Hi,

I need some info about carbon fiber use on Formula 1 cars. I know that they are lighter, stronger, and stiffer than steel. What I want to know is... during a crash, do they just simply break away into small pieces instead of bending?

I saw this on TV.
Lets say an F1 car goes nose into a wall.
The CF starts to break into smaaaall pieces like dust and the car goes further the more resistance it gets.
So practicly the CF is slowing it down instead of just bending and making the car stop completely.
Which is does with CF too but not that hard.

Quite hard to tell, easiest is to google around for the discovery channel episode. Can't remember which program it was on though ...

Whel carbon Fibre breaks into a hundred thousend smal pieces resulting in the cloud of carbon dust.
This is the sighn of the carbon taking the impact away from the driver

But is some areas the carbon is thicker becaus how thicker the carbon is the stronger.
The carbon around the cockpit is the thickest and therefore the strongest this is aclled the carbon fibre monococ is cell of high density and thick carbon.
So the car crashind and getting torn appart in a specteculair way is just so the driver is safe the carbon takes most of the impact

Quote :

As far as its strength and impact resistance is concerned, a good dry carbon part will be around 5-8 times stronger than steel - depending on the grade - and many times lighter. But the thing is with carbon fiber, when it finally does give out and fail, it usually does it in a most spectaular manner.

WHEN IT ALL FALLS APART…

When I was in the defence force back in my old land of Australia, the base I was posted on was the scene of an accident that involved one of our Blackhawks clipping a tree and going down at around 160 kilometres per hour. Around the site, an area of around ten square kilometers was declared as a biohazard zone; when it went down, a large part of the CF items and panels failed, meaning they basically exploded into millions of tiny carbon shards - some so small that they could have been directly inhaledby some unfortunate individual and shredded their lungs.

But it’s not just that they can be inhaled; once a cured carbon item has been broken, the edges become jagged and razor-sharp, posing another great danger to human life.

Because of this, many countries have totally outlawed the use of aftermarket carbon fiber on cars, yet they still allow it when it comes fitted from the factory, on cars like the new BMW M3. The reason being is that in an accident, your car could be turned into something of a slice-and-dice weapon that could cause much more destruction than it normally would without CF parts.

Iffy Source

Additionally carbon fibre being a layered woven fabriccy type thingamybob is extremely strong in one direction and totally pants in the other, this is why F1 suspension can take extreme cornering loads but buckles at the sight of Phillipe Massa bouncing across the rumble strip to get you, often giving up and running for the hills with Phil Lynot at the mere possible prospect of a lateral impact.

This might shed a bit of light on the subject. Not very scientific but gives an indication to how CF reacts compared to metals.


http://video.google.com/videoplay?docid=3741362681682291899


CF whilst stiffer and stronger than a lot of metals is actually quite brittle. This means it will tend to shatter/snap rather than bend.

If you want to look up the actual properties of typical CF take a look here:

http://www.performance-composi ... echanicalproperties_2.asp

Remember though that there are many types of CF and they all have different values of stiffness, strength etc.

Just take a look here to see how many different variants of CF there are:

http://www.matweb.com/search/MaterialGroupSearch.aspx


Here's a comparison with Steel and Aluminium:

http://carbonfibretubes.co.uk/technology.html

Quote from gezmoor :

CF whilst stiffer and stronger (tensile) than a lot of metals is actually quite brittle. This means it will tend to shatter/snap rather than bend.

Just what I needed! thanks XD

Here is a good video illustrating the shattering of the dry carbon in a modern F1 nosecone.

edit: Carbon fibre parts will occasionally bend or get kinks in them (particularly suspension wishbones in F1). Once they have a bend or kink they lose the vast majority of their structural integrity. Further stress is likely to cause catastrophic failure.

Quote from amp88 :

Here is a good video illustrating the shattering of the dry carbon in a modern F1 nosecone.

Good god whilst that was quite interesting to watch, that has to be THE single worst video production I've ever seen. All I wanted to see was the effects of the impact, not a shit load of text spanning around the screen lol.

Where people say it's 'thicker' carbon fibre, that often isn't entirely true. The honeycomb in the middle of two layers gets thicker, so the total thickness increases, but the actual level of CF will be about the same. The strength and rigidity are a function of this. Thin carbon fibre 2x2 twill sheet - say 3 ply - is actually very, very flexible and can absorb a lot of energy before breaking/cracking/shattering. But once you've got various types of carbon weave in various directions on either side of a paper or aluminium (or Nomex or Kevlar) honeycomb core it gains strength and rigidity at the expense of toughness.

F1 cars still fail their crash tests frequently, so it's clearly not an exact science.

Rear wing endplates on our car are either aluminium skinned with a thin aluminium honeycomb core or carbon skinned with a plywood core. This makes it strong/stiff enough to push on and to deal with the loads on the track, but keeps it far, far lighter than solid aluminium or carbon would be to acheive the same strength.

Isn't it made in a honeycumb form, which is strong but also collapsable?

Correct me if I'm wrong.

Also keep in mind that carbon fiber is just that, a fiber. You generally don't use it as a fiber, but woven as a cloth and in combination with a polymer (and possibly other fibers like kevlar). Epoxy is quite common, but polyester and nylon are also possible. It all depends on the application.

BlakjeKaas: The honeycomb is the stuff between the skins of carbon, not the carbon itself. The honeycomb has very little strength on it's own, but when bonded inside a skin generates a very strong, rigid section.

Kingfag: I've not heard of nylon polymers being used as a binding resin. I'm sure it's possible, and indeed used, but I'd only heard of epoxy and polyester forms.

Wet layed sheets of carbon fibre that are used for non-structural purposes in race and road cars are normally weak and fairly pointless, they have little advantage over other much cheaper composites or sheet aluminium other than they are a little bit lighter and look like carbon fibre (the real reason they are used so often), sometimes some strength advantage can be gained but if the component is intended to be stressed in any significant way it is not a suitable composite to be used. Carbon fibre has some disadvantages, it costs a lot more and is harder to lay in order to get the weave to look right, for the same reason anything left as bare weave can't really be repaired. The end result of this is that the cost of using senseless carbon fibre is huge, we produce are own GRP airboxes for approximately a tenth of the cost of buying an off the shelf carbon fibre one, and personally I think that when painted they look better anyway, most customers would rather put a couple of grand to better use than having a bit of bling nobody can see.