Upright ball joints

[Shelby67]

Hi guys,

We are designing a FSAE and I have to design the suspension elements. All dynamic calculus are finished, but I have to design uprights, wishbones, pushrods…

My question is about ball joints how can I calculate the size I need?

I think I must take the loads at the contact patch and translate them to the joints, but if I do that the forces at joints are very high. I’m thinking that it could be because my loads at the contact patch aren’t right.

My critical loads for a 290kg car are:

Longitudinal Load: 1.400N
Lateral load: 960 N
Vertical load: 1.200 N

Are too high?

Please say me if the “my process “ is wrong.

Kind regards.

[Shelby67]

Hi guys,

We are designing a FSAE and I have to design the suspension elements. All dynamic calculus are finished, but I have to design uprights, wishbones, pushrods…

My question is about ball joints how can I calculate the size I need?

I think I must take the loads at the contact patch and translate them to the joints, but if I do that the forces at joints are very high. I’m thinking that it could be because my loads at the contact patch aren’t right.

My critical loads for a 290kg car are:

Longitudinal Load: 1.400N
Lateral load: 960 N
Vertical load: 1.200 N

Are too high?

Please say me if the “my process “ is wrong.

Kind regards.

[Gruntguru]

Lateral sounds a bit low. At 1.5 G your total lateral is about 4,400 N and most of that will be shared by the two outside wheels. (Yes I have seen a FSAE car corner on two wheels)

[exFSAE]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">but if I do that the forces at joints are very high </div></BLOCKQUOTE>

Define "very high" for us, in this context.

[Shelby67]

After calculations, the joints must support around:

229 KN in the vertical direction
2200 N in longitudinal direction
1660 KN in lateral direction.

I think they are too high. I have revised my equations and I can’t find any mistake.

Thanks for answering.