Fiber Glass to Carbon fiber conversion chart?

Discussion in 'Materials' started by SpiritWolf15x, Apr 5, 2013.

  1. SpiritWolf15x
    Joined: Apr 2010
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    Location: Vancouver, Canada

    SpiritWolf15x Senior Member

    Hey everyone, just a general information question this time. Does anyone have a conversion chart or does anyone just "know" the conversion when subbing in Carbon Fiber when dealing in fiber glass? Does anyone know the comparison between carbon and glass? IE: 8oz glass cloth can be replaced with "##" oz carbon cloth to save weight without compromising strength.

    Example 1: Building a rudder, using carbon fiber for reinforcing as opposed to glass mat.

    Example 2: Building a hull, using foam core but using carbon instead of glass to save weight but not sacrifice strength.

    Thanks,

    Wolf
     
  2. Herman
    Joined: Oct 2004
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    Location: The Netherlands

    Herman Senior Member

    No, there is no such sheat.

    Carbon and glass have different properties, in different respects, but they cannot be "scaled down" that easy. You will run into caveats such as laminate thickness vs impact resistance and buckling resistance.

    I suggest posting your project, and people might have suggestions.
     
  3. SpiritWolf15x
    Joined: Apr 2010
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    Location: Vancouver, Canada

    SpiritWolf15x Senior Member

    There actually is no project, I was just looking for general information. Maybe I wasn't looking for a conversion chart per-say as much as a strength chart for carbon fiber cloth thicknesses.
     
  4. Eric Sponberg
    Joined: Dec 2001
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    Location: On board Corroboree

    Eric Sponberg Senior Member

    You'll have to get the information from the different fabric suppliers. Gurit/SP Systems and Vectorply both publish data like this. At least, they do for the different fabric physical properties, but not necessarily for material strengths and moduli. Strength and modulus vary greatly due to the environmental factors during processing--lay-up and cure, as well as post cure for epoxy laminates, to say nothing of the fabrics themselves, plus the skills of the laminators and the weather during laminating day. A big driver in mechanical properties if fiber content. If you design to a 50% fiber content by weight but you are actually only getting 40% fiber content, then your mechanical properties are going to be way off, and you won't have the strength and stiffness that you need. You will also have more thickness due to the extra resin, and that compensates somewhat, but it also means that your laminate is going to be much heavier than you intend. When engineering any laminate, you have to take all these factors into consideration. There is no simple switcheroo to change from one fabric to the other--you have to re-engineer everything because ply thicknesses as well as strength and modulus properties vary so greatly.

    A good place to start to review mechanical properties of laminates is Eric Greene's book, "Design Guide for Marine Applications of Composites": Link: http://www.ericgreeneassociates.com/publications.html. Scroll down, it's the blue-green book in the lower left of the list. It's a free download.

    I hope that helps.

    Eric
     
  5. tunnels

    tunnels Previous Member

    Give me glass any day !!

    Give me glass over carbon any day !! unidirectionals in glass with bend a mile and not break admitedly not quite as stiff but more durable and robust in a everyday work situation !!:D
     
  6. Herman
    Joined: Oct 2004
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    Location: The Netherlands

    Herman Senior Member

    It all depends on application, Tunnels. Plenty of applications where strength/stiffness/weight is the driving factor over resilience/impact strength.
     

  7. tunnels

    tunnels Previous Member

    i still say give me glass any day over carbon !! resilience , robust and impact strength will win hands down and will get you home any day over something that breaks shatters and wont hold together !! but at least leaves a trial of broken bits to see where you been !! :D
     
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