Carbon fibre structure with HDPE/ABS frames

Discussion in 'Materials' started by Luis Santos, Mar 3, 2018.

  1. Luis Santos
    Joined: Mar 2018
    Posts: 2
    Likes: 0, Points: 1
    Location: Berlin

    Luis Santos New Member

    Hi all,

    First of all, I would like to thank everyone on this forum for all the help you provide for everyone who needs! I am new here but I have learnt a lot already.

    I am designing a small jet kayak (4m long for two people, 15hp engine). I want it to be as light as possible, so I have chosen to make it out of carbon and carbon/kevlar hybrid, all with Epoxy resin. The bottom made of the hull with the hybrid plus a 2mm Soric honeycomb core, for resisting the impact of the rocks, and the rest made of carbon fibre.

    I am making a reinforced structure, with longitudinal and transversal frames, this is something required for this project to install bigger engines in the future. After placing the frames, another layer of carbon will cover the whole structure inside the boat. My question is about the material of the frames. I want to use HDPE or ABS, as they are easy to machine, cheap and can be screwed (some additional features needs to be fixed with screws). I am afraid of combining these materials with carbon fibre, maybe the thermal expansion will be a problem.

    What do you think of this kind of structure? Any other considerations for this project? Which one would be better, ABS or HDPE?

    Thanks again and best regards,

    Luis
     
  2. gonzo
    Joined: Aug 2002
    Posts: 12,834
    Likes: 255, Points: 83, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    If you are looking for light as possible, both HDPE and ABS are poor choices. It will defeat the expense of carbon/kevlar and epoxy. If you are planning on a hull that has to resist impact with rocks at high velocity you should be considering toughness rather than tensile and compression strengths. In that aspect fiberglass is superior.
     
  3. Luis Santos
    Joined: Mar 2018
    Posts: 2
    Likes: 0, Points: 1
    Location: Berlin

    Luis Santos New Member

    Hi Gonzo. Thanks for your reply. You are totally right, all the frames made of HDPE turn out very heavy. I am thinking about making it of foam, and the parts that will be screwed and exposed I can change to HDPE. Do you think that could work?
     

  4. gonzo
    Joined: Aug 2002
    Posts: 12,834
    Likes: 255, Points: 83, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    I wouldn't use HDPE anywhere in the structure. What do you need to screw on that can't be glued on? If you are designing a high-tech structure, go all the way and use modern adhesives.
     
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