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There is no info i can find on their website, http://www.ccc-fabrics.com/en. The composite industry seems pretty strange in its distribution channel. Anyone has any tip? I am attracted to their products because they are used in certified planes. Thanx for reading!
Hexcel products are widely used in the aerospace industry as are several others. I would think you can ask your supplier who weaves their fabric and they would provide the necessary info.....??Quote:
Originally Posted by wantobe
If you look up the materials properties, carbon fiber is carbon fiber. The carbon fiber fabric producted by one manufacturer is not hugely different from the fabric producted by another manufacturer for the purposes of a homebuilder since you and I do not have a large autoclave and automated equipment. What differentiates different rolls of carbon fiber cloth for us is the weave style and the number of strands in each thread of the weave. Different weaves carry tension and compression slightly differently and most importantly, form around corners and curved shapes better.
I would suggest going to the Hexcel web site and doing some reading. You will want to understand the weave styles. Carbon fiber strands provide their best mechanical properties when they are perfectly straight, and weaving has the threads bend around each other. And the strength numbers provided are going to be modified by embedding the cloth in Epoxy and maybe using it as the facing of a core material. All of the info is available online but you will be well served by purchasing some fabric, core, and epoxy, and some 50lb or 60lb sand bags. Make panel and load it up. You will find what you see very interesting. Then start doing math.
Best of luck,
Wes
N78PS
Thanks for the replies. I checked out hexcel, and downloaded and read HexForce_Technical_Fabrics_Handbook.pdf. Page 30 title "Aerospace Carbon Fabric Construction Data", and page31 "Commercial Carbon Fabric Construction Data". The yarn used in aerospace section is "T300 3K", yarn in commericial section is "3K Carbon, 33MSI". What is the difference? Should we use aerospace grade only?
Aircraft Spruce supplies Style 284 bidirectional carbon 2/2 twill, 5.7 oz/SqYd. This product is in the above commerical section of Hexcel. So it seems Aircraft Spruce is supplying commerical grade for airplane homebuilders. Is this a problem?
Nope. Build a test article and load up the sandbags. Say 1/4" core with one ply of carbon and epoxy on each side. Then report how strong it was.
Best of luck,
Wes
Aircraft materials require a paper trail. I guess it depends on the application but if I was reasonable assured of getting the same stuff then I'd probably use it. Piece of paper doesn't make much difference otherwise......Quote:
Originally Posted by wantobe
This is a bolt and wrong statement. There is a wide range of carbon fibres on the market. Looking just into aerospace grade the range is from the most commonly used Toray T300 and HTA fibres which are mainly used in woven fabrics via high strength fibers T800, T1000 to ultra high modulous PAN fibres (M55J, M60J) and the pitch fibers from Granoc YSH-50, -60,-70,-90 and Mitsubishi Dialead K13C2U, K13D2U and....Quote:
If you look up the materials properties, carbon fiber is carbon fiber.
Not all of these fibers can be woven, some, the stiffer ones have to be processed as unidirectional prepregs or even directly as yarn roving coming from the bobbin (by filament winding, automated fiber placement...). For aerospace use the traceability of the raw material must be ensured. This is given for the aerospace grade fibers and their woven fabrics. For homebuilt purposes the T300 or HTA based fabrics(plain weave, 2-2 twill, ...) are affordable and sufficient. The higher grades require more processing skills, are more expensive and you will pay up to 3 k USD for the ultra high modulous fibers.
So, it is not true that "If you look up the materials properties, carbon fiber is carbon fiber." The only thing they all have in common is their colour: black.
Well you are correct if you believe that folks from Airbus and Boeing are looking at this thread for advice. I have to confess that I am assuming that the average reader and poster here only has access to US retail type distributors and does not have the budget for the higher end materials that you speak of.
The carbon fiber fabrics that are available through Jamestown Distributors, Aircraft Spruce, etc., are essentially all the same.
Are there inexpensive alternatives available for home building aircraft in Europe?
Best,
Wes
N78PS
The main difference between carbon fibers is the modulus and ultimate tensile strength. A "standard modulus" fiber runs around 32 MSI and 500 ksi ultimate. An "intermediate modulus" fiber runs 40 MSI and 700 ksi ultimate. When selecting a fiber system for transport aircraft, designers look for maximum perfromance per lbs of structure so the strength and stiffness matter considerably. For homebuilts, carbon fiber with "standard modulus" of 32 MSI is fine. The materials sold by Spruce are probably at the low end of performance and cheaper and works fine for homebuilt projects.
When woven, the final strength of a fiber system is knocked down. If the weave is 50% in each direction ( warp and fill), then there is an immediate reduction of half the potential strength so for a 500 ksi fiber, you drop strength to 250 ksi. The the resin volume is ~50% so that knocks strength down to 125 ksi. Throw in poor compaction and porosity for a wet contact layup and you are down to maybe 80-90 ksi ultimate. So bottom line is that there is a huge difference between fiber properties and final laminate strength for home layups. And the lower cost carbon fiber works fine for most home applications.
Bob H's explanation of carbon fiber-reinforced composite strength is very clear. Thanks!
If you are going to buy small quantities of dry fiber, whether glass or carbon, there are small specialty houses that supply materials cheaper than buying from large prepreggers like Hexcel with all their overhead costs. Composites Specialists in Laguna Nigel, CA is one. These firms buy up excess materials and resell at prices generally much lower than any major supplier can match. And they will sell smaller quantities, but not like 5 yds of glass, which is very small; more like 25-50 yds at a time.
The large companies buy fibers from manufacturers, weave them and impregnate fabric (prepregging) with resins and freeze it for shipment and storage. These are mostly used by commercial fabricators to make aircraft parts and the resin systems cure at 250-350F intended for autoclave cures at 100 psi. Prepreg is far too expensive for home use and overkill for most experimentals. It provides close control over fiber/resin volume and enables use of more toughened resins that absorb impact energies better than room temp curing resins used at home.
Fibers are coated with a sizing which enhances the bond to resins and it does have a shelf-life around 2 yrs for max performance but for homebuilts, any minor reduction in mechanical properties is probably negligible, so even old fibers will work ok. So bottom line is you can get quantities of woven fabric at reduced prices from small resellers.
I came across Bob H's post during a recent google search. Bob is correct, we are re-sellers, distributors and have a weaving facility and warehouse in Canada. We have 2 warehouses in Southern California. Primarily, we sell dry good reinforcements both FRP and Non-FRP. We sell smaller quantities; which can be less expensive (compared to min buys) and have better lead-times. I share an office with the Principal of Composite Specialists and they are one of the principals I represent. If anyone needs assistance please email me at Greg@G2Technical.com.