Calculating roll bar stiffness / data?

[ben_uk1981]

Hello,

I am doing a motorsport project and wondered if anyone can help me with the data I have?

I have a setup sheet for a touring car and it only has the below values for the ARB's.

Is there any way you can calculate the n/m from these values, or are they pretty meaningless without more information?

90 degree blade
ARB
Front
40 X 3mm

90 degree blade
ARB
Rear
40 X 5mm

Thanks,

Ben.

Edited by ben_uk1981 on Wednesday 11th July 14:13

[LordGrover]

Here?

[luckystrike]

You’d need much more data, material being the obvious one but the mounting points and lengths will be needed to calculate the torsion across the beam, plus actual load vs displacement data.

If you have a full set of data for a specific bar you can then infer what would happen if one of the variables changed (for example if the current bar moves 5mm with loads applied then if it was made out of a material which was twice as stiff then you know it’s going to move about 2.5mm) but you need that baseline in the first place.

What’s the context?

Edit: if you’re assuming the materials are the same for both bars then the calculator posted above is a very useful tool.

[InitialDave]

Yeah, not enough data there for anything other than a rather woolly "assuming otherwise identical, the relative increase on stiffness would be X%".

Is this part of a question you've been set or something?

[tapkaJohnD]

According to Staniforth:

Q = 10^4 x T^2 x K^2 x d^4 / R^2 x L
where
Q = stiffness in lbs/in/degree
T = track
K = Lever arm ratio (movement @ pickup/movement of wheel)
d = bar O/diameter
R = Effective arm length (parallel to midline)
L = HALF length of actual bar

JOhn