how to design suspension uprights

[Dharma233]

hii guys

i am participating in SAE Supra india 2016 for first time i have doubts regarding design of suspension uprights. pls explain me what ate the factors to be considered while designing uprights and pls tel me step by step from where to start designing,,
thank u

[DougMilliken]

http://www.fsae.com/forums/showthrea...ead-this-first...

Side note to FSAE.com forum maintainers -- can we have all "first posts" emailed to Claude first?<grin>

[Ahmad Rezq]

Dharma233,
I guess you may receive negative responses. (You may feel bad about that)
Anyway, My suggestion to you is to use the forum search. There are many discussions regarding the Upright Design which may help you to start.

[Claude Rouelle]

Dharma,

1. (....as expected by Doug) And you are....? Worth to introduce your self?
2. Can you use good complete spelling? No texting style here. Please (not pls)
3. Form follow functions. Start with the functions. What are the functions your front and rear uprights are supposed to achieve?
Want some clues?
- What KPI and caster trail do you want and why?
- What caster angle and KPI angle do you want and why?
- Where on the KPI axis do you put your pickup points (I assume you think double wishbone but you could imagine other suspension system)
- Packaging issue: rim size and shape, hub size, bearing type and size, brake discs and caliper choice and dimensions....
- What are your Ackermann and bump-steer choice and how do they influence your toe link outboard point coordinate determination?
- Distance between non suspended mass CG and KPI axis, why is this important?
- What compromise between compliance and weight is acceptable?
- ......
Determine those functions before you open your CAD software!
4. Want to prepare yourself for an engineering career? Is in India SupraSAE the best choice?

[Jonny Rochester]

1. Google it! "FSAE uprights" click on images. Spend a few hours, do nothing but look.
2. Observe the material choices you saw. Note some are machined from aluminium, some are welded plate steel. Why not use wood? Maybe concrete!
3. Find the wheel rims you will be using. Measure them accurately and make a good CAD or 2D drawing of the rim. The rim size and offset will later dictate some packaging and steering angle you get.
4. Find the brake disc and caliper your team wants to use. If this goes inside the wheel rim, this also dictates the packaging. Get good accurate drawings of these components also.
5. Ask the suspension guy what geometry you are using. This may take alot of time to understand.
6. Talk to your team about what forces you will see.
7. Wheel bearings...

[Claude Rouelle]

Couldn't disagree more with you, Johnny. In my opinion, looking on the internet for pictures of "how the others are doing it" is one of the first traps if not THE first trap in which students fall. The pictures you see will imprint if not for ever at least for a long time not only the RAM but also the ROM of your brain., It restricts your imagination. It goes away from the idea of form follow function". It makes you think as a mechanic, a part assembler, not as an engineer, not as a inventor, not as a problem solver. It pushes you away from abstract and creative thinking which is one of the first steps that many students miss. Define the functions, then simulate and calculate, then draw THEN and ONLY THEN, before you go to manufacturing, look at what the others do.

“If I had an hour to save the world. I would spend 59 minutes defining the problem and one minute finding solutions. And I find in most organizations people are running around spending sixty minutes finding solutions to problems that don’t matter”

“Intelligence is the ability to find a solution to a problem you never encountered before. Insanity is doing the same thing over and over again and expecting different results.”

“If I had an hour to save the world. I would spend 59 minutes defining the problem and one minute finding solutions. And I find in most organizations people are running around spending sixty minutes finding solutions to problems that don’t matter”

“We cannot solve our problems with the same thinking we used when we created them”

All these quotes are from Einstein

[Jay Lawrence]

"Whoa, a blue car!"

"I'm somewhere were I don't know where I am"

"Operator, give me the number for 911!"

All these quotes from H. J. Simpson.

If you wait until you're about to manufacture your uprights to study the prior art, you will probably realise you did something stupid and then have to go around in circles at a very late point in the game, and your car will be late and probably not very good. However, to clarify: studying the prior art does not mean turning off your brain and copying, it means seeing what others (note plural) have done and using your brain to decide what's good and bad about them, before coming up with something of your own by using your now more educated brain.

[Claude Rouelle]

Jay, You seem to misinterpret my message. I never told that the "thinking before drawing" process should take months or even weeks. Answering the question "What is an upright supposed to do?" is a matter of days. But it could save you months of disappointment.

Believe me I have been a design judge for years and the abstract/ critical thinking is something missing. I believe in inside out solution (function then form) more than outside in solution (see what the others do and inspire ourselves from it) because you will not know what was in your competitor brain to decide to design what they designed when they designed their uprights. But you can know what is in your brain and what YOUR thought process is, even more if you decide to make it work in a function to form mode.

A very high percentage of students I speak to are not able to answer the simple questions (clues) I posted on my January 11th post (see above)

You will not find creativity on your laptop. Results can only change if if you change the way you think (And these ones are from me)

Claude

[turtle]

The first thing I was taught in my undergraduate engineering career was the engineering design process. Between looking at prior works and generating your own concepts, do both. This should not be viewed as two competing approaches, rather steps in the same problem solving process. Fundamentally it should start with defining the problem.

As to when in this process you should look at other designs depends on who is designing the upright. Considering that the "competitions themselves give teams the chance to demonstrate and prove both their creativity and their engineering skills", the designer should be free to pick an approach to generating a solution that allows the designer to demonstrate creativity and engineering skill. If that means looking at studying and mastering the prior art by looking at previous solutions - that is a reasonable approach and is one way to develop engineering skills. If the designer can demonstrate their creativity and engineering skill by coming up with a design from first principles, that too is a reasonable approach and an excellent way demonstrate the creativity.

Can we tell you how to design an upright? No. Because we don't know what the problem is. It has not been defined. Why are you designing an upright? Do you need an upright? How does designing the upright help you solve the car problem? How does designing the upright help you solve the FSAE competition problem? How does designing the upright help you solve the problems of the team? And if I knew the solution, then I would be making a big assumption about what this permutation of the problem looks like. As much as we would all like to help with the upright design, we are going to need to better understand the problem.

[Claude Rouelle]

Turtle,

"Fundamentally it should start with defining the problem." Bingo!

"....allows the designer to demonstrate creativity and engineering skills" Bingo 2!

"...mastering the prior art by looking at previous solutions - that is a reasonable approach and is one way to develop engineering skill" ....OK but how do you know what is a good upright if you do not know what it is supposed to do, if you have not defined the functions and you only compare forms? Let's also be careful about the Monkey see - Monkey do approach in which many students (especially new ones) also fall "It is a good upright because it is the one of the car that won" used too often

"Because we don't know what the problem is. It has not been defined. Why are you designing an upright? Do you need an upright? How does designing the upright help you solve the car problem? How does designing the upright help you solve the FSAE competition problem? " Bingo 3!

"As much as we would all like to help with the upright design, we are going to need to better understand the problem" Bingo 4! Enough said.