_1209371_3981.jpg [Broken]

    2. EId²v/dz²=equation of the beam
    dv/dz=0 at max deflection

    3. EId²v/dz²=20/6z³+100[z-3]²-20/6[z-8]³+Cz where C is calculated to be 525.83

    i was wondering wether this is correct, and if R at the clamped side of the beam is 20kN
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Sep 2, 2008 #2


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    this is the equation for the bending moment in the beam
    dv/dz = 0 at the fixed end
    I am not sure what you are doing here. You have to look at both the applied load deflection and the deflection from the applied couple. The moment from the applied load is 20x, and the moment from the couple is 200 for the first 3 feet, and zero therafter.
    The vertical reaction is 20, but there is also a couple at that end. If you are being asked to derive the deflection along the beam, and a particular max upward deflection, it's a bit of a tedious process using calculuis and boundary conditions.
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