Do carbon fiber chassis get lose rigidity?

[brutus]

Hi there.. I was wondering if the carbon fiber monocoques decay with use. I know CF is not subject to fatigue like aluminium, but from what i have seem, they do get retired sometimes mid-season, and i have heard people refer to them "getting old".

Do they lose torsional stiffness, with time/use? If so, what happens exactly. I heard delamination of the CF layers might be a problem.

Any insights?

[proteus]

Im no wise guy, but i say yes. Trough time resin probably ages and cracks, especially unprotected places which are exposed to UV radiation. The resins are indeed very durable and they have a lot of aditives which are there to help protecting physicall durability and stability (used as well in protective paints) , but everything ages trough time. u can see that older F1 chasis have signs of aging, especially where the plates of CF are glued together, those joints are the most volnureable. So CF itself is not problematic, only the resin is.

[brutus]

Yes, i know the fiber itself lasts pretty much forever, but the resin seems to decay with time, UV exposure, etc.

Also, apparently Boeing had some crack problem with the 787 Dreamliner CF wings, but i'm not sure what the problem was exactly.

[Seattle]

So reading between the lines here, is this the theory why Lewis's car supposedly changed on him?

[Skippon]

Nah,

Nico Rosberg won at Abu Dhabi in chassis 1 - so he used the same chassis all season race and testing!!

[Seattle]

Nah,

Nico Rosberg won at Abu Dhabi in chassis 1 - so he used the same chassis all season race and testing!!

I agree, no, but I suspect this is why brutus has brought this up. Cuz how else could Nico be faster than the amazing Lewis Hamilton!?! It must be the car right?

As I recall, they did replace his chassis in 2013 for having a crack in it, no? But there are no fools at Mercedes. I'm sure they ruled something like that out before anyone online ever thought of it.

[BanMeToo]

Mate what the hell are you ranting about. Take it to another thread. OP said nothing about Mercedes or old boy Hami.

[Jolle]

Nah,

Nico Rosberg won at Abu Dhabi in chassis 1 - so he used the same chassis all season race and testing!!

I agree, no, but I suspect this is why brutus has brought this up. Cuz how else could Nico be faster than the amazing Lewis Hamilton!?! It must be the car right?

As I recall, they did replace his chassis in 2013 for having a crack in it, no? But there are no fools at Mercedes. I'm sure they ruled something like that out before anyone online ever thought of it.

Bit offtopic, but if Mercedes has one weak point, it's reliability in, for most teams, obvious bulletproof, erea's. I believe Hamilton drove several GP's with a cracked chassis before they found the flaw in 2013.

But a bit more ontopic, the big teams make a chassis for a smaller number of GP's, so they can be lighter before they have reduced stiffness because of fractures or delimitation what will happen eventually) then the smaller teams who will build usually just four (two race, one testing/spare and a crash test chassis).

So the question should be, does a chassis loose it's rigidity during it's calculated lifespan. Yes it does, because of vibrations hairline cracks will occur but the big teams change the chassis before it's noticeable.

[flynfrog]

This is not a driver thread. Please do not make it one.

[brutus]

I wasn't alluding to HAM vs ROS, or any other battle. It's really an engineering question.

In F1 most things are not durable, they only had to last at least one race, at most one season. Carbon fiber, however, seems to maintain its characteristics even after heavy usage, I'm just wondering if that's really the case.

Last season Vettel wasn't happy with his car, Red Bull inspected his chassis for cracks, and found none. So apparently CF can develop micro cracks that aren't obvious and do not cause catastrophic failure, but could hurt performance nonetheless.

I also wonder how could McLaren "fix" Rowan Atkinson's F1 after a severe crash. Did they really fix it, or did they replaced the entire CF tub?

[brutus]

But a bit more ontopic, the big teams make a chassis for a smaller number of GP's, so they can be lighter before they have reduced stiffness because of fractures or delimitation what will happen eventually) then the smaller teams who will build usually just four (two race, one testing/spare and a crash test chassis).

So the question should be, does a chassis loose it's rigidity during it's calculated lifespan. Yes it does, because of vibrations hairline cracks will occur but the big teams change the chassis before it's noticeable.

That's what i was asking. But does the same cracks/delamination happen in road going CF supercars?

[Jolle]

But a bit more ontopic, the big teams make a chassis for a smaller number of GP's, so they can be lighter before they have reduced stiffness because of fractures or delimitation what will happen eventually) then the smaller teams who will build usually just four (two race, one testing/spare and a crash test chassis).

So the question should be, does a chassis loose it's rigidity during it's calculated lifespan. Yes it does, because of vibrations hairline cracks will occur but the big teams change the chassis before it's noticeable.

That's what i was asking. But does the same cracks/delamination happen in road going CF supercars?

I would presume that for road cars the tolerances are not as narrow as in F1 plus the vibration is a lot less and different, so different stress levels. I would also presume that in road cars they use a resin that is a bit more flexible then in F1 cars, to prevent the buildup of hairline fractures. But everything vibrating had a limited life span...

As for Mr Beans F1, I have no idea how badly the tub was damaged. They could have replaced. In F1 every few GP's they recondishing the tub, reassessing all the pickup points for the engine and wheels/etc. So a CF tub is repayable.

[riff_raff]

If a composite laminate is subjected to sufficient levels of stress to produce local shear failure or delamination, then the failure will likely continue to propagate thru the structure at lower stress levels. Structural failure of the laminate will become a problem long before there is a noticeable loss of structural stiffness.

Detecting small local delaminations in complex composite structures is not an easy thing to do. Much easier, reliable and cost effective to simply replace the composite tubs on a regular basis.

[ChrisF1]

I seem to remember suggestions that the IndyCar chassis from pre-2012 were very old physically, not just in terms of when the design was penned, and this was a contributing factor to injuries sustained. I think it was mentioned at around the time Dan Wheldon was killed.

Sure i've heard about tubs being bonded together in places because they were weakening. Wish I knew where that was.

Edit: Wow, just changed the above from 2014 to 2012. Cannot believe Dans been gone for over 4 years.

[riff_raff]

I seem to remember suggestions that the IndyCar chassis from pre-2012 were very old physically, not just in terms of when the design was penned, and this was a contributing factor to injuries sustained. I think it was mentioned at around the time Dan Wheldon was killed.

Sure i've heard about tubs being bonded together in places because they were weakening. Wish I knew where that was.

Edit: Wow, just changed the above from 2014 to 2012. Cannot believe Dans been gone for over 4 years.

Champ car chassis are purchased by each team from a supplier, while F1 teams produce their own. Champ cars are heavier than F1 cars. But Champ cars also must be capable of handling impacts at higher speeds due to racing on speedways. Champ car teams don't have the financial resources that F1 teams have, so naturally they tend to run their chassis for longer.

However, even back in 2012, I'm pretty sure the composite tubs used in Indy car were single piece. Many years ago some composite tubs were two-piece (upper and lower halves) and adhesively bonded along a horizontal lap joint.