Carbon/Kevlar shaft layup questions

Discussion in 'Fiberglass and Composite Boat Building' started by nickireson, Jan 26, 2011.

  1. nickireson
    Joined: Jan 2011
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    nickireson Junior Member

    Hey everyone,

    Ok, so I am planning on making a few composite handlepoles for stand-up jetskis. I have a few questions though.

    The handlepole will be similar to this:
    [​IMG]

    The Black parts will be aluminum, I intend on having some parts machined to handle that part. The composite shafts will fit into the aluminum mounts which in the above image, are represented by the silver aluminum.

    So....
    Would it be best to use a carbon/kevlar 50/50 blend, or just carbon?
    Also, if I use the medium strength sleeve from Soller Composites will 3 layers be adequate? The poles will probably take a lot of abuse, and I want to ensure that they will not fail. Some riders will be in heavy surf, doing backflips, submarines, etc...
    Next, there is a product they sell that is a heat shrink tubing that you use after the wet lamination to get a tight layup and squeeze out excess resin.
    Is this process even remotely comparable to a vacuum bagging process or not as beneficial as far as added structural integrity?
    Many thanks in advance. Also if you have any thoughts or comments about things I didnt mention yet, all input will be welcomed.
     
  2. War Whoop
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    War Whoop Senior Member

    Carbon prepreg ,those are small pieces.
     
  3. nickireson
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    nickireson Junior Member

    Im am completely unfamiliar with prepreg composites, its benefits, and even how it works
     
  4. nickireson
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    nickireson Junior Member

    So I did a little looking around. Pre preg is just carbon with resin and hardener already added, and you just bake it? Im not seeing how there would be any difference here?
     
  5. War Whoop
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    War Whoop Senior Member

    Sir they have taken all the fun out of it, And Yes it is basically a resin and hardener impregnated fabric , But a very sophisticated resin system and the strongest parts imaginable are built from these materials, nothing else is even close.
     
  6. nickireson
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    nickireson Junior Member

    I see. I saw a youtube vid about a guy that makes his own pre preg and just freezes it...pretty cool!
     
  7. cosborne
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    cosborne Junior Member

    Just a warning, you don't want to put metals in contact with carbon in a marine environment. You'll need to put a layer of glass between the two.

    With that being said, you may not want to use a biaxial sleeve to do this. Also, keep in mind the finish work necessary will be pretty crazy if you don't mold this.

    My suggestion as a composites manufacturer with an engineering staff...

    Build a mold and infuse it. You'll be able to handle more production, add in the glass, have a beautiful finish and best of all it's faster.

    I don't see any benefit to using kevlar. I'd consider doing some engineering if I were you. Otherwise you'll end up making a bunch of parts that don't work. There are also a few companies out there that can do it for a reasonable price and handle the engineering.
     
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  8. Herman
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    Herman Senior Member

    Also, I would integrate as many functions as possible into the part. I would probably skip the aluminium castings / parts and go for a 100% composite part, probably ending up with carbon and perhaps some glass.
     
  9. cosborne
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    cosborne Junior Member

    He makes a good point. If the metal components are not load-bearing then definitely try to eliminate them. It will be quicker and less expensive to infuse the whole thing without those components. If the components are load bearing I would keep them and infuse them into the part with a layer of glass separating them from the carbon. The reason for this is without engineering to determine the loads you don't know how much the carbon will have to take. Metal works great for these situations where you have an undetermined or inconsistent load.
     
  10. nickireson
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    nickireson Junior Member

    Well I am definitely no engineer. I know that (here come the technical terms) the poles take alot of abuse from some pretty heavy riding, but the stock ones are made of simply SMC fiberglass, so it is entirely possible, and maybe even more cost efficient for me to do it, once I have completed the mold making? Since I dont have the experience or money to have the part properly engineered, I will have to use so much carbon that it will be overkill I suppose. What is a basic layup schedule that will be light but almost indestructible?
     
  11. cosborne
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    cosborne Junior Member

    Unfortunately, light and almost indestructible don't go together. The reason most composite products are engineered is that the finite element analysis will show exactly where the loads are. In those areas, you can add foam or remove material altogether.

    With all that being said... if you're willing to go out there and potentially break a leg, you may want to try a structural foam 5ish pounds with 4 layers of uni @ 0, +45, -45, 0. Something like this http://www.carbon-fiber.us/12oz-unidirectional-carbon-fiber-fabric-yard-p-993.html

    I don't know a lot about your part but that's my best guess. Could be totally off base and I'm sure someone else here can give you some better insight. I have some ebooks and such I can send you if you want to learn about what's involved with the molding since that's your first hurdle.
     
  12. AndrewK
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    AndrewK Senior Member

    Just buy ready made filament wound tubes.
     
  13. nickireson
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    nickireson Junior Member

    I have done some very mild molding before, but would certainly appreciate any knowledge or info you can pass on! One of my favorite things about composites is that there is always always more to learn. How do I get these ebooks?
     
  14. cosborne
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    cosborne Junior Member

    Sorry to leave you hanging there... got busy today. Shoot me a pm or email with your email address and I'll send them over. The main one you should read is pdf format. I think the other one is too but could be word.
     

  15. nickireson
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    nickireson Junior Member

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