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A
aal-kerdi1-Visitor
1-Visitor
August 25, 2016
Question

How come the "pushingforce" drops to zero at the peak of the snap?

  • August 25, 2016
  • 2 replies
  • 4898 views

Hello,

I don't seem to understand why the results are as shown in the attached picture. I'm performing a contact analysis in Creo 3.0 Simulate; the force increases as it should but the when the structure has moved down about 3mm the force drops to zero and then increases again.

How can I fix this problem?

Would it help to do a finer mesh in the area of contact?

Thanks.

- Ahmad


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2 replies

A
aal-kerdi1-VisitorAuthor
1-Visitor
August 25, 2016

I tried changing element size at contact areas and i guess i got a better result, but it still goes to zero.efter element size.PNG

J
JonathanHodgson13-Aquamarine
13-Aquamarine
August 25, 2016

Are you using finite friction in your contacts?

A
aal-kerdi1-VisitorAuthor
1-Visitor
August 25, 2016

yes, with a static coef. of friction at 0.6

S
sdensberger2-Explorer
2-Explorer
August 29, 2016

Can you provide more information about the nature of the problem you're looking at? It's hard to tell from the image(s) you've posted, but what could be happening is that you're experiencing a 'snap-through' effect. These are dynamic events, where the path is driven by the inertial forces, which is something that you're not going to capture accurately in a static (or quasi-static) analysis.

You can try to take finer steps around where it goes to zero, but this could potentially cause convergence issues. Mechanica does have a 'snap-through' option to try resolve some of the convergence issues, but the last time I checked (which was maybe a year ago), this option was essentially broken.

A
aal-kerdi1-VisitorAuthor
1-Visitor
August 30, 2016

think of it as a cylinder where you push down a snap. This means that the snap doesn't actually "snap in" it simply "slides" into the cylinder. Could it really be the snap through effect for this case?

I'll definetly try to run the analysis with finer steps.

thanks.

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