I see there's been a rash of recent carbon fiber all out bonanza with the FC. I think this is great, I think it could wind up carrying on the cars for years, as it grows to replace more and more hard to find parts. But the thing is... I really don't know how carbon fiber is made. I don't know what it feels like, why it has that certain look, how strong it is, how light it is, or most importantly: What it is. And it has to be molded? Is there an FAQ on it somewhere?

 

http://www.bryanf.com/info/carbon.htm

Steve

 

Carbon fiber is a FRP - Fiber Reinforced Plastic. For that matter, so is fiberglass. Either way, it's just plastic resin that has fiber (in this case carbon fiber aka graphite) weave in it for strength. The advantage of carbon fiber over other FRPs is that you can go really light on the resin (plastic) and the layup (the layers of fiber weave) and maintain strength.

Some people think it looks neat. Personally, I think it's tacky, and I'd paint it.

There's also aramid (Kevlar(tm) ) fiber. All that is is carbon fiber with some aramid fibers in there too. Kevlar(tm) by itself is very stretchy and floppy and not very structural, however it will help hold carbon fiber panels together when they break. When you see a CF car in an accident and see the panels flapping about yet still attached, it's Kevlar(tm) in the weave that is holding it together.

 

The previous guys answered quite a bit. For more info, use a search engine and look up topics under composites.

The carbon fiber products that you see are composed of two things...raw carbon fiber and the resin. In the raw state, carbon fiber is merely a black looking thread. You can purchase carbon fiber as a spool of thread or in a woven pattern. Most often, for the "eye catching" appearance, you will see the woven pattern.

www.carb.com
www.uscomposites.com

When the finished product is made, the surface should feel smooth. Carbon fiber is very strong. In some cases, stronger than metal. It is also VERY light. That is why is it used as body panels (or entire chassis pieces) on race cars.

 

Kevlar cloth is NOT floppy. Actually, its stronger than carbon fiber. It is also lighter, and MUCH more impact resistant. But it isnt quite as stiff as carbon fiber. The reason kevlar does that in an addident is the fibers are very difficult to cut. Carbon fiber can be broken, kevlar cannot.

Now has anyone else in here actually worked with kevlar first hand?

 

I used to work with resin impregnated Kevlar, (which requires baking to set up) but never with loose Kevlar sheet and liquid 2 stage polyester resins.

With the RIK you could cut it with razor blades (you'd get about 6 decent cuts per blade) or high pressure water jet. I never liked the way it looked though... too much green/yellow, but maybe it was just the brand of RIK we were using.

 

Kevlar is slightly stronger than carbon fiber in tensile strength (pulling a fiber until it breaks). However it is substatialy weaker in compression (say you had a rod push it together until it breaks.) One main advantage of carbon fiber is that it doesn't stretch much and you can make a very stiff panel by utilising this feature.

Considering the cost, I don't see much advantage using advanced composites (carbon fiber, kevlar, etc.) for fenders and hoods (especially when aluminum hoods are cheap) unless you are racing. I thought I was going overboard spending $75 on an aluminum hood to save 20lbs. Is CF mostly for appearance?

 

First off, let me say that I dont use polyester resins. They are **** compared to the aircraft grade epoxy I use. That epoxy also does not require baking like pre-pegs.

I have a pair of $80 scissors I use to cut the kevlar. They work quite well, but it still isnt easy to cut. And it is a BITCH to make clean cuts after its layed up. I need to go get me some razorblades so I can clean up the kevlar 2nd gen cooling panel I made.

Junior-coyote, did you ever think about how easily aluminum dents? Now think about carbon fiber of kevlar. It doesnt dent. It if gets hit hard enough, it might crack. But say good bye to door dings with composite body panels.

BTW, kevlar is about 30% lighter in weight the cf. Not not as stiff, but MUCH more impact resistant and wear resistant. You can beat on it all day, and it will be just fine.

The radiator panel Im working on is a pretty bright yellow. Not green at all. It was probably that color from the type of RIK you were using.