Plastic snap

Thanks for jumping in @ahmedhussain18!

That’s what I did not notice. Thank you for mentioning! :slight_smile:

Best,

Jousef

How you insert the properties of PC+ABC ?

Hi @daniel11 : So PC+ABS ist not available in the material data base. So i chose only ABS for the first attempt.

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You build the files in Onshape ?

Hi @daniel11 : No, I used Solid Works.

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Hello @ahmedhussain18 : We’re you able to find out the problem?
kind regards

Hey @fbernhardt!

Yes! so far I am able to perform until the point it is about to snap properly. After which the simulation diverged every time. I will probably try to do it with a little friction if it may help the immediate sliding to occur less. But this may include more complexities. Below is the figure of the final step of the performed simulation:

Please find the link to the project here: SimScale

You can of course copy the project and try to solve it further.

Best,
Ahmed

sir, can you explain about the formula in brief?

Hi @Omer!

Formulas like these are time-dependent meaning that they are incrementally increased over time.

Example: -0.0036t means that at the last time step (which is 1) the displacement “condition” in z-direction of -0.0036[m] will be fulfilled starting at 0 displacement at the initial time t=0. In the next step you will have -0.00360.05[m] and so on.

Hint: Initial time step length [s] is defined in the “Simulation Control” option in the Simulation Designer.

Does that make sense?

Cheers,
Jousef

thanks, Josef.
here 0.05 is in auto time stepping?
secondly, in static analysis, is run time different from the time “t” mentioned above?

Hi @Omer,

yes it is. The runtime and time stepping time are quite different. That makes sense as the runtime would not set a distinct BC as it varies from run to run.

Best,
Jousef

so from above the distance would increase from 0 to -0.0036 in 1 sec.is my statement correct?

Exactly @Omer!

hi Josef, another query.
can you explain to me why I am getting this error?

Hi @Omer,

try to include the “long surface” into the definition of your slave assignment as depicted in the picture. That should resolve the error. Please let me know if that worked for you.

All the best,

Jousef

Hello @Omer,
I think the main problem in your run is not the master and slave surfaces, but hte very high friction coefficient of 0.6.
Why did you use such a high value? If you put it back to a normal range of about 0.3 it should work just fine.

Best,
Richard

as you told i have reduced the coefficient of friction from 0.6 to 0.2.please can you have a look and suggest me a good option?
thanks
omer

Sure,
this is a new case, so new challenges might appear.

In this case it is relatively easy to find the error cause. If you look at the convergence plots you can see that the absolute residual is very low (~1e-26) while the relative is very high (~1). This hints to the fact that there are actually no forces in your model at all and thus you can not use a relative convergence criteria. In fact, the snap does not move far enough in the first time step to get into contact, so there are no forces at all.

To resolve this, just change in the numerics under nonlinear resolution type the convergence criteria type from relative to absolute.

When this analysis comes to the final stage there are again some problems. This time the master surfaces was missing the rear end surface. After adding this the simulation runs smooth in a few minutes.

Here the link to the resolved project: SimScale

Best,
Richard

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thanks a lot, @rszoeke. you have really helped me a lot.I have never received such a quick response from any community.one thing i want to ask how to understand the convergence criteria?

Nice to hear that @Omer!
You will find some more details on it in our documentation: SimScale Documentation | Online Simulation Software | SimScale

If you still have additional questions I am happy to help!

Best,
Richard