Permissible Shear forces and bending moments harbour/ still water

Discussion in 'Class Societies' started by JoshTruman, Mar 17, 2019.

  1. JoshTruman
    Joined: Dec 2018
    Posts: 4
    Likes: 0, Points: 1
    Location: Lithuania

    JoshTruman New Member

    Good day friends,
    I'd like to ask you about - how to calculate permissible shear forces and bending moments in harbour condition and still water .
    I just want to calculate it manualy for existing model of the ship.
    It is easy to calculate shear forces and bending moments acting through the ships lenght but I do not know how to calculate/ derive permissible value for exact position i/e: x=50 [m] to plot curve of permissible shear/ bending curves for harbour and still water.
    I am kindly waiting for any advice/ suggestion or working example.
    Best Regards

    upload_2019-3-17_19-35-21.png
     
  2. Ad Hoc
    Joined: Oct 2008
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    Location: Japan

    Ad Hoc Naval Architect

    Josh

    Just follow the procedure shown and outlined in any good naval architecture text book.
    Work out the weight per unit length and lay over the buoyancy curve when in a static condition:
    upload_2019-3-18_8-31-9.png
    and then, obtain the positive and negative contributions along the length:
    upload_2019-3-18_8-32-4.png
    and then, apply a wave (buoyancy curve) onto the static vessel:
    upload_2019-3-18_8-33-15.png

    That's it.
     

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  3. TANSL
    Joined: Sep 2011
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    Location: Spain

    TANSL Senior Member

    The shear force at point X is equal to the weight at that point minus the buoyancy in it. The bending moment is the resultant of the moments of the forces located to the right of said point with respect to that same point. As "simple" as that.
     
  4. JoshTruman
    Joined: Dec 2018
    Posts: 4
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    Location: Lithuania

    JoshTruman New Member

    Many thanks for your reply- calculation of SF and BM is simple.
    I mentioned maximum safe range of shear force and bending moment in function of length of the ship. Permissible harbour/ Seagoing( sometimes called stillwater) limits.
    upload_2019-3-18_7-52-20.jpeg upload_2019-3-18_7-53-41.jpeg
    Best regards
     

  5. TANSL
    Joined: Sep 2011
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    Location: Spain

    TANSL Senior Member

    Consult what Classification Societies or any other regulatory body says about it.
     
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