Suspension Project

[Chubbs]

Hi

I have been given a project at uni and asked to design a suspension system for a racing car from scratch. Here is the data i have been given...

Chassis: Spaceframe
Chassis width: 480mm
Wheel Size 13 x 7
Tyres: 180/55
Static camber (degrees):2.5
Castor (degrees): 6.5
Damper actuation: Pull rod
Shock: Dual shock
Upright: CNC Aluminium
Camber Comp: 10%
Installation ratio 1:1
Roll bar: T Bar

What i want to know is... where would i start? whats the best way to go about this? and are there any articles that will be helpful? i have found a few but would like to see if anyone else knows any more.

Thanks!

[scarbs]

Trawling around the formula student websites should give you a good insight, the perennial 'competition suspension' by Allan Staniforth is as good a guide as ever there was.

[Chubbs]

thanks i got that book out n its helped a bit so far and looks like it will help a lot more but i cant find much on the formula student sites...

anyone else got any pointers?

[majicmeow]

A lot of your design is going to be affected/restricted by the car around it. That being said, I think its hard to give advice regarding geometry without seeing the rest of the chassis.

I only guess you are building a Formula SAE car, so in that case low COG is your friend. You'll also have to take into consideration things like the dampers/springs/materials/wheel offset/ that are going to be used.

Long control arms need to be backed by stronger dampers/springs/antisway bars to negate the extra leverage, unless you change the pull rod ratios (amongst other things). The opposite goes for a short armed suspension.

High/low offset wheels can also change the leverage, so choose accordingly.

If you are able to post pictures, it would go a long way towards providing a valid opinion of your situation

Best of luck on your project, I'm interested to see what you come up with!

[majicmeow]

Did a quick search of old bookmarks and came across this:

http://www.sae.org/technical/papers/2002-01-3308

Basic SAE suspension design. A friend of mine built an SAE car a number of years ago and we came across this book.

He never ended up buying it, so I can't vouch for its content... but its a thought

Cheers

-Aaron

[Chubbs]

awesome thanks!

the project is part of my second year race car engineering module and as it is coursework we wont be making it into a real car and the information i posted is all the information i have been given.

We can decide on al the rest ourselves but it has to be realistic. I think im going to base it on our 07 formula student car as the front suspension was the same kind of setup. Its one of the mre interesting projects we have been given so im keen to get going on it!

cheers for your help!

[Belatti]

I´ll answer your "where would i start?" question:

Locate "centro de balanceo" position (please help me with that translation, its balance center?) define car aporx. weight, desired static ride height, cog, then a little of calculus, to get aprox. suspension travel values, you will have to work arround the loop till you get what you want.

With that you can draw the basic lines and most critical points to visualize geometry (first paper, then autocad 3D or similar is more than enough).

Once you have got a simple "beam" model, if you can, use a finite elements software, like Ansys and run a simulation.

Thats basically what I did three years ago in a project, but with a big bus instead of a formula car.

[Chubbs]

I´ll answer your "where would i start?" question:

Locate "centro de balanceo" position (please help me with that translation, its balance center?) define car aporx. weight, desired static ride height, cog, then a little of calculus, to get aprox. suspension travel values, you will have to work arround the loop till you get what you want.

With that you can draw the basic lines and most critical points to visualize geometry (first paper, then autocad 3D or similar is more than enough).

Once you have got a simple "beam" model, if you can, use a finite elements software, like Ansys and run a simulation.

Thats basically what I did three years ago in a project, but with a big bus instead of a formula car.

awesome, thanks a lot!

[RH1300S]

I don't know if this will help; it is designed to allow calculations for Race Sims (rFactor).

http://www.kangaloosh.com/cms/

[Chubbs]

yeah that looks pretty cool ill give it a go thanks!