Help designing Upright, Hub, Pushrod, Spring and Shock!

[Cockrocket]

Hello

I am currently in my 2nd year of university at Liverpool doing product design and for one of my modules the class joins in groups of 6 - 7 of other engineers to design parts for a Formula Student car.

http://www.imeche.org.uk/formulastudent/

my group has been tasked with desgning the rear part of the car and so each member of the group has been given an area to design. The areas include the brakes, body work, tranmission, exhaust and the suspension which is split into 2. I m doing the suspension and the parts i must design are as follows
- The upright and hub assembly
- Pushrod assembly
- Spring and shock absorber assembly

The rules of the module state i am able to buy in parts as long as their is suitable justification for them. So that will include the spring and shock absorber assembly. That leaves the hub, pushrod and the uprights for me to design. The problem is i do have a certain knowledge about cars but for this technical level of detail i am lost. Does anyone know of websites or are able to post up themselves images and information that will help me understand the role and purpose of each of these components and when i come to designing my own what they need to include. I would appreciate any help as long as it is sensible.

Regards

William Day

[kjekki]

are you using solid works to to the design?
just completed a suspension in solid works, just for fun though. learnt the program on school, but the things we make are boring.
i dont think my model is really well made tough :?

[Cockrocket]

No we will be using Pro Engineer Wildfire 3.0 to complete the models 100% accuratly, but we will not be using the package to design them, sketching and research is how we will be coming up with the final design then once made in Po E, adjustments will be made in that program so my suspension parts fit pefectly to the bake system made by anothe team mate etc. I ahve heaed of Solid Woks but the packages we are being tained are Pro Engineer and 3D Studio Max 8 - 9

[T-Bird]

what do you mean by the pushrod assembly? I'm sure this is just a translation thing (yes from England English to US English) I understand the Upright to be the hub assembly or spindle.

[number77]

You need to go to the library. The info you're looking for won't be found on this forum.

[coombsie66]

All i can say after working on a formula student project for two years is research, research, research. Look at what other teams have done in the past, see what has worked, buy a decent suspension design book, i have this one which i would recommend highly
Competition Car Suspension: Design, Construction, Tuning: Amazon.co.uk: Allan Staniforth: Books

You have to design your suspension first, which will be entirely determined by the pick up points that you will be able to position on the rear spaceframe chassis of the car, then you are limited by how large you can make the upright and therefore the positions of the pickups on there (u running 10" or 13" wheels? the guy designing our suspension told me that it is a struggle to get everything into a 10" and find tyres, but they are ultimately a better bet for performance).
Luckily you dont have to worry about steering as you are doing the rear, but that is an absolute ballache!

the detailed design of the Hubs, uprights, wishbones and pickups come after youve finalised your rear suspension geometry. you'll need a suspension design geometry program such as susprog to be able to try out different designs.

As for the detailed design, dont try and re-invent the wheel and think of the costs involved in manufacture (costing carries a lot of marks in the FS event).
But i'd advise rear hubs similar to any front wheel drive car hubs you'll see, internally cut spline into which the outboard CV joint bolts and a flange with a radiused section reducing down to a smaller diameter passing through two tapered roller bearings mounted in the upright. I'd CNC turn the hub from a high grade aluminium, and the best cheapest, easiest to alter way of making the upright is fabricated steel.
Make the wishbones from T45 tubing, do stress analysis on them to see how small you can make them, with welded in threaded inserts in either end to accept the rod ends on the inboard suspension pickups, the outboard bearings will be determined by how you are attaching the upright to the wishbones!


Basically, if you are lost, get help, call up previous years designers, research other cars, ask for help from tutors, cus if you plough on regardless without knowing what you are doing, at best you'll have a heavy shite handeling car, and at worst it will break and injur a driver or someone else.

Good luck with it though, it'll teach you things that nothing else at university will, i recommend it to any mechanical engineering student!! (Who is willing to work and has a good sense of humour!) :wink: :P

[TNT]

http://en.wikipedia.org/wiki/Shock_absorber

http://en.wikipedia.org/wiki/Multilink

http://en.wikipedia.org/wiki/Car_parts