Chassis Fatigue

[gcdugas]

What is the fatigue factor in an F1 chassis? Brawn have two drivers that don't crash and I think they still only have two chassis made. Ferrari, Mac, Renault and other teams often make as many as 5-6 chassis per season. Now we do have less testing so that figures in but I am wondering if a F1 chassis endures appreciable fatigue during the season. Things like torsional rigidity, torsional harmonics remaining constant, shock absorption and shock transfer.deadening properties remaining constant for 20,000 Km or so etc.

I know that it is a dirty little secret among golfers that carbon shafts age somewhat and their flex characteristics vary. I guess nothing in life is exempt from entropy so I ask about F1 main monocoques? The suspension parts are almost alway new, the gearboxes are replaced every four races, the motors are replaced regularly so all that remains "unrefreshed" is the main monocoque.

Has this been discussed? Might it be a reason why Button can't find the "sweet spot" any more? I know that in 2002 Schumi had a favorite chassis and one he wasn't fond of. Perhaps it is manufacturing consistency, perhaps it is mileage fatigue or temperature fatigue.

Any comments?

[Jersey Tom]

I can only speak for steel spaceframes, but generally since stiffness of a frame is the main design criteria, they are way overbuilt from a stress standpoint. Given that, fatigue isn't a huge concern other than routine crack checking.

Some materials do exhibit strain softening... not sure if the matrix in a CRFP is one of them.

[bhall]

Didn't Alonso use the same chassis for the entire season in '05 or '06?

[PlatinumZealot]

I know that Carbon fibre itself has extreme resistance to fatigue.. but the Other things like the different resins and glues that are used with it might not.

But still I have no idea how long it take a chassis becomes soft, if they do at all. Maybe they New chassis could have other design updates ans the old ones are put away even though still good?
Maybe they weren't even designed for infinite cycles in the first place???

[Carlos]

EARLY FATIGUE DAMAGE IN CARBON FIBER COMPOSITES
OBSERVED BY ELECTRICAL RESISTANCE MEASUREMENT
Introduction:
"Fatigue life determination requires attention near the end of the fatigue life.
However, understanding the fatigue process requires investigating the entire
evolution of fatigue damage. Due to extensive damage shortly before fatigue failure
the sensing of fatigue damage near the end of fatigue life is not difficult."

I think he decided to start out the paper with a light hearted, slightly ironic engineering joke.

http://www.mrs.org/s_mrs/bin.asp?CID=12 ... C=FILE.PDF
6 pages.

[spacepig]

It's not unusual for the core to start to delaminate from the outer skins, but this usually takes multiple seasons. There are 6 year old Dallaras running at the dull end of the IRL grid, although most of them have been replaced and are probably less than 3 years old. But those cars live a much harder life than an F1 car. The old Lola Indy Lights cars were pretty floppy by the end of their life, and they ran for 5 or 6 years I think.

I'm also pretty sure Brawn has made more than 2 tubs. I wouldn't be surprised if they tear the cars down halfway through the season and give them a torsion test to check that nothing has changed. Brawn had to do some chopping and gluing on the back half to fit the Mercedes, so they are probably more concerned about potential delamination than most teams.

[noname]

What is the fatigue factor in an F1 chassis? (...)

once designing the system you are looking on the life of the components and usually they are designed to spec (like i.e. gearbox - for the whole 4 races is enough, designing it to last 8 or 10 would not be wise. gears may be changed more frequently so the limits are lower).

also different materials behave differently and so are sized by different factors and failure modes. yield is an issue for metal but not for composite, which are brittle, for example. on the other hand composites are susceptible to delamination, foto-oxidation, some fluids (fuel, hydraulics...), do not like local forces, etc.

F1 cars are designed with in-build capability for development. my guess is that in case of chassis main "survival cell" is designed to last the whole season (you have new car every year so you do not need more) but the areas expected to be updated, or prone to damages (like suspension mounting points or other interfaces), can be more or less easily replaced. of course if team decides there are important benefits of having chassis lasting shorter so it be. the same can be true if they decide to bring update heavily influencing the chassis, to the point you need a new one.

[ESPImperium]

This is where this chart comes in to play for the 2009 season:


DIRECT LINK: http://img.photobucket.com/albums/v66/I ... isData.jpg

[axle]

This is where this chart comes in to play for the 2009 season

I read that Rubens had the new chassis not JB...

[gcdugas]

What does that chart mean? Each team usually has a few iterations of the same chassis (tub) in a season such as F60.01 F60.02 F60.03 etc. As axle pointed out RB has been running what is effectively BGP001.03 which is freshly made. I am wondering about the ability of a chassis to retain it full properties over the span of a season. Or does it suffer measurable degradation enough that it affects performance? Can your chart tell that? I don't think so.I know Alonso has raced at least three different iterations, meaning three different physical "tubs", of the R28 so far this year.

[Conceptual]

What does that chart mean? Each team usually has a few iterations of the same chassis (tub) in a season such as F60.01 F60.02 F60.03 etc. As axle pointed out RB has been running what is effectively BGP001.03 which is freshly made. I am wondering about the ability of a chassis to retain it full properties over the span of a season. Or does it suffer measurable degradation enough that it affects performance? Can your chart tell that? I don't think so.I know Alonso has raced at least three different iterations, meaning three different physical "tubs", of the R28 so far this year.

Chart says Nando only used 2 different tubs, unless Spa was different...

Why does the chart say that Jenson used KERS in Malaysia? That is news to me!

[Rob W]

According to that Chart above Nakajima and Rosberg swapped chassis at the European GP and then swapped back for Belgian. If so, why?

Maybe Nakajima queried the team over Roseberg's better performances being down to chassis variations so they swapped to check.

[Tiakumosan]

Acording to Williams site, they will produce 4 chassis this year.

http://www.williamsf1.com/car/facts-stats/

[ESPImperium]

Thanks for pointing out a couple of f-ups. I will rectify them immediatly.

Nakajimma and Rossberg never changed, sorry.
Button did not run Kers at MAL, that was a colour left over from an old Key Coding.
Rubens has the new Chassis at BEL, not Button.

[James_graham]

Teams check safety critical components using ultrasound scanning and various other NDT techniques, If there is no problem I am sure they will continue to use them instead of building new ones. Chassis are very expensive and take a long time to manufacture!