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[solidMechanics] Support thread for "Solid Mechanics Solvers added to OpenFOAM Extend"

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Old   August 6, 2022, 03:32
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Ashish Magar
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Did you also try the ./tutorials/solids/elastoplasticity/impactBar tutorial case? It might be helpful.

Yes I did. That was my first step in doing dynamic mesh with rigid body motion. I am using same method for plastic deformation using file "plasticStrainVsYieldStress".

So I made this change:

1. Made "floor" patch as master instead "falling_obj". Previously it was other way around with rigidMaster set to no.
2. Added relaxation for DD equation as well.
3. Added alternativeTolerance and materialTolerance to constant/solidProperties
4. I am using infoFrequency as 1, to see how the convergence of res and relRes is going


Still the issue was there, only the relRes is going down, res remains 1 and after a few timesteps relRes diverges in around 150-200 correctors. I have given a high value for correctors to check whether it comes down at some point.




From the previous example I did, the falling_obj started from rest and moved with effect of gravity only. Now from the impactBar case I used setFields and gave some velocity. Now it runs perfectly fine, atleast it came beyond the point it had crashed before and the mesh also moves.







Thanks for your help.
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Old   August 6, 2022, 09:07
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Another query.. How to select a proper time step for solids only simulation?
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Old   August 9, 2022, 13:02
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Another query.. How to select a proper time step for solids only simulation?
When using an implicit solid solver, then temporal accuracy is the main concern.

A quick check is to re-run your simulation where you double or half (or do both and run two extra simulations) and see if your results change much.
If you want to perform a more formal check, then you can use the Grid Convergence Index (GCI) method (Roache 1996) using the results from three time-step sizes to estimate the time-step independent solution.
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Old   August 10, 2022, 01:40
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Hi Phillip, thanks for your response.


My concern was the simulation crashes within a few or few hundred timesteps if I use a lower one. The run is not stable and I have tried varying DD relaxation. The mesh is clean with few non-ortho cells, other than that it passed all mesh checks. All are tet cells generated using Salome meshing.
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Old   August 27, 2022, 07:19
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Also is there is ordering syntax to follow when having a multi contact body in solidContact BC?
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Old   August 31, 2022, 13:34
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Also is there is ordering syntax to follow when having a multi contact body in solidContact BC?
The solidContact boundary condition uses a node-to-segment type of approach, where it calculates the distance between the "slave" vertices (so called nodes) and "master" faces (so called segments).
As a result, if you switch the master and slave definitions, you may end up with a slightly different solution; however, this difference should dissapear as the mesh is refined.

In terms of deciding which patch should be the slave, you can use trial-and-error to find which works best, or, if one patch has a finer mesh then that tends to be a good choice for the slave (as the algorithm uses the slave vertices).
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