replace stainless chainplate with carbon

Discussion in 'Materials' started by seandepagnier, Dec 14, 2020.

  1. seandepagnier
    Joined: Oct 2020
    Posts: 17
    Likes: 2, Points: 3
    Location: the sea

    seandepagnier Junior Member

    Rather than bonding carbon to the hull which is discussed in most places, is it possible to simply lay up carbon in the shape of the chainplate and put the bend in (while lay up) if needed then bolt the carbon on?

    Is this going to break? Most designs run the carbon around a pin, so would having a hole in the carbon be an issue? Should the carbon run around a pin but can it still be bolted on? Will this simply not work well to bolt carbon because normally the strength is the friction between chainplate and hull not the bolts so maybe it will be an issue. What about fatigue? Will carbon crack over time? Will the carbon eat through metal bolts because it's conductive? What type of bolts would be possible?

    Sorry for all the questions, but I can't find much info and I think it may make sense to do this or maybe I'm missing a few key issues.
     
  2. jehardiman
    Joined: Aug 2004
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    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Carbon fiber is very sensitive to the load direction, and bolting a fitting in tension is specifically a bi-axial loading case. While I'm not saying it can't be done, it will take a fair amount of analysis to answer all the design requirements for a bolted carbon chainplate. Better to select a material with good bi-axial properties from the beginning.
     
  3. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    I would NOT trust a drilled and bolted carbon plate.

    As Jehardiman noted;. Drilling would cut the fibers and weaken the plate.

    Carbon is conductive but epoxy isn't. Using a pin doesn't cut any fibers and puts am insulating layer of epoxy between the carbon and bolt.

    If the bolts can be isolated from the carbon, and are if sufficient size, and pattern:. Then bolt on may work
     

  4. seandepagnier
    Joined: Oct 2020
    Posts: 17
    Likes: 2, Points: 3
    Location: the sea

    seandepagnier Junior Member

    What about uni-directional carbon spread apart at delrin bushings where the bolts go through before layup? no drilling or cutting of fibers, and isolating the bolts from the carbon. I am thinking the bolt would be titanium or duplex stainless, however I cannot find a good source of 2205 fasteners.

    Then also considering how to attach lashings (for synthetic rig) what about wrapping the carbon around a 2 inch delrin round bar which has the holes drilled in it for lashings to go through? Or would it be advisable to use metal somewhere? Is it essential the chainplate is very near the deck so it cannot flex if made of carbon? Perhaps the fibers should go on both inside and outside of hull?

    I do not wish to bond the chainplate to the hull because it was not designed this way originally, and I would not get a chemical bond. The hull also is foam core and has wood where the chainplates attach.. it is much simpler to use bolts if this is at all viable.
     
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