## Spring theory Design Question?

## Spring theory Design Question?

(OP)

Hello All-

I have a question regarding spring design theory and was wondering if you all could help.

I am reasearching spring design for a project and came across an article which can befound here...

www.clc.tno.nl/projects/recent/spring.html

The article pertains to making a composite spring. My question is can the eqautions and principles shown in the article be used in designing a hollow core metal spring with an exotic metal such as Titanium?; or are there a different set of formulas and factors that need to be used?

I have looked everywhere i can think to but have not been able to find info that is valid.

If anyone could point me in the rite direction it would be greatly appreciated.

Thank you for your time

Paul

I have a question regarding spring design theory and was wondering if you all could help.

I am reasearching spring design for a project and came across an article which can befound here...

www.clc.tno.nl/projects/recent/spring.html

The article pertains to making a composite spring. My question is can the eqautions and principles shown in the article be used in designing a hollow core metal spring with an exotic metal such as Titanium?; or are there a different set of formulas and factors that need to be used?

I have looked everywhere i can think to but have not been able to find info that is valid.

If anyone could point me in the rite direction it would be greatly appreciated.

Thank you for your time

Paul

## RE: Spring theory Design Question?

## RE: Spring theory Design Question?

Thank you very much

## RE: Spring theory Design Question?

You indeed can use the same formulas however, remember that the wire section moment of inertia is smaller due to the hollow core. You have to update the formula to take into account the core hole diamter inside the wire. Since the spring force and rate formulas are already "cooked" formulas based on solid wire you will need to know how those formulas developed to be able to update them for the hollow core wire.

## RE: Spring theory Design Question?

## RE: Spring theory Design Question?

I looked again in the artcle and you are right, it gives the formulation for hollow core wire with the correct J. However, for Strong1 to use it properly he needs to apply Wahl factor to account for stress concentration due to wire curvature.

As you said these formulas neglect Wahl factor therefore they will fit for springs with a ratio of the spring diameter to the "wire" diameter (10:1 or greater). Sorry for missunderstanding your first post.

## RE: Spring theory Design Question?

Paul

## RE: Spring theory Design Question?

I have one more question and then i will leave you alone :)

Would the same principles and eqautions as well as wahl factor be used to design a hollow core RECTANGULAR SPRING?...I.E. the inner spring of a valve spring on some engines valve train.

I apologize for all the question but really appreciate your help.

If they are different eqautions would you be so kind as to say what they are? I really havent had any luck finding pertanent information.

Thank you

Paul

## RE: Spring theory Design Question?

## RE: Spring theory Design Question?

http://www.webspawner.com/users/israelkk/

## RE: Spring theory Design Question?

It is possible to make such designs with advanced manufacturing techniques.

## RE: Spring theory Design Question?

## RE: Spring theory Design Question?

The only eqaution i have been able to find regarding Wahl factor is as follows...

W=4C-1 0.615

____+______

4C-4 C

Is this correct?

My reference material has not arrived as of yet.

Thank you

Paul

## RE: Spring theory Design Question?

http://www.webspawner.com/users/israelkk/

## RE: Spring theory Design Question?

The design equations can be adapted from those for hollow torsion bars, which SAE publishes.

I eventually concluded that the space efficiency for a shock spring declined enough to negate the weight advantage. Getting seamless tubing of sufficient strength is another problem. I finally just went back to titanium and super-high strength steels for the tough applications.

Titanium is a fun spring material, but it requires a superbly clean surface before it goes into the vacuum furnace, and that may tough on a piece of tubing.