Carbon Fibre wheels

[ringo]

This discussion just reminded me about the surtees accident; think he could have survived a hit with a carbon wheel?

The only problem i see with carbon wheels are manufacturing repeatability.
One wheel may be laid up different than the next, but i guess if carbon can be machined, which it should, there should be no problems.
I would also imagine a carbon wheel could have titanium strands incorporated in the weave for more toughness.
Also, as it concerns manufacturing process; since the wheel wont be forged or casted, the spokes could be made hollow to save even more weight.
Carbon wheel with a metal hub center as a precaution sounds about right for racing.

[noname]

I wonder as to the strengthening aspect as well.

If you watch the "brick drop" video, they throw a cinder block off a 6 story parking garage, and it bounces when it lands.

Comparing that to an unsprayed cinder block that crushes from a 6 foot height (on their demo DVD, not on their website) I think that it adds an enormous amount of impact resistance.

my guess is the liner just adds damping and helps in more even distribution of impact loads and thus improves durability of the system. it is not the structural component designed to take loads.

in case of wheel tire acts as kind of similar liner transferring the loads from tarmac to the rim.

One wheel may be laid up different than the next, but i guess if carbon can be machined, which it should, there should be no problems.

what do you mean by machining ? milling the block of composite ?

[ringo]

I wonder as to the strengthening aspect as well.

If you watch the "brick drop" video, they throw a cinder block off a 6 story parking garage, and it bounces when it lands.

Comparing that to an unsprayed cinder block that crushes from a 6 foot height (on their demo DVD, not on their website) I think that it adds an enormous amount of impact resistance.

my guess is the liner just adds damping and helps in more even distribution of impact loads and thus improves durability of the system. it is not the structural component designed to take loads.

in case of wheel tire acts as kind of similar liner transferring the loads from tarmac to the rim.

One wheel may be laid up different than the next, but i guess if carbon can be machined, which it should, there should be no problems.

what do you mean by machining ? milling the block of composite ?

Not a block, i was questioning if a wheel was made completely of carbon, then after checking the balance and tolerances; if it could be machined by small amounts to remove little imperfections and bring it to spec.

[Jersey Tom]

What happens if you spray them with this?

http://www.vortexsprayliner.com/index.php

Good chance it would melt from the brake heat. That's the other issue with "conventional" carbon rims (ie a fabric layup). Too much brake heat. Think you'd fail just about any resin you can find.

Doing a carbon-carbon deal like a rotor would hold up, but I have no idea how you'd manufacture that.

[noname]

Not a block, i was questioning if a wheel was made completely of carbon, then after checking the balance and tolerances; if it could be machined by small amounts to remove little imperfections and bring it to spec.

this way you would destroy fibers and composites do not like it.

there are other means of keeping composite design within tolerances, a lot depends on mold quality and, mostly, on craftsmanship of the people doing the job.

[riff_raff]

The one characteristic where metals perform better than carbon composite structures is in elongation. Elongation is the characteristic that defines how much a material will plastically "stretch" before it suffers a fracture failure.

Metals like aluminum or magnesium have excellent elongation characteristics, which means they will bend a lot before actually breaking. Carbon composite structures are much stiffer and lighter, but the margin between their bending and breaking limits is almost zero.

So for something like a wheel rim, that may get smacked against a curb, a structure that bends a lot before breaking would seem to be preferable. Even with a small unsprung weight penalty.

Regards,
Terry