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Thread: Is x=0 the same as "at the support" in the Cantilever Beam Calculator Formula?

  1. #1
    Associate Engineer
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    Nov 2015
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    Is x=0 the same as "at the support" in the Cantilever Beam Calculator Formula?

    I am trying to determine the maximum stress in a Cantiever Beam.

    I think that this would occur at the support if the cross section of the cantilever beam is the same (constant) along its entire length (no knee at the support).
    I have tried using the Cantilever Beam Calculator found at http://www.engineersedge.com/beam_be...m_bending8.htm but there appears to be a discrepency in the calculator results.

    When the calculator is opened, default example design variables and calculated results are automatically loaded.
    When I change and set Disance (x)=0.00 and recalculate the results, I find that the stress at specfic point(s) is not the same a the calculated stress at the support.

    I think that it should be identical.

    For example, when
    W=1200
    l = 80.000
    x=40.000
    and using the the calculated output Z=102.889
    and the supplied formula
    i.e. stress = W/(2Zl)times(l-x)squared
    then stress = 116.63

    When x=0 then the stress is now calculated to = 466.52

    I conclude that the stress at the support should then be = Wl/2Z = 1200 (80.000)/2(102.889) = 466.522
    (This is not the displayed 5,000.0000)

    I can not offer a correction other than to suggest one check to confirm that the formula actually used in the calculator for stress a support is Wl/2Z as stated a then to determine why the result displayed is 5,400.0000 instead o 466.52 as when x=0.

  2. #2
    Administrator Kelly Bramble's Avatar
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    The maximum stress is given by the second equation (Stress at the support).

    "X" is used to determine stress at a specific point, where X could equal (0) zero.
    Tell me and I forget. Teach me and I remember. Involve me and I learn.

  3. #3
    Associate Engineer
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    I understand and agree that the maximum stress occurrs at the support.
    Where the support is at x=0.00 the calculator; however, still gives a result for maximum stress at the support (s) = 5,4000.0000 when it should be 466.5227 based on the formula said to be used in the calculator. This creates a discrepency. Is there an error in the calculato?

  4. #4
    Administrator Kelly Bramble's Avatar
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    Quote Originally Posted by Dug View Post
    I understand and agree that the maximum stress occurrs at the support.
    Where the support is at x=0.00 the calculator; however, still gives a result for maximum stress at the support (s) = 5,4000.0000 when it should be 466.5227 based on the formula said to be used in the calculator. This creates a discrepency. Is there an error in the calculato?
    Yes, you're right.. The calculator has been fixed and should show the correct answer.
    Tell me and I forget. Teach me and I remember. Involve me and I learn.

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