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Homework Help: Loaded Beams

  1. Jan 11, 2015 #1
    1. The problem statement, all variables and given/known data
    I need to plot a graph showing the deflection of the beam across its length giving a value of x at every 1m.
    The youngs modulus for the beam is 210 GNm^-2 and the moment of inertia is 54 X 10^-7 m^4

    2. Relevant equations
    Really unsure where to start on this one.

    I have found the equation M/IE= (d^2 y)/(dx^2) but I am unsure where to go from here

    3. The attempt at a solution

    Attached Files:

    • Beam.pdf
      File size:
      90.3 KB
  2. jcsd
  3. Jan 11, 2015 #2
  4. Jan 11, 2015 #3


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    Do you know how to calculate M for the beam with the given loading?
  5. Jan 11, 2015 #4
    I have calculated the bending moments at 1m intervals but I am not sure about calculating the internal moment?
  6. Jan 11, 2015 #5


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    It's not clear what you mean by 'internal moment'. The M which determines the deflection of the beam is the bending moment.
  7. Jan 11, 2015 #6
    In that case, to answer your question, yes i know how to calculate the bending moment(s) of the beam.
  8. Jan 11, 2015 #7
    SteamKing, can you please advise where I need to progress to from this?
  9. Jan 11, 2015 #8


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    You are asked to plot a graph. Does mean you are expected to do this numerically, rather than by solving a differential equation? I'll assume so.

    Starting at the point of support (x=0), you have zero deflection and zero gradient.
    You can use the equations you have to find the bending moment there, and hence find (d^2 y)/(dx^2).
    If you now step out a distance dx along the beam, what would you estimate y and dy/dx to be there?
  10. Jan 13, 2015 #9
    I have now found the solution. Thanks for the help.
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