Torsional rigidity values of chassis

[eddyweaner]

Can anyone help i am looking for values for the torsional rigidity values of other teams chassis to write a report critacising ours. Any info or links would be greatly appreciated. cheers

[eddyweaner]

Can anyone help i am looking for values for the torsional rigidity values of other teams chassis to write a report critacising ours. Any info or links would be greatly appreciated. cheers

[David Money]

We were told by a design judge from Ricardo that we should strive for 1200 lbs per degree. I was reading on the University of Missouri Rolla site last night that they strived for 2200 lbs per degree. That can be seen here http://web.umr.edu/~formula/library/...per/paper.html

Thanks.
David Money

[eddyweaner]

That was a great help, thank you.

[EliseS2]

Our frame is around 1700 lbs/degree. This is probably too stiff and our next frame we will aim for a 1400 lbs/ degree and shave off at least 20 lbs off the front frame.

[Erik C]

1700 ft*lbs/deg could be too stiff, or not stiff enough. It depends on what your roll stiffness distribution is, among other factors. And saving 20 lbs for a reduction in stiffness of 300 ft*lbs/deg sound a little extreme. 20 lbs is 55 ft of .035 tubing or 30 ft of .065 tubing!!! If you can save that much weight on just the front frame, imagine how much more weight you guys can shave off.

[David Lemire]

Hello Everybody... we have already heard about different way to find the torsional stiffness but I still don't know how to implement all that in a FEA software... we would like to know the best (and a kind of standard) way to figure this out...

Is there any way to get this torsional stiffness value directly from the FEA software...

Any help please

David Lemire
Team Leader
McGill Racing Team

[Travis R]

Our 2002 frame tested at 2450 ft-lbs/deg. We too are probably going to sacrifice some of that stiffness for weight gain for 2003. But we only weighed in at 475 lbs. (wet) at competition. [img]/infopop/emoticons/icon_cool.gif[/img]

Travis Rouse - Test Pilot - The University of Texas (Austin)

[Jeff Curtis]

The stiffness numbers you ar giving mean a pile of beans. The real key is how you test for your stiffness. Is it loaded through the suspension points. 90% of the game when it comes to chassis stiffness is having good suspension load paths.

1. In my opinion most cars are not as stiff as they say they are. Because of poor testing procedures.

2. Most cars at the competition have too soft of frames and probally don't relize it.

Jeff

[Erik C]

I agree that having a frame which is not "rigid" will cause difficulty in the tuning of the chassis. However, at which point do you say that it is stiff enough? I am sure we could all build cars with an insane amount of torsional stiffness, but what for? When the car is driving, where do the torsional loads come from? For a car that is designed to run with an equal F/R roll distribution, having a chassis that weighs 100lbs but has a torsional stiffness of 3100 ft*lbs/deg doesn't make much sense. When you could have a much lower weight and torsional stiffness which will suffice for your car.
Anyway, just my .02.