Suspension design validation suggestions for CAPSTONE course

[Anvit Garg]

Hello:

I have selected the FSAE suspension as a senior design project. I have been trying to figure out all the ins and outs of suspension design, which is more difficult with zero faculty support and no vehicle dynamics courses.


I am having issues specifying a realistic goal for the statement of work. My group members have suggested a sort of test rig that could display a quarter car model.

We were thinking that the rig could display camber behavior and possibly frequency response?

I was wondering if you guys had any suggestions as for physical validation for the allotted time (this semester).

Thanks!

[Anvit Garg]

Hello:

I have selected the FSAE suspension as a senior design project. I have been trying to figure out all the ins and outs of suspension design, which is more difficult with zero faculty support and no vehicle dynamics courses.


I am having issues specifying a realistic goal for the statement of work. My group members have suggested a sort of test rig that could display a quarter car model.

We were thinking that the rig could display camber behavior and possibly frequency response?

I was wondering if you guys had any suggestions as for physical validation for the allotted time (this semester).

Thanks!

[Mike Macie]

Does it have to be a physical validation method?

I think it would be easier to write a program in matlab or even build a suspension model using simulink. It will give you more options on what you can output and you don't have to worry about any data acquisition equipment.

[Anvit Garg]

Ironically, our program does not allow us to learn any CAD or hands on, but the senior design project requires something to be built.

I was thinking that we could still do the simulink model and then validate it with some sort of rig.

I just am not too motivated to build a rig since it will not help with the car project in general. I think the instructor is trying to get us to learn that theory never really makes it to reality without major difficulty.

[frenzy]

why don't you build an "alignment rig" to verify/tune the various settings of the suspension?
I guess that will help a lot with the final setup as all the simulations are worthless when you're not able to verify the correct setup!

[Anvit Garg]

frenzy:

so basically something where I can move the pick up points and adjust various things such as caster, scrub, to study camber behavior without regard to the frequency response or load behavior?


I guess that could also be a good educational tool if the team survives.


Also what do you guys think about practicality, am I being over ambitious or can I throw some more on the plate?

To clarify, my current project states design of a suspension from scratch (picking the points), and building a rig.

Originally, I wanted to have the front and rear suspension built and a chassis to go along with it. We felt that a rolling chassis might be too ambitious. But then again we have never done this project.

[Zac]

I think building a K&C or Four Post rig is a little too ambitious for a first year team.

a better option might be to get a rolling chassis together with several possible configurations and to find a sponsor with a K&C rig(they are out there) to let you test them out.

[BillCobb]

How about modeling the steering wheel torque of a generic FSAE car and mapping the effects of Cardan joint angles, Ackermann, camber, caster, kingpin inclination, and gear friction? You could "borrow" an existing car and run the box of parameters and publish an "I told you so: paper.

[exFSAE]

This is going to be for the following year?

Maybe design up a real slick adjustable suspension, either one for the following car, or one that can be substituted on the current car (a better option if you can pull it off).

Do some analysis using what tire data you have, try to figure out an "optimal" setup. Set the car up for that, do some driving and do a DOE in a few dimensions (caster, camber, ride height, pressures, whatever) to map out vehicle performance, and see if you nailed it.

Even just a DOE on tires and longitudinal grip would be pretty useful.. testing different configurations of inflation pressure, damper settings, and ride height and seeing the 75m time. If you have the money, add a couple tires into the matrix. At the very least, do a few runs on each setup, take all the data, do some statistical mumbo jumbo on em... take a look at which setups are most consistent, which are fastest, if they're truly different at some confidence level, blah blah.

[Anvit Garg]

Here is the problem, we do not have access to any FSAE vehicle, and we have never built one on our own. (The project is due May 2009)

We proposed the following rig, with a type of cam that can simulate an almost sinusoidal wave input:

http://img.photobucket.com/albums/v412/daconfusion/rig.jpg


But I do not think the type of driving the vehicle will be subjected to will really care about sine response (bumps) when compared to other things such as camber due to lateral force, steering forces, and etc.

I have another meeting with the instructor, I will see what he has to say, please keep sending me your inputs. I truly appreciate your suggestions.