Nitrogeno25
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| posted on 7/9/05 at 03:25 AM |
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Rear triangulation and brackets
I went the IRS route (not very convinced at last). I added I think to much triangulation compared to a Westfiled or MK chassis with IRS I think the
front demands better triangulation as acceleration forces should be lower than bracking forces. The same applies for the wishbones brackets (with more
load at the front)
What do you think?
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cymtriks
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| posted on 9/9/05 at 07:46 PM |
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triangulation
Yes, the front does benefit from a few extra tubes but the book chassis is so poorly triangulated to start with that it's easily beaten by a
simple X braced ladder frame.
Search for finite element analysis, mostly under my login name, or look at kitcaranalysisV2.doc on http://locost7.info/ in the files section under
chassis.
You will always improve a spaceframe by putting a diagonal across a rectangular hole in the framework so don't worry about overdoing it!
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Nitrogeno25
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| posted on 9/9/05 at 07:54 PM |
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Thank you very much! I already read it (many times  ) and made some of this modifications to my chassis
quote:
Originally posted by cymtriks
Yes, the front does benefit from a few extra tubes but the book chassis is so poorly triangulated to start with that it's easily beaten by a
simple X braced ladder frame.
Search for finite element analysis, mostly under my login name, or look at kitcaranalysisV2.doc on http://locost7.info/ in the files section under
chassis.
You will always improve a spaceframe by putting a diagonal across a rectangular hole in the framework so don't worry about overdoing it!
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Liam
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| posted on 10/9/05 at 01:03 AM |
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If you think you've over engineered your rear suspension area, have a look in my photo archive! I've nothing at all against the quality
and suitability of something like a westfield or MK chassis, but you have to appreciate that they are designed with a strong bias towards ease and
speed of manufacture. On a self build it's no problem to spend weeks adding tiny little extra tubes all over the place!
IMHO the stiffness of the rear suspension/diff box is just as important as any other part of the chassis. Certianly with mine because my shock loads
go into the box (which is why mine is made really strong), but even in a normal design where the shock loads go to the top corners of the rear
bulkhead. I remember that article (university thesis?) on the development of the Luego Viento chassis - it totally ignored the rear diff box in the
model as it makes no difference to the FEA modelled torsional rigidity of the chassis when you 'hold' it at the rear shock mounts and
twist it. But hello, the wishbones still attach to the diff box and any lateral loads are transfered into it, so it's stiffness is still of
major importance to the handling characteristics of the car! Just an example of armchair engineering failing to apply fully to the real world...
Liam
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cymtriks
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| posted on 10/9/05 at 11:16 AM |
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quote:
Originally posted by LiamI remember that article (university thesis?) on the development of the Luego Viento chassis - it totally
ignored the rear diff box in the model as it makes no difference to the FEA modelled torsional rigidity of the chassis when you 'hold' it
at the rear shock mounts and twist it. But hello, the wishbones still attach to the diff box and any lateral loads are transfered into it, so
it's stiffness is still of major importance to the handling characteristics of the car! Just an example of armchair engineering failing to
apply fully to the real world...
Liam
Bang on!
That analysis was done by students who, almost by definition, don't have a lot of real world engineering experience to draw on.
My analysis didn't deal with independent rear suspension as at the time everyone was going live axle or Deon.
The box around the dif should be triangulated for exactly the reasons you state.
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JoelP
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| posted on 10/9/05 at 05:51 PM |
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IRS acceleration still acts through the box as well.
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quattromike
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| posted on 24/9/05 at 04:41 PM |
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I'm just at this point of trianglation at the rear diff box and I feel because i'm building with stainless steel it'll have to be
extra stiff to save any twisting and torqueing and causing cracks.
Which isn't good ,
but I also don't wont to go over the top but where do you draw the line?
I'll get most of it done then post some pictures for some comments
Mike
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