Torsional Stiffness of Body 1

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Hello All,

I am working on designing a frame (Roll-cage) for BAJA SAE. I am wondering if there is any thumb-rule for torsional stiffness of the roll-cage?

I mean if there is any thumb-rule relating the roll stiffness of suspension and torsinal stiffness of roll-cage.

regards

 

[GregLocock]

For many years successful single seat cars at the highest level had a stiffness of around 1500 lb ft/degree

Good 2 seater production cars during the 80s might have been 4000 lb ft/degree.

There seem to be some handling benefits in increasing it to 10000 lb ft/degree, but I suspect 6000 is a sweet spot.

However this has to be offset against increased weight and cg height, both of which have far more direct bearing on handling than torsional stiffness.



Cheers

Greg Locock


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Greg

Thanks a lot!

 

[JayMaechtlen]

It's great to have some target numbers.
- does a particular stiffness value mean the same for a FSAE versus a Miata-sized vehicle versus a larger vehicle?

or, maybe I should ask "what does the different body size imply, if using the same target stiffness?"



Jay Maechtlen

http://www.laserpubs.com/techcomm

 

[GregLocock]

That rather depends on why you think you are doing it. There is a squeak and rattle/secondary ride benefit in increasing the first torsional mode of the body somewhat, in which case you'd want a stiffer body for a heavier car.

On the other hand I know that a 4000 lb ft/deg sportscar can run out of shock absorber-reacting stiffness, so you might argue that cars with beefier shock calibrations need stiffer bodies.





Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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