Question for you gurus

Discussion in 'Fiberglass and Composite Boat Building' started by Cruizin, Mar 9, 2012.

  1. Cruizin
    Joined: Mar 2012
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    Cruizin New Member

    So I've always wanted to build a boat and hopefully will some day. I have a question for you guys. I want to take a c channel piece of carbon fiber and add some extra shape to it. Its 2" wide 1.5" deep and .0625" wall thickness. I want to create some free form bulges on the outside of it and add a foam on the inside to make it stronger. I would then like to make a solid epoxy shell and then paint it. Any suggestions on materials and how to go about it? I am an engineer and have access to all sorts of resources but have pretty much zero experience with this stuff.

    Thanks and any suggestions are very appreciated.
     
  2. Herman
    Joined: Oct 2004
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    Herman Senior Member

    What kind of answer do you expect when you do not even specify length, or type of boat?
     
  3. Cruizin
    Joined: Mar 2012
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    Cruizin New Member

    Its not for a boat but I am thinking the materials used to make a boat could be used to stiffen this piece of carbon up. Can I simply add fiberglass and epoxy to stiffen it up? What about a foam type filler any suggestions there? What about a gel coat that gives a transparent finish? Looking for techniques and material suggestions.
     
  4. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    Cruzin,

    If you want to stiffen up a carbon fiber channel you ought to use carbon. The carbonfiber is about 3 times as stiff as the glass, so you would need a lot of glass, it becomes a waste of the carbon. Would you just be better off using another piece of channel? Is there some reason why you need the carbon?

    Adding foam will do nothing to make it stronger, it doesn't matter what kind of foam.

    Actually if you want something stiffer can you use a rectangular section aluminum pipe? Anything with a closed section will be stronger than that open channel.

    If you can describe what you want to do with it someone can probably help.
     
  5. alan white
    Joined: Mar 2007
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    alan white Senior Member

    There are methods of creating stiff and light pieces using epoxy resin, fiberglass or similar cloth, and a foam core. Beyond that, the part has to be engineered at least to the extent that it maximizes the materials used in the process.
    However, no part can be designed from what little information you've provided.
    Gel coat is opaque. A clear coat of epoxy followed by an outer coat of a UV inhibiting varnish of some kind is used if the part is going to be subject to sunlight.
    The foam is very important for stiffness. Foam, resin, and cloth are all important.
    But how much thickness, and what exact formulations and types of products depends on the particular design involved.
     
  6. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Have you preformed any research into whatever you're attempting to accomplish and what type of "engineer" are you, a commuter train driver?

    A central beam, all trussed up is one approach, but with very obvious limitations, which any reasonable engineer would quickly pick up on, hence my question as to what type of engineer, you might be, as "the materials used to stiffen a boat" are engineering concepts, most pretty easy to comprehend.

    I'm not trying to be coy with you, but you've asked an extremely broad set, of very generic questions (which is quite un-engineer like) about a project, that might be a boat or might not, but one thing is for sure, we haven't a clue what it might be, it's role, load paths, duty cycles, use, expectations, etc.

    Maybe it would be best if you offered a bit more about the project and more specifics about your desires and goals for it.
     
  7. Cruizin
    Joined: Mar 2012
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    Cruizin New Member

    Mechanical Engineer. Its a product I'm working on and some what sensitive information. I'm somewhat familiar with bike frame construction and design with carbon but I didn't do too much on the manufactuing side just worked on the design of the tooling for the components.

    What if you wanted to use this piece of carbon as the back bone of something and add a bulge on the outside and something on the inside of the channel to add some meat and density. I was thinking some glass or maybe more carbon and maybe a foam type of filler??? Have any of you seen a nice composite gun stock? Like a manners or mcmillian stock? Some of your feedback has been good. Thanks for your help and looking forward to hearing more.
     
  8. tunnels

    tunnels Previous Member

    If you start with carbon you carry on with carbon !! If you make in glass you carry on in glass and what ever resin you start with you carry on with . dont try to mix things together ,99% of the time it never works like you are exspecting .
    Carbon has very little to no streach !! where glass has streach !!:?::confused:
     
  9. alan white
    Joined: Mar 2007
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    alan white Senior Member

    What are you asking? This kind of construction is already common. Surfboards, model planes, and so forth. It may be that your application would be original but even then, you could hardly claim originality if the technology already exists. Shapes are very hard to patent. New applications of existing methods of construction are usually considered obvious by the patent office.
    An exception might be something like a new laminated guitar sounding board (top), using foam, glass, and resin, especially if the shape is functional. Not as obvious since the goal is to create a new way to process sound waves. Some classical guitar tops are made with composite construction.
    Check out this link: http://www.premierguitar.com/Magazine/Issue/2007/Dec/Sandwiched_Tops.aspx
    Of course, something like an application like a rear view mirror housing for a car might be impossible to patent (though it might still be worthwhile to manufacture the product).
     
  10. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    Cruzin,

    If you want increased density forget the carbon channel, you are wasting your money.
    If you want to add shape and insist on the carbon channel, foam and fiberglass will work just fine, use styrofoam unless you want to foam to be rigid enough to transfer load, then use a polyurethane foam. Others will probably be usefull but I haven't looked at them in a long time.
    If you need stiffness use something other than a channel. You might as well just set up forms and strip plank with cedar, or pine or fir, making a closed box. coat with fiberglass if you want durability and additional stiffness.
    If you want light weight, use the strip planked shape as a form use a release film (packing tape will work as a low tech solution), laminate graphite cloth with epoxy. After cured, flip over the mold, add separator sheet, laminate the opposite side of the mold with graphite epoxy. After cure, remove all the graphite and bond the two laminates together.

    Did you have any other requirements?
    The last one will be much more expensive, but if thats what you need......
    Before you spend the money, there are multiple local libraries which are repositories for Patent information. Go do your own patent search for free. When I did I was shocked at the hundreds of similar/ exact duplicates that already existed.

    Good luck.
     

  11. Cruizin
    Joined: Mar 2012
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    Cruizin New Member

    You guys got me thinking. I went back to an aluminum tube cause I don't want to deal with it. The best way as you guys have mentioned is to design the entire part correctly from the get go. These guys have some interesting product though. Thanks for your help guys.

    http://dragonplate.com/
     
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