Carbon Fibre Thickness

Discussion in 'Materials' started by Westcountryboy, Feb 12, 2012.

  1. Westcountryboy
    Joined: Jan 2012
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    Location: Cornwall

    Westcountryboy Junior Member

    hi there

    Could anybody here give me a rough idea of the strength of carbon fibre.
    I understand it is very important to allign the fibres with the forces involved but is there a RULE OF THUMB with the thickness of material ?

    For example say 1 mm of uni for light loads upto 100 kg
    or 3mm for loads upto 500 kg.

    I do understand this is like asking how long is a piece of string but what I am after is some rough guideline from people who use the material alot and can give me a rough idea.

    I have looked all over the internet and cant find anything relating to the thickness of the material.

    I have another post in the design section, I am looking for help to design a curved beam which will support a mainsail track. I need to find out how much carbon fibre I will need.

    Thanks in advance

    Tony
     
  2. tunnels

    tunnels Previous Member

    What sized boat ?? dinghy ? cruising boat 36 foot long ? what ??
    How big is the mainsail track ??
    length and width how is it mounted flat on a surface or raised ???,
    want drawings or pictures what ever !! The more info you provide the better and quicker you will get a answer !!:D
     
  3. Westcountryboy
    Joined: Jan 2012
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    Location: Cornwall

    Westcountryboy Junior Member

  4. groper
    Joined: Jun 2011
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    Location: australia

    groper Senior Member

    take the time to read all this carefully, it will tell you everything you need to know - ignore the honeycomb core, the principals and theories are the same even tho your using plywood core. Focus on the beam bending equations, the carbon strength is givne in the appendix.

    http://www.hexcel.com/Resources/Dat...eets/Honeycomb_Sandwich_Design_Technology.pdf

    Be careful tho, you need to allow for safety factors - design the beam with higher than calclated loads. And you need to consider dynamic forces - ie what happens to your 500kg load when you gybe and the whole rig slams across to the new tack? - 500kgs static becomes a hell of alot more than that in this dynamic situation.
     
  5. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    With carbon you are trying to make things light and strong. Light and strong requires engineering and a high level of craftsmanship.

    For a main sheet track you want strong....not light. Why carbon ???

    Use your intuition and overbuild.

    Also consider that if this is a mechanically fastened track all the holes you drill thru the carbon will affect the finished product.

    The secondary bond between the deck and traveller will represent the ultimate strenght of the whole system
     
  6. Eric Sponberg
    Joined: Dec 2001
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    Location: On board Corroboree

    Eric Sponberg Senior Member

    Hi Tony,

    You need the following help. First, download a free copy of Eric Greene's "Design Guide for Marine Applications of Composites" (scroll down, lower right corner):
    http://www.ericgreeneassociates.com/articles.html

    It tells you a lot of what you need to understand engineering of composites. Of course, one of the most difficult numbers to come by is the laminate thickness of any given piece of material, whether glass or carbon, or unidirectional, knitted, or woven. Fiber content also plays a huge part, lower fiber content laminates are thicker than higher content laminates. If you are doing a wet lay-up, you will get thicker laminates than if you vacuum bag. Resin injection and pregreg laminates also have different per ply laminate thicknesses. Then, when you mix fabrics, who the hell knows what you have. So if you can, try to obtain samples of fabrics as you study composites--measure them with a micrometer or caliper--that will at least get you into the ballpark.

    In addition, you can also download a free copy of the Vectorlam software from Vectorply. It is a spreadsheet program, free to download, but you do have to register as a user. Get to know this program--I use it whenever I do composites engineering. The program has a huge database of all sorts of materials and fabrics, including their ply thicknesses, and it will let you create laminates, even with cores, and tell you the weight, strength, stiffness, thickness--whatever you need to know--about the laminate you are designing. You can also do laminate comparisons on any given set of parameters. It is hugely powerful. It will also let you enter and store additional or revised fabirc or laminate data that you create yourself. It takes a little while to understand how the program works, but once you have it down, it is a really good program. Here's the link:
    http://www.vectorply.com/lamdesign/vectorlam_sw.asp

    Finally, Gurit--SP Systems is a good source for materials characteristics, properties, and knowledge. Their materials are widely available all over the world. Here is a place to start, and you can explore their website for more information on their materials and processes:

    Gurit Guide to Composites:
    http://www.gurit.com/composite-materials-and-technology.aspx

    I hope that helps.

    Eric
     

  7. Westcountryboy
    Joined: Jan 2012
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    Location: Cornwall

    Westcountryboy Junior Member

    Thanks Guys

    This is great information

    Cheers

    Tony
     
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