Weight & Torsional Stiffness for Space Frame Chassis ( Repost )

[zizorey8]

thanks everybody for making joke of me
I totally worth it
but it's our first year FSAE
now, let me ask clearly
How much should be the values of both weight and torsional stiffness for a space frame chassis
thanks in advance

[MileyCyrus]

You still haven't specified which type of cheese you are using, as previously discussed this will have a large effect on the results..

[Will M]

Zizorey8,

The problem is your question has no real answer.
Even knowing one we couldn't answer the other.

If you can come back with goals for chassis weight and stiffness,
(or better yet testing results),
along with WHY you have these specific goals then people here would be more willing to help you.

To summarize "Our responses are limited. You must ask the right questions."

-William

[ed_pratt]

Ok, at the expense of being labeled a spoilsport!...


Zizorey, Will is absolutely correct with that response. You need to come up with some values yourself and some ideas about why those values may or may not be realistic.
If it helps, try thinking of the spaceframe as a torsional spring.
How stiff will your suspension be?
How stiff do you think the chassis needs to be to allow the suspension to work effectively?

There are quite a few resources listed in the BOOK LIST stickied thread. Any of the Carroll Smith books will help. Have you tried looking at any of Pat Clarke's articles on Formula Student Germany?

Ed

[Frank]

I think we should move away from cheese and discuss red wine.

[Will M]

I'm not sure about red wine but i have heard good things about champagne as a fuel.

-William

[jlangholzj]

Originally posted by Will M:
I'm not sure about red wine but i have heard good things about champagne as a fuel.

-William

I'm wonder how much tuning I'd have to do to switch from e85 to cron mash whiskey??


in all seriousness, ex's point in the other thread really did get me thinking. What is "stiff enough"? Basically it comes down to an engineering decision. I mean there are ballpark values in some books but, how stiff is too stiff? is gaining an additional 10 lbs worth having a wet noodle for a frame? Who says that it's even a wet noodle....Its just another iteration of the whole FSAE/FS project as a whole.

[Warpspeed]

Overweight is bad.
Flaccid is even worse.
Too much cheese and wine can do it to you.

If doing this for the very first time, start out by studying the designs of other teams to get some initial ideas.
That is what sets the the current bench mark.
Try to figure out ways to do it better(if you can).

[Will M]

@jlangholzj

JerseyTom had a post on his blog about this a while back.
http://fsae1000.blogspot.com/2...-frame-rigidity.html

The images are broken but the rest is there.

-William

[Dunk Mckay]

This year we ste a target weight and maximised stiffness to that limit. We could have gone the other way. Or we could have set both and risked not meeting both targets, or worse settling for less than we could have gained.

At least give us an idea of what sort of car you're planning on building (engine type, wheel size, suspension setup, chassis type, etc.) then you might be in with a chance of getting an useful answer, even if we still don't givde you exact numbers, because their aren't any, it all depends on your goals.

If you just want to finish all dynamic events then just build a tank that meets the rules, don't worry too much about speed or performance, focus on completion time and reliability. Work on improving next year when you have learned how to work out your own targets.