How does carbon fai...
 

[Closed] How does carbon fail?

 wors
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Slow propagating cracks or one big let go?


 
Posted : 22/02/2011 10:33 pm
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It turns to dust and blows away.


 
Posted : 22/02/2011 10:35 pm
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depends.


 
Posted : 22/02/2011 10:36 pm
 LHS
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Big open ended question there.

You need to define constraints and loading conditions.

Shape factor? Hollow tube?


 
Posted : 22/02/2011 10:37 pm
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A few answers at http://www.bustedcarbon.com/ (seriously!).

Well, maybe not answers, but pictures and stories anyway.


 
Posted : 22/02/2011 10:39 pm
 wors
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My carbon forks on my road bike. Brake caliper nut rounded so had to cut it off and knock it out with a hammer. Just concerned i might have done some damage.


 
Posted : 22/02/2011 10:44 pm
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Usually, you'll pass a thorn bush and one of the thorns will snag the carbon weave. The carbon then slowly un-knits as you are riding along, until there's too little to hold the wheels apart and down you go.

On the up-side, if you can find your granny (or borrow one) and a set of knitting needles, she can put it back together for you.

I've heard that some riders carry knitting needles with them whilst out on the trails, but that's just unbelievable!


 
Posted : 22/02/2011 10:46 pm
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I thought it involved tiny barbed spears travelling slowly to your heart ?


 
Posted : 22/02/2011 10:46 pm
 ojom
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The dark matter in the resin is activated in crashes and causes a black hole to open and the frame goes through a wormhole thus disappearing.

Hth


 
Posted : 22/02/2011 10:49 pm
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wors - Member
My carbon forks on my road bike. Brake caliper nut rounded so had to cut it off and knock it out with a hammer. Just concerned i might have done some damage.
Were you hitting them any harder than this??


 
Posted : 22/02/2011 10:52 pm
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that vid's great and all that but I'd like to see the fork stressed afterwards - obviously there'll be no catastrophic failure until then

why not shove it on a testing rig & load it a few times ?


 
Posted : 22/02/2011 10:56 pm
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"How does carbon fail?"

How long have you got?

Short version:

1st failure will be the resin and you will get delamination.

2nd failure is more extreme and is the fibres breaking.

How much damage have you done? Maybe none, maybe some. If some will it spread? eventually but at what rate is unknown and it can still be very strong.

Carbon fibre can take a hell of a lot of abuse and can tolerate a lot of damage. Hammering was probably a bad idea but you will probably be fine. It can actually behave a lot differently at high speed and recover with no damage when a metal part would be bent and need heat treatment before bending back.


 
Posted : 22/02/2011 11:04 pm