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Homework Help: Deflection cantilever beam

  1. Oct 11, 2013 #1
    1. The problem statement, all variables and given/known data
    How do I find an expression for the deflection at midspan for a cantilever beam loaded with a uniformly distributed load?

    Illustration of beam: http://goo.gl/3SxeVZ [Broken]

    2. Relevant equations
    [itex]\delta = \frac{Qx^2}{24EI}(6L^2-4Lx+x^2)[/itex]

    3. The attempt at a solution
    Attempt at solution: http://goo.gl/umUBkU [Broken]

    My current answer is: [itex]\frac{49QL^4}{1280EI}[/itex], I think this is wrong. Putting [itex]x = \frac{L}{2}[/itex] in the elastic curve formula I get: [itex]\frac{17QL^4}{384EI}[/itex], I think this is the correct answer.
    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Oct 11, 2013 #2


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    You can always check your formula for the deflection by setting x = L and seeing if your result is the same as that from a beam table.
  4. Oct 13, 2013 #3


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    raymanmusic: qx = q, not qx = q*x/L. Try again.
  5. Oct 14, 2013 #4
    Yes, that was the mistake. I got the correct answer now: [itex]\frac{17QL^4}{384EI}[/itex]. Thank you nvn.
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