jcduroc
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| posted on 21/6/04 at 11:15 PM |
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quote:
Originally posted by britishtrident
For torsion test/FEM a good estimate of suspension loads can be found by considering a 1.2 g cornering load -- find the lateral weight tansfer,
then the corner weights when front roll stifness is high enough that enough that the front inside wheel is lifted clear of the ground...
In fact nobody has published the figures he used his analysis: how many kgs in the 2 engine and gearbox mountings, suspension mountings and seats
mountings.
Were only static figures used? Was 1.2g cornering considered? Lifting the inside wheel (ie, all the front axle weight on the outside wheel)?
And what about braking at, say, 1g before the bend, then cornering at 1.2g and (suddenly, in the middle of the bend) going over a road bump 50mm
high?
Wouldn't it be interesting to consider and publish the actual figures?
Just a thought
Joćo
JCM
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pbura
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| posted on 22/6/04 at 02:14 AM |
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quote:
Originally posted by jcduroc
Were only static figures used?
Yeah, a beaming test (or a simulation thereof) where the rear end of the chassis would be clamped down and twist applied to the front end with a
lever.
2X or 3X the car weight applied to the front end causing a deflection of only 1 degree impresses me. Could there be that much force applied to a
corner in a driving situation?
Pete
Pete
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crbrlfrost
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| posted on 22/6/04 at 03:04 AM |
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Not without serious wings, very sticky tires and probably venturi sections; along withon the edge braking and corning. Then it may be possible, but I
wouldn't try that hard. Cheers!
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TheGecko
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| posted on 22/6/04 at 03:45 AM |
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quote:
Originally posted by pbura
Yeah, a beaming test (or a simulation thereof) where the rear end of the chassis would be clamped down and twist applied to the front end with a
lever.
Just a slight clarification - the test you describe is a torsion test. The beaming test consists of fixing the chassis through the suspension
mounts, applying a load (something like 200kg+ per seat) through the seating positions, and measuring the deflection (or lack thereof).
quote:
2X or 3X the car weight applied to the front end causing a deflection of only 1 degree impresses me. Could there be that much force applied to
a corner in a driving situation?
One of my reference books (Forbes Aird?) says that peak loads often occur in a "curbing" event
i.e hitting a, say, 50mm/2" high curb during a corner. This can easily result in transient loads of 3G+. Don't quote me on that number -
I'm at work and don't have the book handy.
Dominic
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britishtrident
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| posted on 22/6/04 at 06:19 AM |
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I pulled the 1.2 g figure out of a hat as ballpark max transient figure that could be expected with decent performance road tyres under transient
conditions with say 0.9 g as a sustained lateral acceleration. Thinking about it the real situation to consider is an S bend 1.2g to - 1.2g, so
2.4 g would be more realistic .
How the frame is restrained will have a big effect on resultds from an FEM model or a workshop torsion test
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