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SetchUK
11-12-2003, 05:14 AM
Hi, i am working on the suspesion mounts and chassis inserts for the University of Hertfordshire car for the UK comp in 04. Have any of you got any data on forces transmitted through the wishbones? cheers, Ian
SetchUK
11-12-2003, 05:14 AM
Hi, i am working on the suspesion mounts and chassis inserts for the University of Hertfordshire car for the UK comp in 04. Have any of you got any data on forces transmitted through the wishbones? cheers, Ian
Denny Trimble
11-12-2003, 06:24 AM
How about using the max tension/buckling strength of your control arms, and designing your hardpoints to fail after the control arms do?

University of Washington Formula SAE ('98, '99, '03, '04)
Angry Joe
11-12-2003, 09:05 AM
Your design should be limited by stiffness, not failure...



Lehigh Formula SAE Alumni
Team Captain 2002-2003

www.lehigh.edu/~insae/formula (http://www.lehigh.edu/~insae/formula)
MercerFSAE C. Burch
11-12-2003, 09:42 AM
Well, what maximum forces do we see in our control arms? At the front I've calculated a max of about 5200 lbf in one of the lower arms and about 3300 lbf in the top arms and the pull rod. I haven't calculated the rear yet.

-Chris
Denny Trimble
11-12-2003, 11:42 AM
If your brackets are contributing to deflections, you've got a problem in your design. Generally they are small enough that displacements are also small. Longer members like A-arms, and members in bending like uprights and spindles, tend to be where most of the deflection comes from.

Chris, your numbers seem about 10X higher than our recent calculations. What size tubing and rodends are you using? We've used 5/8 x .035 all around in the past, we're thinking of moving up one or two sizes this year for stiffness.

University of Washington Formula SAE ('98, '99, '03, '04)
SetchUK
11-13-2003, 03:34 AM
cheers for the info http://fsae.com/groupee_common/emoticons/icon_smile.gif
MercerFSAE C. Burch
11-13-2003, 04:41 AM
That's not the stress in the arm, just the force imposed in a 2g braking and cornering, 4g bump situation. My chassis pickups for the a-arms are spaced 10" apart right now, and possibly that is not enough to reduce the forces present. We haven't looked at what size arm to use yet.

-Chris