Simulate: Force / Displacement Diagram for non ideal spring

[ptc-4273428]

Hi everyone,

I failed solving the following problem. I reseached for posibilities now for 1 1/2 days but I didn't get it. Hopefully you can give me some good advice on following problem.

My main goal is to get a Force - Displacement Diagram of a single part. It should be somehow like this:

... and this is the situation:

on the one side the part is fixed in all directions. On the other side it is fixed in y and z direction. So finally it behaves somehow like this:

Video Link : 5830

So my "input" is the force and I want to know the dependant displacement at the tip of this part.

What I tried yet:

• Using Creo mechanica. This failed totally, i don't see any method to simulate a single part with that.
• Creo Simulate
  • Static analysis: works fine but only for one single point in my diagram...
  • dynamic time analysis: This seems to be the only method, to get a time-dependant analysis. I used "measurements" to analyse the displacement. But I don't find any useful Tutorial to do it the right way. I time dependant diagrams, but there happens nothing. The Displacement is always 0. I have no idea why.

Does anybody have a good idea how to solve this?

Thank you a lot,

Daniel

[JonathanHodgson]

There is no Creo Mechanica that I know of; it's just had a name change: Pro/Mechanica became Creo Simulate. Not sure what happened - did you start Mechanica in Independent mode?

If you're looking for non-linear results then you'll have to run some form of non-linear analysis. In this case, I think you'll have to enable Large Displacement Analysis (LDA) (within Static Analysis).

I can't remember whether you can create a ramped force application - look for a button with an "f(x)" symbol. You can create a measure for the displacement at the tip, and then in results you should be able to choose 'graph' as the display type.

HTH...

[ptc-4273428 · Accepted solution]

Thank you for your help so far.

The deformation in fact is not only in Y direction:

And I also use "Measures". For the Static analysis this works fine (for one specific value...):

The Material i actually use is Nylon (PA).

_____________________________________________________________________

OK I got it now!

The solution therefore is to use the Large Displacement Analysis (LDA). Thank you Jonathan, for this valuable hint.

One very important thing terefore was, to define my material as Elastoplastic. Otherwise the simulation doesn't run.

Before defining the static analysis I set the measurements. "displacement" "absolute" at the tip...

(sorry, pictures are in german)

and as the sum of all forces in one direction has to be = 0, the reaction force at the left arm has to be equals the "current" force applied on the right arm. So I added a reaction-force-measurement there.

Than I defined a static analysis.

and I defined a linear function for the load.

I chose "Graph", measurement (reaction Force) & measurement (displacement) for my diagram.

And that's how I got the Force-Displacement Diagram.

Thank you guys for your help!

Daniel

[JonathanHodgson]

Glad you got it working!

I think you could have used the built-in "Ramp" function; you could also define a larger number of steps (under "Ausgabe", I think), to get a curved graph.

I'm not sure why you had to set the material to elasto-plastic - I've definitely run LDA with linear materials.

[ptc-4273428]

Yes, that's the next step for me to do, to increase the time steps.

I just checked it once more: When using a linear material creo tells me that it can't calculate it as there are no non-linear elements in my simulation. So what? I just added a stress limit of 100 MPa and it worked.

Maby i also could have chosen other non-linear elements (loads/ constraints/ connections...) but like this it just got a little more realistic.

So thank you again 🙂

[hjung-2]

Hi,

I am a design engineer from Korea, and baby in English.

I wanted to get a force-displacement graph like you. So I read your post many times, and tested by myself with simple beam model for test. But I just could get graphs that have X-axis indicating length of the beam, not increasing force.

Also, It is difficult to find exactly same dialogue box in my Creo and your desired graph in your post even if regarding that your capture image is in German.

Could you show me the way to get the force-displacement graph in another way?

Best regards,

HJ