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I AM Intrigued By These CarbonFiber Wheels..Pic


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For primary structural members - most especially those that have high-consequence failure - I'm always concerned about partial vs. catastrophic failure modes. There's no plastic deformation mode for carbon-fiber. That is, say you're driving down the road at high speed and hit a rock. Metallic wheel, you'll get a elastic (ductile) failure, the wheel is bent, there's lots of vibration, you slow down and complain. Composite wheel, you hit the rock, catastrophic (explosive) failure, carbon fibers and resin all over the place, you have no wheel, you're in serious trouble. It's one of the reasons engineers designing military aircraft like metals for primary structures: put a cannon shell through a metallic structure, there's a slim chance it'll survive. Cannon shell through composites, no chance.

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as an ex pro road cyclist, we had numerous versions of carbon aero wheels. there were several designs that were stiff and others were not so. there was one manufacture where if we were on a rough road and i was stuck in the pack next to him, i would go elsewhere. i have been behind and beside several of those wheel where when the rider hit a small pot hole, ther wheel exploded and he hit the road hard. remember, these were 175lb guys at 30 mph, not several thousand pounds at 75-80 mph. the results were not nice. if designed with kevlar in the carbon cloth, it would give a little bit of a warning that something was wrong. i doubt that you could react in time in a car. i will stick with metal rims. tried and true.

 

jimbo

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IIRC Ayrton Senna was killed when his car hit the wall and a carbon fiber rod broke and pierced him through his visor.

 

I believe the whole front wheel/suspension broke and hit him in the head - this is why they now have tethers on them. He was going VERY fast and bottomed out - which is also why they limit the minimum ride height - at which time you lose air flow under the car and therefore the downforce and the car spun out of control. Had the suspension been steel or carbon it would have failed either way at those speeds. Look at the recent really bad Indy / IRL (dont remember which) wreck where the driver survived thanks to the very strong carbon cocpit. Like all materials composites have their limitations such as fracture toughness mentioned above but also can be much stronger, and especially stiffer than metals. It's kind of ironic in that a high end carbon fiber composite part should sound like metal if you tap on it.

 

Cameron

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quoted from designtech web page: This is why carbon is used in formula one chassis and aeroplane wings

 

And yet not in formula one wheels? I wonder why that is, they use it everywhere else (even the gearboxes, or so I hear).

 

I'm a bit leery of these as well. Plus I'm not overly fond of the look. I've seen a lot of carbon hoods turn yellow and peel from UV exposure here in Florida, and I don't think I'd like to have that happening on something as important as my wheels..

 

BJ, do you have pictures of those wheels on a car? those things are crazy looking.

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I believe the whole front wheel/suspension broke and hit him in the head - this is why they now have tethers on them. He was going VERY fast and bottomed out

 

Not to get too far off topic here, but I believe the current theory is his tires lost heat behind a safety car and more importantly ride height. When he came to the next high speed corner the car bottomed and he lost control.

 

I think the answer to why carbon wheels are not allowed in F1 has to do with rules. Last time I checked metal was required. I wouldn't use these on a street car of mine. Maybe a racer but I'd agree with the concern over bumps/potholes shattering them.

 

Cary

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