kaizokuace
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| posted on 20/11/05 at 02:21 PM |
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chassis design questions
Hi, i am new to this forum. I am wondering if an aluminum chassis would work? is it not strong enough and higher gauge tubing? also would filling
the tubing with something like expanding foam add to rigidity?
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Messenjah
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| posted on 20/11/05 at 02:51 PM |
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if you use alu you have to make it thicker walled and add some more triangulation so you probably wotn save on weight at all
also i wouldnt like yo use an alu roll bar and where you join alu to steel will be weaker and they will react .....
just what ive read on this forum int he past and my views on rollcage
im sure someone else is much more knowledgeable then me and i stand to be corrected
try doign a search
aluminium chassis
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Kowalski
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| posted on 20/11/05 at 03:11 PM |
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Alumininium is stronger than steel per unit mass so in theory you'll need less mass of aluminium to make a chassis than you would steel so it
can work out lighter. Aluminium isn't as strong as steel per unit volume so you'd be using thicker walled tube to get the same strength,
but as I've already said it will be lighter.
An aluminium tube can be equivilent to a steel tube in terms of strength but will be lighter, it won't as stated above need any more
triangulation if you're using equivilient strength tubing.
The downsides to alu tube are that its more expensive to buy and much more diffilcult to join (you need a tig welder that will do alu, the cheaper
ones don't and even the cheapest tig welders are more expensive than a good mig welder).
You can get a lighter chassis with alu but its certainly beyond my ability to, if you've got experience of designing and building in alu you
stand a good chance of getting a good result otherwise I'd stick to steel, easier and cheaper.
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britishtrident
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| posted on 20/11/05 at 03:42 PM |
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Even if you go up in thickness and diametre you would hit problems many connected with the fatigue life of the joints.
An efficient alloy chassis is do-able but it would look nothing like like the book design. Do a Google search on on Lotus 25 (aka Lotus 33) and
compare it with the Lotus 24 or Lotus 18
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Avoneer
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| posted on 20/11/05 at 03:45 PM |
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Stress fractures???
Isn't that one of the big downsides?
Nothing wrong with a steel chassis.
Pat...
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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MikeR
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| posted on 20/11/05 at 03:49 PM |
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don't want to seem rude but do a search. This topic has been covered a 100 times (usually every 3 to 4 months).
Basically Ali can be used if you know the properties of the material and design around them. 'Our' space frame is designed around the
properties of steel.
Ali's major weekness is the fact that it has no elasic limit. As soon as you start using it fatigue is setting in. In airplanes etc this is
known and designed around.
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Mr G
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| posted on 20/11/05 at 07:39 PM |
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How Rude! 
Normal is getting dressed in clothes that you buy for work and driving through traffic in a
car that you are still paying for - in order to get to the job you need to pay for the clothes
and the car, and the house you leave vacant all day so you can afford to live in it.
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kaizokuace
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| posted on 20/11/05 at 10:10 PM |
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thanks guys, i'll not do aluminum then. The price is the main killer on me. My neighbor has a nice welding equpment that i use so welding
aluminum is not a problem. Just the design around the properties of aluminum structurally is currently beyond my knowledge. But i am just trying to
think of what to do to make it lighter. i am looking into doing all body shell parts in CF, i dont know how much lighter that is than the standard
body parts you guys use on the locosts.
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Stephant
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| posted on 22/11/05 at 11:41 AM |
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ally frame
Hi
This seems to be discussed many times.
To me, the question would be:why?
The chassis wights about 8-10% of the whole car.A perpectly designet ally frame could save up to 30% in weight(max),but would have to be a monocoque
instead of a space frame.
It means' redesign the whole car for loosing weight of about 2-3% .A ligtweight motor could save up to 40kg(Zetec SE - Pinto)
Best regards,Stephan
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Avoneer
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| posted on 22/11/05 at 01:56 PM |
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Whats the obsession with making it lighter?
What engine etc. are you planning on fitting that will need you to make the car lighter?
Pat...
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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Stephant
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| posted on 22/11/05 at 05:59 PM |
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why lighter?
Hi
I don't understand the question.You're building a bike powered 7 type car with less then half the weight of a production car,so you surely
know why.
My motor is a Honda CRX 16V Motor.Anyone who's driven such car must love the idea
of having that Motor in a car with half the weight.
Regards,Stephan
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JoelP
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| posted on 22/11/05 at 06:33 PM |
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as you say, there isnt much weight to be saved in a chassis. However, saved weight can be added back in to make it stiffer, which is definately worth
having.
Why lighter overall though? Pat, im suprised at you!  The whole idea is a light car with a good motor. Both for acceleration and cornering 
Beware! Bourettes is binfectious.
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Avoneer
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| posted on 22/11/05 at 11:50 PM |
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Sorry, I didn't mean to upset anyone.
By lighter, I meant why lighter than the normal design and structure and material that everyone uses with little problems.
Is that a bit clearer?
Pat 
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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