Fibre vs Carbon Fibre vs Kevlar

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Arowin

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I've just found a good site in NZ that sells fibre glassing gear and noticed they also sell Carbon Fibre and Kevlar sheets...
As I'm still new to this stuff, could anyone outline the benefits or is it just:

Fibre: Low cost, weak, easy to work with
Carbon Fibre: Medium cost, strong, medium difficulty
Kevlar: High cost, really strong, high difficulty?


Also, could someone outline what the following means:
* indented overnight, all combinations on request.
* 300g Twill Weave 600mm wide $45.00LM
In particular, "Indented overnight" and "LM"

Having a look at ResinGod's post (http://405th.com/forums/index.php?showtopic=10108&hl=) it looks like carbon fibre needs vaccum sealing as well, I assume kevlar is the same?


http://www.nzfibreglass.co.nz/

Cheers guys
 
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By fibre i think you mean fiberglass? right?
Anyways i would add "very strong" on carbon fiber, because it's stronger then steel.

-Fin(n)ish

EDIT: also carbon fiber is super light... when we compare it to kevlar for insstance.
 
Finnish_Spartan said:
By fibre i think you mean fiberglass? right?
Anyways i would add "very strong" on carbon fiber, because it's stronger then steel.

-Fin(n)ish

EDIT: also carbon fiber is super light... when we compare it to kevlar for insstance.
is kevlar not bullet proof that would be a good feature for every day life
 
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korekillerking said:
is kevlar not bullet proof that would be a good feature for every day life
Kevlar under normal circumstances is "bullet resistant". My understanding of it is it's basically plastic thats layered quite a few times over.
 
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ODST-RAGE said:
I thought carbine fiber not that strong or am I just thinking of a carbine fiber hood :cautious:
your thinking of the hood :p
 
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carbon fiber is extremely resistant to heat, is very strong, and lightweight.. plus it looks cooler than fiberglass. one thing about carbon fiber though, is when it does "break" it tends to split. this can also be prevented by using at least 2 layers of bi-directional weave, one layer you want going vertical and horizontal (like +) the other layer diagonal (like X) the result is 4 times as strong, and less chance of splitting..

the same method can be used on regular fiberglass to reinforce it, but it is still weaker than carbon fiber.

as for Kevlar, i have not used it before, so i can really say.
 
LukeTrocity said:
Kevlar under normal circumstances is "bullet resistant". My understanding of it is it's basically plastic thats layered quite a few times over.

Not so. Kevlar isnt bullet resistant. It was created to withstand explosions and knive's. However the plate at the front of kevlar armour is bullet resistant.
 
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Fiberglass is incredibly strong when layered, but is the weakest of the 3.
Carbon Fiber is expensive, but insanely strong and light, and would make a tough armor piece (provided the cash)
Kevlar is for war. enough said.


Cost goes like this: Fiberglass<Carbon Fiber<Kevlar

so i dont know if we should be making bulletproof suits JUST YET.

wait a bit until the covenant come :p
 
Tensile strength. Hardness. Curing time. Tools necessary. Toxicity.
These are good properties with which to compare these materials.. and unmentioned in this thread. :(
 
Fiberglass is the easiest to work with, and has decent strength and is fairly light, and by far the cheapest.

Carbon is harder to work with, and is incredibly strong and incredibly light.
The problem with carbon is that since it's black you can't tell if it's been properly wetted out with resin, because unlike fiberglass, you can't see it change color when it's saturated with resin.
Also, carbon is conductive, and flammable, which means that if the electrics of your suit short to the suit, it's going to catch on fire.

Kevlar is very hard to work with, and is very flexible, and stronger than fiberglass.
Unlike both carbon and fiberglass, Kevlar is pretty flexible once it's cured, and will bend quite a bit before it cracks (unlike fiberglass and carbon)
Also Kevlar is very difficult to cut, and for lack of a better term gets "gummy" when you cut it, and so you need specialized cutting shears just to cut it.

Personally, fiberglass seems the best choice for making armor, because it's cheap, and very easy to work with, and if you make a mistake it's not too incredibly costly (compared to if you had made it out of carbon or Kevlar).

Also bullet proof vests are make of layers of Kevlar fabric which are stitched together, not resined together. They're kinda like glorified nets which catch bullets.
 
This is the sort of discussion I was hoping for :p

As far as construction goes, are they still the same for each type? ie, cut into strips -> cover with resin -> repeat.
 
Yes for armoring the process would be the same more or less for carbon fiber kevlar and fiberglass.
But I have a question:
Why would you ever need that much strength for your armor when you can get all the strength you need from a layer or 2 of fiberglass?

Also resined kevlar isn't bullet proof, it would just be too rigid, you can easily put a hole through a kevlar canoe (trust me my dad did it up in the boundary waters). The kevlar vests that cops use are not resined they are just layers of kevlar designed in a way that when a bullet hits it the force of the impact will dissipate across the top few layers of the jacket.
 
i read about kevlar somewhere and heard its obviously the best choice but the most expensive, but if youve had average experience in crafting and stuff it can be relativle easy to apply
 
basically, kevlar is for those who want to say they have a kevlar suit.

go for fiberglass. save some cash.
 
Something to consider is the requirements. As Vrogy said, considering tensile strength and the forces the part will be exposed to plays a big role. Carbon fiber has a very high tensile strength for it's weight.. But for that strength you will pay out the nose. There is a global shortfall in supply for carbon fiber due to the increased demand from the aviation industry (Boeing's 787 is almost all carbon fiber). Kevlar's principal advantage is its abrasion and impact resistance. You need special shears to cut the stuff, as it dulls conventional scissors quickly. Kevlar is also expensive. Fiberglass, available in two varieties (E glass and the harder to find but stronger S glass), is a great general purpose composite. It's light and strong, but the cost is manageable. If you don't need the ultra low weight for a given strength, go with fiberglass. Remember, the strength of a composite layup is in the reinforcement (ie. the carbon fiber or fiberglass) the resin is just there to hold everything together. Too much resin and you end up with a brittle component. If you wish more impact resistant, put a single layer of Kevlar on the face of the part. That can increase strength of the part after impact by up to 90%. The trick is to make the reinforcement thicker in high stress areas, and thinner everywhere else. Just so everyone knows, and doesn't think I'm trying to be condescending here, I have dabbled in composites, and have done quite a bit of research on the topic. I was looking into building my own airplane, but fuel prices have made that impossible for quite awhile; like 'til I win the lottery. -Semper Fi
 
one of the major issues your going to face is that most kevlar comes in a pulp for not fiber sheets so it has to be pre-mixed with other resins and hardeners as for carbon fiber it doesnt have to be vacuum molded but it does help out a lot with the final product "removes air bubbles etc.." plus when your using carbon fiber sheets you will soon learn that carbon fiber does not like to conform to tight angles and deep ridges which is where the vacuum bagging helps because when you introduce a negative pressure to the form it kind makes the carbon fiber sheets mind thier manners and go where they are supposed to. Now as far as fiberglass its a wonderfull thing if you dont have the funds for carbon fiber and if you layer it right everything will work out but I myself prefer the impact resistant nature of layered carbon fiber over fiberglass " had to remold too many body kits due to customers curbing thier cars" all in all though if you dont mind spending the extra $$$ carbon fiber is the way to go for durability.

and thats my .2
 
To answer the two questions from the first post.. "LM" is "Lineal Meters".. if you know the roll width, this is the price per meter of that material on a roll.

I'm not sure what "indented overnight" means, unless it's not a weave, and the indents are referring to forming of the material into a mat.. Basically compressing it, and the "combinations" may refer to different material layers to build it up.
 
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