Buckling of profile

Discussion in 'Sailboats' started by pulsar, Sep 15, 2007.

  1. pulsar
    Joined: Aug 2006
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    Location: Poland

    pulsar Mechanical engineer

    Hi,

    How to calculate buckling of beam (length L, circular section), which is fixed on 6 degree of freedom at bottom part (movement and rotation) and catched at the end. I have axial force and out of center force at the endas it is shown on picture. I have found examples with only axial forces for that moments, but it don't help me.
    I need some simple explanation. I mean with simple formula without integrals and differentials.

    Pulsar
     

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  2. Guillermo
    Joined: Mar 2005
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    Location: Pontevedra, Spain

    Guillermo Ingeniero Naval

  3. MikeJohns
    Joined: Aug 2004
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    Location: Australia

    MikeJohns Senior Member

    Unfortunately there is no easy solution. Eccentrically loaded columns require some complex mathematics and manual solutions would start with the Secant formula. As Guillermo has suggested the answer for an easy solution for you lies in software. I would recommend that you use "Cadre" from Guillermo's second link above. It comes with excellent tutorials and supports cable elements as well. Cross check any calculated second moment of area with some one else's calculations to ensure you are in the ball park.
     
  4. tspeer
    Joined: Feb 2002
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    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    Try Roark's Formulas for Stress and Strain. My copy is at the office, so i can't look it up for you at the moment.
     
  5. pulsar
    Joined: Aug 2006
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    Location: Poland

    pulsar Mechanical engineer

    oh... it's more optimistic news.

    Thanks in advance
    Pulsar
     
  6. PI Design
    Joined: Oct 2006
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    Location: England

    PI Design Senior Member

    Yeah, Roark has a table for eccentrically loaded columns. There is no single easy formula as it depends, amongst other things, on the cross sectional shape of the column.
     
  7. pulsar
    Joined: Aug 2006
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    Location: Poland

    pulsar Mechanical engineer

    I beg your pardon, but who is Roark and how to get those formulas?
     
  8. water addict
    Joined: Jun 2004
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    Location: maryland

    water addict Naval Architect

    Curious- why do you need this? Just happily computing away buckling equations for fun?
     
  9. pulsar
    Joined: Aug 2006
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    Location: Poland

    pulsar Mechanical engineer

    I'm during designig gangways for roro ships. Buckling calculation is for checking main beams which support passengers stairs.
    The main beam must be small as it's possible.

    That's why:)
     
  10. Guillermo
    Joined: Mar 2005
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    Location: Pontevedra, Spain

    Guillermo Ingeniero Naval

  11. MikeJohns
    Joined: Aug 2004
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    Location: Australia

    MikeJohns Senior Member


    And you haven't access to a FEA package :confused:
     

  12. pulsar
    Joined: Aug 2006
    Posts: 32
    Likes: 1, Points: 0, Legacy Rep: 30
    Location: Poland

    pulsar Mechanical engineer

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