merkurman
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| posted on 23/3/04 at 02:53 PM |
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looking for monocoupe info
on my formula student team we are looking into doing a alloy monocoupoe chassis next year and are looking for some good websites and books on the
topic. so if anyone knows of any they can fire away.
nick
1962 fairlane with a 200" six and T5 5spd, shaved trim air ride, t3/t4 turbo and soon to be EFI
-- looking to put a offy tripower intake on soon
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Peteff
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| posted on 23/3/04 at 03:10 PM |
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Monocoque chassis?
I've read about a few projects but they are mostly for ultra lightweight machines to achieve high mpg figures with low profile bodywork and
skinny tyres to reduce rolling resistance. Most cars nowadays use monocoques as they are cheaper to produce using the whole body as a stressed member
and fixing everything directly to it or just bolting subframes on with the mechanical bits attached to them
http://www.opencortex.org/index.php
There is a 7 type car that uses similar construction but the builders don't show any plans.
http://www.prbaustralia.com.au/PRBcomposite.htm
[Edited on 23/3/04 by Peteff]
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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ned
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| posted on 23/3/04 at 03:12 PM |
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sports 2000 cars use monocoques, lola's and the like. pressed ally panels bent and formed and rivetted together, with subframes for front and
rear suspension, though i'm sure you already know that - DOH!
Ned
beware, I've got yellow skin
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stressy
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| posted on 23/3/04 at 04:32 PM |
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Hi Nick, if you dont get bored too easily, read on!
Pesumably if you already have an Fs car at uni you have the design conditions you will be working to, i.e. critical inertias under accelerating,
braking and corners etc and i guess you have a target for the torsional stiffness you require.
The chassis function is the same as any other the only difference really is how to design the structure.
fundementally to design a monocoque car start with considering it as simple flat rectangular panels orientated to form the basic "box"
shape you require.
In a spaceframe construction members should only carry axial loads (and an element of torsion), hence not applying suspension loads away from tube
junctions, a monocoque must be designed equivelently to carry inplane shears and axial load not bending in each of the panels as far as possible. A
useful point, to achieve minimum out of plane loading in your sytructure mount suspension etc. in coincidence with the inner bulkheads( i.e back of
the seat, dash,knees and pedals. )
Analytically the design is akin to any other "thin wall structural design" processes, the best books will be in the Aerospace section of
your library(maybe also try civil engineering).
construct a simple free-body force diagram and evaluate magnitude and directions of loading for each of the panels for, bump, torsion, etc.. for a
state of equiliprium.
from the loads calculated on each panel and the materials avaliable for the skins you can then calculate the thickness required in each case fo
strength and estimate the deflected stiffness(simple fe model is god for the latter if it is avaliable)
You will find you need suprisingly little material to carry the loads a light car can produce. (fundemental strength of materials book look at
prinipal stress and von mises etc.)
Having defined a simple strength driven structure you will then need to look at stability, anywhere you have shear or compression this may be an
issue. this is why you will find most modern cars will use sandwich panels, split the required total thickness for strength in 2 mount the skins on an
aluminium honeycombe core for example and they will become stabalised. (design of flight vehicles by Bruhn has a good chapter on these topics)
My advice for reading would be as follows:
if you search for HEXCEL you will find they supply these sorts of materials preformed as sheet and they used have reccommended methods of joining and
forming etc on the site.
look at structures books, aireospace structures for students txt is a good starter, i remember one by megson? being quite good.
Look at composites books specifically with regards to potted inserts.
Look at Ciba Gigi probably spelt wrong) for boding materials.
If your not asleep yet then Hope my ramblings may be of some help. Apologies for quality of english i cant type quick and make sense at the same
time!
Cheers C
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merkurman
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| posted on 24/3/04 at 03:24 AM |
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gonna look into the avaition books as we have a huge avaition maintance program here (they do our composites work)
nick
1962 fairlane with a 200" six and T5 5spd, shaved trim air ride, t3/t4 turbo and soon to be EFI
-- looking to put a offy tripower intake on soon
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