Exterior Fiber on Shaft

Discussion in 'Boat Design' started by nero, Apr 28, 2009.

  1. nero
    Joined: Aug 2003
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    nero Senior Member

    When laying up a tapered shaft, do the shorter lengths of fiber go next to the center of the shaft with the full length fibers near the outside surface? Or do they go near the outside surface with the full length fibers running near the center?

    Thanks if anyone can give me a quick response.

    Regards
     
  2. Ad Hoc
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    Ad Hoc Naval Architect

    whatever material is in the centre of the shaft does nothing for torsion!
     
  3. nero
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    nero Senior Member

    Yes that is correct.

    Perhaps I need to be more precise. The core is corecell. The top of the shaft has a larger dimeter than the bottom of the shaft due to thicker laminates in this area. This means that not all of the 0 degree fibers will be full length. There will be several series of layers that step back toward the fat end.

    My question is: Do I start with the short fibers and build out the shaft at the top and then progressively go to the full length fibers? Or is it the inverse layup?
     
  4. Ad Hoc
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    Ad Hoc Naval Architect

    Hmmm....terminology again.
    Bottom of shaft??..you mean one end of the shaft, yes?...since there is no "bottom" of a shaft!

    Well, firstly what does the design dwg say, do you have one?..if not, what is the design for, has this been calculated by you or another?

    The short fibres, i am assuming in this case, are for merely tapering the shaft or 'filling' out. If this is the case, then the shorter fibres are best underneath the longer fibres. Since the long full length fibres take the strain along the entire length, and these being the outermost fibres.

    So, think of the shorter ones as being just "gap fillers" to allow you to construct a tapered shaft. Because without the need to taper, there is no 'gap filling' hence the shaft is made entirely of long fibres. If i understand you correctly.
     
  5. Landlubber
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    Landlubber Senior Member

    I understand your problem, the parallel fibres are on the outside, the tapered ones on the inside.
     

  6. nero
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    nero Senior Member

    Thanks Landlubber and Ad Hoc.

    I was thinking that the full length fibers shoud be on the outside.

    However, I had this idea if the shorter fibers were on the outside, the effect would be somewhat like a leaf spring on a car.

    Will stick them near the center as y'all advised.

    Thanks again
     
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