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PostPosted: June 23, 2007, 7:09 pm 
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Finite Element Analysis (FEA) software enabled chassis stiffness to be optimised.


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To gain a ‘tortional stiffness’ figure, Caged reverse-engineered the original chassis into SolidWorks and used Cosmos to obtain this figure. The company then optimised the chassis tubes to increase stiffness using a set of parameters that they felt would work. “When we then installed a range of engines that we needed to package and checked the chassis we had a clash – so we changed the tubes to suit, ran the chassis through Cosmos again and gained the additional increase.”

Following the introduction of the state of the art chassis construction techniques the result was a 14 per cent increase in torsional rigidity. After the clash was discovered with the engine mounting and a problem of space for the alternator was resolved by use of SolidWorks, rigidity was increased by another 0.5 per cent again.

as found here.....
http://www.autoindustry.co.uk/articles/09-08-06

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It would be interesting to know the torsional stiffness of the Catherham frame.
as found here....
http://www.therollcagepeople.com/gallerycaterham.htm

They also make the Stuart Taylor Chassis...

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Last edited by mr.peabody.d on June 24, 2007, 12:53 pm, edited 1 time in total.

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PostPosted: June 24, 2007, 12:10 am 
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Intersting pics. That Caterham frame looks to be brazed instead of welded. I remember hearing that they did this back in the day, I'm suprised they still do it. I guess less heat=less chassis distortion?

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PostPosted: June 24, 2007, 1:02 pm 
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The robot will weld using the ‘SP MAG’ system. Imagine this as MIG welding – but on steroids, with no undercut and with a repeatable accuracy of 0.1mm! The computer collects welding data every 100 micro seconds and monitors for welding defects and corrects current, voltage and wire speed automatically depending on the material type and thickness it encounters. The robot will also pulse weld 100 times per second minimising the heat input into the chassis and therefore reducing the heat effected zone. Another welding option is the DIP PULSE system that lets us weld thick and thin material together, ideal for items such as the dedion tubes.


Sounds like they got some crazy robot TIG Thingy.....

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PostPosted: June 24, 2007, 4:31 pm 
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The Tiganator.


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PostPosted: June 25, 2007, 2:19 am 
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:drool: :drool: :hail:


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PostPosted: June 25, 2007, 12:17 pm 
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I've never seen a TIG weld brass/bronze before. Those pics don't look like any TIG welding I've ever seen before.

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PostPosted: June 25, 2007, 4:09 pm 
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Until VERY recently all Caterham frames were Brazed by Arch Motors. (Who also do At-om frames.)

I know the new Cats are to be welded,though I am not sure whether that will be only new models or all of them, or a gradual phase out, etc.

T


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PostPosted: June 25, 2007, 6:46 pm 
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Tralfaz wrote:
Until VERY recently all Caterham frames were Brazed by Arch Motors. (Who also do At-om frames.)

I know the new Cats are to be welded,though I am not sure whether that will be only new models or all of them, or a gradual phase out, etc.

T


Well that certainly explains things. Thanks! [/hijack]

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PostPosted: June 28, 2007, 10:50 pm 
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My new chassis will be in the 9000 ft-lbs / degree range and I can easily get in and out. It does take a real cage but it can be done. Get the mind set that if its not a triangle its almost worthless and think out of the box. FEA is easy to learn and I have posted links to everything you need to rock and roll.

Hint the roll cage is the first thing you build that everything else mounts to. The rollbar is NOT the last thing that goes on added to the top of the chassis.

AW


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PostPosted: June 28, 2007, 10:59 pm 
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whittlebeast wrote:
My new chassis will be in the 9000 ft-lbs / degree range and I can easily get in and out. It does take a real cage but it can be done. Get the mind set that if its not a triangle its almost worthless and think out of the box. FEA is easy to learn and I have posted links to everything you need to rock and roll.

Hint the roll cage is the first thing you build that everything else mounts to. The rollbar is NOT the last thing that goes on added to the top of the chassis.

AW


Wow, look who's back. I thought you traded locostering for motorbiking. :) Glad to see you're still at it.

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PostPosted: June 29, 2007, 12:05 am 
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Wow, 9000 foot pounds per degree! I'll tell ya, there are Locosts out there at less than 1000 ft-lb/degree, 9000 is quite a jump. How heavy do you expect the chassis will be? (oh yea, and what Chetco said--welcome back, we've missed you).

On a related subject...
rust_bucket wrote:
I doubt anyone wants to spend 3 weeks+ building a chassis just to have Jack torque it in half because something went wrong and then turn around and add one or two more tubes and torque it again.

...my experience with steel frames (which is somewhat limited) is that those that aren't strong enough aren't stiff enough either. If there's a stiffness problem it will most likely show up well before anything on the chassis yields, and almost surely before anything breaks. But if my test equipment <does> torque your chassis in half, wouldn't you rather know it in the shop than on the street?

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PostPosted: June 29, 2007, 6:55 am 
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It just depends if you want it to handle. I just keep adding tubes till there is no bay that falls apart when twisted then I start deleting all the black ones. EZ :) When your done the FEA lights up on your screen like a Christmas tree.

Over the years I wasted 10s of thousands of dollers on shocks and sway bars. Nothing worked the way the books claimed things should work. I figuring out that it was the shock pickup points moving up and down and the shocks were not going in and out. The next year I designed a new chassis and all the books were correct.

Here is a FSAE chassis I did years ago just to prove to the SAE guys it could be done.

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PostPosted: June 29, 2007, 10:37 am 
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whittlebeast wrote:
It just depends if you want it to handle. I just keep adding tubes till there is no bay that falls apart when twisted then I start deleting all the black ones. EZ :) When your done the FEA lights up on your screen like a Christmas tree.


You make it sound EZ, all right. Tell me what FEA program does that easy stuff, and maybe I'll become a convert yet.

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PostPosted: June 29, 2007, 10:42 am 
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http://www.grapesoftware.mb.ca/dloadv4.html

once that is up and running PM me and I can give you the rest of the story

You will need to get a few files from

www.ncs-stl.com/Files/Fea

AW


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PostPosted: July 1, 2007, 10:28 pm 
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The thing I don't fully understand about FEA is how to convert the amount of displacement into ft-lbs/degree of twist.

I tried to use GRAPE and I could never get it to operate right for me.


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