Padeye - Simulation Experiment.

Discussion in 'Boat Design' started by Niru, May 5, 2014.

  1. Niru
    Joined: Jul 2010
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    Niru Mr.

    Good PM Pips.

    Doing some experiment with a simulation software.

    Padeye design with "supposed" S.W.L. 2 m tonnes. see attached pic3

    From analysis after putting 9810 Newtons Force (1 tons load/weight) on the lower surface of the pinhole. it went on a deformation.

    Its supposed to be a simple experiment went nowhere...Anyone here familiar with this kind of work?

    FEA Software Input :
    Element Type was brick
    Material was ASTM A36

    Many Thanks!
     

    Attached Files:

  2. NavalSArtichoke
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    NavalSArtichoke Senior Member

    Well, what kind of stress did the model give under load? Were you operating under the assumption that the padeye wouldn't deform when loaded?

    Your post isn't terribly clear. Remember, this forum isn't like Twitter: you can use more than 140 characters to ask a question.
     
  3. johnhazel
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    johnhazel Senior Member

    I did my masters thesis and published on FEA of Atomic Force Microscope cantilevers.
    http://tribology.asmedigitalcollection.asme.org/article.aspx?articleid=1465828

    Ok it looks like you have set the fixed points in the simulation as the top surface of the padeye. The color scale in both results is in units of mm deformation. Your grid is coarse. (circle represented by 12 straight lines) And the load seems to be specified on the bottom facet of the hole. Flipping between the two results (one with exaggerated deflection) shows a reasonable result.

    So what is your question?
     
  4. Niru
    Joined: Jul 2010
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    Niru Mr.

    good am.

    Sir's

    quite true - i did put a fixed constraint on the bottom part (straight part) of the padeye, assuming it was welded and on the lower facet of the pinhole for the load/force.


    @ NavalSArtichoke - yes i was assumming the padeye will not deform since it was designed to be able to lift a 2 tons weight max limit. static stress.

    @johnhazel - was wondering why did it deform. are all simulations perform did way.
    i thought it supposed to show either the design material/object can withstand such stress or not. even if i lower the load value still presents a deformation. can you clear my mind. just wandering.

    Many Thanks Sirs.
     
  5. johnhazel
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    johnhazel Senior Member

    All objects deform under any load. The deformation is tiny when the material is stiff and the load is small.
     
  6. Niru
    Joined: Jul 2010
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    Niru Mr.

    so whats the point of exagerating such defromation like in a simulation.

    Many Thanks on your comments!:cool:
     
  7. daiquiri
    Joined: May 2004
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    daiquiri Engineering and Design

    Niru, this is a serious advice - you need to study. And you need to study a lots, right from the basics. Go run to get a book about mechanics of materials, a very basic one. Only after you have read (and understood) it all, you can get back to your PC and to the FEM software you are using.
     
    1 person likes this.
  8. NavalSArtichoke
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    NavalSArtichoke Senior Member

    When plotting the deformed shape, the amount of deformation is magnified so that its magnitude becomes noticeable to anyone reviewing the plot. We also assign colors to indicate various levels of stress or temperature so that the regions where peak values of these properties occur are instantly apparent, without wading through a lot of numerical data.

    Only perfectly rigid bodies exhibit no deformation under load. That your padeye model exhibits deformation when loaded below the SWL does not necessarily mean it has failed. As long as the deformation is below a certain limit, the padeye is OK.
     

  9. Niru
    Joined: Jul 2010
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    Niru Mr.

    @ daiquiri - Copy that !

    @ NavalSArtichoke -

    "That your padeye model exhibits deformation when loaded below the SWL does not necessarily mean it has failed. As long as the deformation is below a certain limit, the padeye is OK."

    Thats Educational !
     
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