T-bar instead of U-bar

[Aaphree]

Hey everyone, I am trying to design a T-bar ARB. Our team wants to move away from the U-bar, but I am having some difficulty getting started. Any tips/advice on where to get started? Any help would be greatly appreciated

[Brett MacPherson]

Why?

10 char

[Simactive]

Why?

10 char

Why not

[Pat Clarke]

Aaphree,

Who are you? What University do you represent? It is rude to anonymously barge in and ask blindly for 'advice'!

Secondly. what is 'different' (better or worse) about either of those anti roll devices? Both are fundamentally torsion springs that resist roll.
They are not the only solution and there have been very many successful FS/FSAE cars that have no such devices at all!

So, tell us what research you have done, what your chassis/suspension design is like, why your team wants to 'move away' from a 'U' Bar?

Then you might get some sensible answers!

Pat Clarke

[Aaphree]

Aaphree,

Who are you? What University do you represent? It is rude to anonymously barge in and ask blindly for 'advice'!

Secondly. what is 'different' (better or worse) about either of those anti roll devices? Both are fundamentally torsion springs that resist roll.
They are not the only solution and there have been very many successful FS/FSAE cars that have no such devices at all!

So, tell us what research you have done, what your chassis/suspension design is like, why your team wants to 'move away' from a 'U' Bar?

Then you might get some sensible answers!

Pat Clarke

I am a student at Penn State, and am on the suspension team for FSAE. This is my second year participating, and first time actually designing anything for the car.

Previously I modeled the A-arms in Solidworks and machined some parts, but this is the first time I've had a major job to do for the team.

The suspension team leader told me he wants to go to a T-bar design instead of our U-bar which we have used in the past. He didn't give many reasons as to why, and he is always in a rush when I catch him,
so I haven't been able to get any specific reasons out of him.

The little information I have been able to gather is that the T-bar is easier to tune, and potentially could lead to more aerodynamic suspension setups...although I'm a bit skeptical on that last one.
Also, they can give a lower antiroll rate than a conventional setup with the same bounce rates. Beyond that, U-bars seem to be more reliable and require less maintenance, and are more common and potentially easier to design.

I don't have the specifics on our entire setup, I missed our meeting this week due to an exam, but that is essentially all I have to work with at the moment. Assuming we use a similar setup to last year, our dampers in the front are
mounted parallel to the ground and the length of the car.

I apologize for just barging in without giving any background information.

[JulianH]

The suspension team leader told me he wants to go to a T-bar design instead of our U-bar which we have used in the past. He didn't give many reasons as to why, and he is always in a rush when I catch him,
so I haven't been able to get any specific reasons out of him.


I don't have the specifics on our entire setup, I missed our meeting this week due to an exam, but that is essentially all I have to work with at the moment. Assuming we use a similar setup to last year, our dampers in the front are
mounted parallel to the ground and the length of the car.

I apologize for just barging in without giving any background information.

Well, to be honest, I'm a bit speechless.
I expected to hear a story from a first year team from India/China/Africa but not from a team that is around "forever".

If you are responsible for the ARB, why is he telling you to do this or that design? Isn't it your goal to learn the design process as well?
It's not like a "well we don't have money for a new engine, we will have to stick to the old one". It's a cheap detail solution...

Look at the big picture: Is maybe a T-Bar necessary due to space issues? If not, than make your own research: Why should I go T-bar? There are a lot of books out there which give you at least a hint.
If you come to the same conclusion (In the design event, it helps to say "I want the T-bar BECAUSE XY" not only "Yeah T instead of U for the win") than do it your way. If not, than you go to him and ask what his deal is...

In the end, Pat is right. They both do the same, you can make fast adjustable solutions for both designs or even win FS Germany without them (Delft 2013).


Good luck!

[Pat Clarke]

Aaphree,
Like Julian, I am shocked. I would have bet money you were from a new Indian team! Your apology is certainly accepted.

And again I agree with Julian. How many points do you think you will get in Design when the judge asks you about your decision to use a 'T' bar and your response is 'The Suspension Team Leader told me to'?

Your statement "Assuming we use a similar setup to last year, our dampers in the front are mounted parallel to the ground and the length of the car" has me wondering how you can go about designing an anti-roll system anyway? What roll are you trying to 'anti'?

Cheers

Pat

[Claude Rouelle]

"The suspension team leader told me he wants to go to a T-bar design instead of our U-bar which we have used in the past. He didn't give many reasons as to why, and he is always in a rush when I catch him,
so I haven't been able to get any specific reasons out of him"

That is so surprising that its is very funny!

So you expect the readers of this forum to be more available than your own suspension team leader? So you look for answers outside because you are not able to get answers inside, correct?

This is not design judging but, as design judge, I can't help to think this reflects poorly on your team organization and coordination.

OK here is the answer: It is because "T" comes before"U" in the alphabet!

More seriously and maybe some answer: weight, packaging, manufacturability, accessibility, adjustability...? But seriously speak to your team member(s) first.

A far as Delft winning FSG 2013 they did not win "because" they did not have any ARB! You guys are reversing the arguments. They won for many other good reasons, the main one is that that were able to modifying their yaw moment by distributing their 4 tire Fx with the torque vectoring of their 4 electrical engines instead of changing the Fz of their tires with ARB (which in turn do influence their tires Fx and Fy, traction ellipses shape).

I still believe a team has an advantage to independently tune its front and rear heave and roll (and ideally pitch) stiffness and in a perfect world independently its front heave, roll and pitch damping. Even with a 4WD and good torque vectoring.

[Aaphree]

In response to Claude,

I don't expect the people of this forum to be more readily available than my team, I only wanted some outside thoughts into this issue. Obviously I need to discuss this more in depth with the team, but since I am on my own at the moment I wanted to try and get as
much info as possible (including opinions of others). I apologize if I made it sound like I am asking the forum instead of working with my team (obviously that isn't proper teamwork/organization!). I appreciate everyone's input, whether it's critical or supportive. I have a lot to learn, and all of this is feedback is quite helpful.

Hearing from a design judge has made me see some things that we can improve on (communication). Thanks for your feedback!

[Aaphree]

Pat and Julian,

Thanks for the tips, having never been to a competition, I didn't think of all of the things that the judges would be looking at. Based on everyone's responses, I have a better idea at what I need to look into to go about this design.

Thanks everyone for your feedback. If anything, it's given me some insight into what needs to be done before even trying to design this ARB.