CARBON FIBRE

[Mikhil]

Our team is 3 yrs old.
We want to introduce carbon fibre this year.
Basically we wanna get a feel of carbon fibre dis yr b4 actually using it.
I thought we'll start of wid CF steering wheel and A-arms.

What are the advantages of a carbon fibre airbox and the specifications of the CF for building one?

-Thanx

[Mikhil]

Our team is 3 yrs old.
We want to introduce carbon fibre this year.
Basically we wanna get a feel of carbon fibre dis yr b4 actually using it.
I thought we'll start of wid CF steering wheel and A-arms.

What are the advantages of a carbon fibre airbox and the specifications of the CF for building one?

-Thanx

[Rellis]

good luck

[Chris Lane]

Make sure you do your research before going anywhere near CF wishbones.

If you are that inexperienced with it, I would NOT be making wishbones out of it. Start with simple things like we have: covers, plenums, etc. ie. non structural.

[Mikey Antonakakis]

I can't pretend like I know this from experience, but I'd imagine that the advantages of a carbon airbox would be weight, and it looks sweet. The carbon doesn't need to be extremely strong, but needs to withstand backfire.
I'd like to make our final intake this year out of carbon fiber, so I'm also interested in what people have used.

[exFSAE]

Rly? Iz dat wut u gon do wid it? 4 ril?

For what its worth on airboxes, you'd think a carbon one would be super stiff.. but it's surprisingly easy to make really flimsy geometry as well.

[drywater]

@ mikhil
first of all please dont write in that sms language,i know you are an indian.
we are also a indian team ,we are manufacturing our 7th car but we haven't used carbon fibre anywhere,primary reason being the availability of carbon fibre in india,moreover facilities for curing of carbon and manufacturing products(e.g drive shafts) aren't available here easily.Further for teams like us ,a minimum of 1-2 years of research is needed before we start using carbon fibre.

[bahous]

as a first CF project, try to do it on non-critical components such as the steering wheel, body panels, dashboard. applying it to critical components requires much more knowledge and reading is not enough (i'm not saying you can't successfully design something from a self-thaught process). i'm saying that based on what i heard on my team and what i've seen. i'm taking a class this semester called 'Mechanics of Composite Materials' and there's a lot of concepts that are not always included in books or online.

[SamB]

Stay away from carbon wishbones for now! Stick to bodywork for the first few years until you get used to using it. You need to make sure you have somewhere to actually make the panels - that depends on what method you are using. You can make it yourself using a wet layup method, or use prepreg which is more complicated and I'd reccommend against using it in your fist few attempts. Mainly becuase you need a decent autoclave.

If you really want to use that much carbon for intake etc, look at buying one. Depending on your budget, dont rule out SLS for the intake. You can produce some amazing shapes but it costs!

[screwdriver]

I strongly agree with what's been said above. Stay away from anything with small radii and anything that is critical to the car.

For a steering wheel, only a wheel cut-out of a plate is possible, stay away from ergonomically formed grips and half-shell constructions.

I would start with the bodywork. It offers a big playground without any structural constraints.

Regarding the air-box: reconsider. Intake and airbox need a very good interior surface. This means that DIY molds won't do, unless you are prepared to do nothing but sanding them for weeks. You have to consider getting molds milled out of mold-foam or AL. This of course limits the complexity of the shapes you can use.

If you separate them from the airbox-body, the restrictor, throttle-body and intake are quite easy. They only require a simple turned mold.

We had our molds for these parts made of AL and I found removing the parts from the mold a pain in the ass. Maybe coating or painting the molds could help.

[MalcolmG]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
Regarding the air-box: reconsider. Intake and airbox need a very good interior surface. This means that DIY molds won't do, unless you are prepared to do nothing but sanding them for weeks. You have to consider getting molds milled out of mold-foam or AL. This of course limits the complexity of the shapes you can use.

If you separate them from the airbox-body, the restrictor, throttle-body and intake are quite easy. They only require a simple turned mold.

We had our molds for these parts made of AL and I found removing the parts from the mold a pain in the ass. Maybe coating or painting the molds could help. </div></BLOCKQUOTE>

Although I agree that doing the intake from carbon might not be a wise way to dip your toe into the water of composites, I think you're greatly over-exaggerating the difficulty in creating good moulds. There are a vast array of techniques for creating moulds, and I certainly feel you can make a mould that will produce a quality part without "weeks and weeks of sanding". The real issue with doing an carbon intake as your first attempt at composites is that you need to choose the materials and manufacturing technique wisely in order to produce a good part which is airtight and strong/stiff enough to stand up to fluctuations in vacuum at elevated temperatures without failing.

Screwdriver - the nice thing about aluminium moulds is that you can get them to release by rapidly cooling the aluminium, by perhaps heating the whole lot up, then putting them under running water. The aluminium cools more rapidly than the carbon and shrinks. If it occurs quickly enough then you can hear the aluminium releasing from the carbon and it pops right out. I don't think painting will be any better than a highly polished aluminium surface

[screwdriver]

Dunno. Maybe we used a weird alloy, or the mold wasn't treated correctly before working.

Well all I can say is that you should give it a try. It's definitely worth it.

[Adam G]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by MalcolmG:

The nice thing about aluminium moulds is that you can get them to release by rapidly cooling the aluminium, by perhaps heating the whole lot up, then putting them under running water. The aluminium cools more rapidly than the carbon and shrinks. If it occurs quickly enough then you can hear the aluminium releasing from the carbon and it pops right out. I don't think painting will be any better than a highly polished aluminium surface </div></BLOCKQUOTE>

The ease of release could also be due to the opposite coefficients of thermal expansion of the two materials. Aluminum has positive thermal strain when it is heated (positive Coefficient of Thermal Expansion) while the carbon has a negative thermal strain due to its negative value for CTE.

I agree with those who suggest staying away from structural members for first attempts at composite layups. If you are on a tight budget you can also get some experience with layup procedures by practicing with fiberglass before you step up to more expensive carbon fiber.