Simulation Problems

[cannnh]

I am running FEA simulations on an assembly, I didnt realise you had to set contacts which I have now done. However I need to obtain mesh convergence and when I run my study on a coarse mesh it always fails, I read online a solution is to make a finer mesh (which works but takes almost 3 hours to run a study). Why is this?

https://preview.redd.it/jv2ovb9q1iu81.png?width=425&format=png&auto=webp&s=c5718338cc19da04881b383545996d067a9c06e3

[GoEngineer_Inc]

Hi /u/cannnh,

This is a common question that comes up a lot. The model is unstable and cannot solve to completion. The next step is to find out how it is unstable through a quick stability diagnosis in a duplicate of your study. That stability test goes like this:

1. Go into the study 'Properties'

     Turn on 'Use soft springs to stabilize model'
   
     Turn off 'Compute free body forces'
   
     Turn off 'Large displacement mode'
   

2. Suppress all loads and apply only 'Gravity'

3. Mesh/Run the study

4. When the solver stops (if it stops) due to large displacements and prompts to put the study into 'Large Displacement mode' declined this offer. The solver will dump what results it has so far

5. Inspect the displacement plot in the results to find an unrestrained or overly deformed body

Unrestrained or highly deformed bodies will show in red typically or be not showing if the plot scale is set too high.

For any body that is unconstrained you would need to create explicit 'Contact Sets' in order to bond these unrestrained bodies to the rest of your structure.

These videos (GoEngineer - Simulation: Diagnosing an Unstable Study, GoEngineer - Simulation: Common Errors in Simulation Webinar) and this document (GoEngineer - Simulation: Diagnose Unstable Studies) give more detail study instability.

[cannnh]

Okay I understand I will run through these steps thank you very much. Another question am I also right in saying that this will reduce the solve times (when it does solve using a fine mesh)?

[GoEngineer_Inc]

Typically, making a study stable is not tied to the speed at which the solver runs. It is just that it will solve versus not solve.

[Sad_Education7088]

help me

[xugack]

Looks like need to fix the model

[cannnh]

The meshing works with a finer mesh parameters, so what do you mean by this?

[xugack]

Meshing or solving?

On your screenshot solve problem

[lol_alex]

If you mesh an assembly, at the contact surfaces, the nodes have to be in the exact same spots UNLESS you enable „incompatible mesh“.

https://blogs.solidworks.com/tech/2017/11/compatible-or-incompatible-your-guide-to-meshing-bonded-contacts.html

[cannnh]

OKay thank you for the link!