Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Accordion Spring design

Accordion Spring design

Accordion Spring design

I am looking out for generalized design procedure for Accordion spring.
I looked into the web a lot but couldn't find information regarding the same.
It would be of great help if experts out there could guide me through the same.

RE: Accordion Spring design

What do you mean when you say 'accordion spring'?

Please provide a drawing or a representative photograph.

Mike Halloran
Pembroke Pines, FL, USA

RE: Accordion Spring design

Same post was asked in thread 404-416836 sometimes ago. Hope you will find more. But as I said then this is basically a flat strip folded. As to my best >35 years of experience I didn't see a closed form formula for such a spring. You can always use FEA. But if it is for large deflections it may be tricky. Can you give some info on the use of this spring?


RE: Accordion Spring design

The spring to be used in one way starter clutch.
The deflection isn't large.
I am not getting how to start with calculations for the required load.
We can achieve the required load by trial and error. But, I don't want to do that thing.
I want to standardize the design procedure for this kind of spring.

RE: Accordion Spring design

Why are you looking for such spring which is not a common spring?
What is the force and deflection you need?
What is the space you have for the spring?
Did you consider other type of springs such as Helical Compression etc.?

RE: Accordion Spring design

We have space constraint & this spring can serve our purpose well.
It reduces assembly time in the end product.
Have higher life expectancy.
These kind of springs are available with only certain vendors worldwide and has to be imported.
I want to develop this kind of spring in our place and use it.
Forming of the spring is comparatively easier (Need your advice)
Min load required to start compression of spring is 0.17N
7.6mm is the place available for placement of spring.
I tried with helical compression spring, Rectangular spring.But, they all have space constraint in my end application.
I have only two option left
1) Find appropriate calculation for Accordion spring.
2) Re-design the product, which is a tedious task again.

So, I would like to go with option 1. If that isn't favorable only then I can move on with option 2.

Waiting for your advice.

RE: Accordion Spring design

The load 0.17N and 7.6mm space are not enough information. Lets assume a helical compression spring.

1. What is the maximum spring diameter you can allow?
2. What is the maximum spring compressed length when compressed by 0.17N?
3. How much more compression (extra travel) is needed during work?
4. What is the force needed at the second load point (after the extra travel)?
5. Are there any requirements for the inside diameter of the spring or just the outside?
6. How many life cycles the spring has to live?
7. Environmental conditions?

And any more info you can give.

Producing a helical compression is very common and very cheap the larger the quantity the cheaper the spring.

RE: Accordion Spring design

Advice - two parts:

1) hire someone with sufficient FEA experience to do the job.
2) have a long talk with the company who already fabricates this type of spring. They are the experts.

RE: Accordion Spring design


Assume that I have bent a sheet metal of 0.1mm thick, 9.4mm height & 3mm width to form a "V" with an angle of say 20°.
Now, definitely, I can have a spring action when I try to compress the top ends of "V" provided the material is elastic. Let's assume that the material is AISI 304.
Now my question is how can I calculate the possible deflection because of this kind of profile?
I searched many sources for the same & also I tried to assume it as a cantilever beam and tried to find the deflection. But, I failed in it since I didn't get appropriate results.

I am sure that FEA has the answer for this. But, I am not sure from where shall I begin the quest.

RE: Accordion Spring design

You should be able to model the spring as a series of cantilevers, each of which has a concentrated load and a moment at its distal end.

Regarding the 180 degree turns at each fold:
To a first approximation, I would ignore them, just assuming they are rigid enough to transmit the axial force unmolested, and contribute little to the deflection.
To a second approximation, I think you can also model the 180 turns at each fold as a short cantilever, using the developed length of the turn as the cantilever length, i.e., unwrapping the turn for local calculation purposes, and sort of rewrapping the turn, rotating the direction of the force, for combination with the next 'leaf' in order to eventually get the overall deflection.

It's the sort of thing you can do in Excel if you beat on it long enough.

There is another complication; these springs are normally used inside of a rectangular or arcuate cage. I.e., they are not really stable like columns under axial load, but must be constrained by some surrounding structure, so you may have to model the turns as not a pure cantilever, but as a cantilever that may or may not have a support roughly midway along its (developed) length. That may make the force summations more, uh, interesting.

As noted several times already, the shortest/fastest path to getting what you want is to get in contact with someone who is already in the business of making these springs, and, er, develop a commercial relationship with them. Doing otherwise will feed your ego if you succeed, but will also probably cost you years.

Mike Halloran
Pembroke Pines, FL, USA

RE: Accordion Spring design

If I understand you correctly the spring is "V" shape both sides 9.4 mm long, 3 mm width and 0.1 thick. The maximum deflection each side can have until the 20 degree angle is closed is 1.63mm. The force to deflect one arm 1.63 mm is 0.3N. Because you have two arms it means two springs in series, the force to bring both arm to contact will be 0.15N. According to your previous posts, 0.17N is the initial force but you didn't give deflection requirements pass the 0.17N initial force. Your current "V" spring will not do the job because at 0.15N the spring can no longer move. If you add more folds to the spring the force will decrease accordingly while the deflection will increase.

From the the above mentioned data, you at least can have a helical spring 3 mm diameter and 3.2 mm long at 0.17N load. According to my quick check this can be done with a helical spring made of round wire. I took the liberty to press the spring extra 2 mm travel beyond the 0.17N to reach 0.33N with no problem including fatigue.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now
The Great Project Profitability Debate
A/E firms have a great opportunity to lead the world into the future, but the industry’s greatest asset—real-time data—is sitting wasted in clunky, archaic ERP platforms. Learn how real-time, fully interactive dashboards in a modern ERP allow you to unlock data that will shape the future of the world. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close