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Some problems on bi-material computation using solids4foam

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Old   December 14, 2022, 21:43
Default Some problems on bi-material computation using solids4foam
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Yang Xueliang
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Hi everyone,
Recently, I have become very interested in solids4foam to study geotechnical problems and try to implement various applications of multi-layer soil in it. The first thing I learned was the bi-material problem, which has been implemented in solids4foam with examples. But when I tried some modifications, I encountered some problems. I hope you can give me some advice or guidance.

First of all, I want to know what principle is used to write the fields into the time folders in the bimaterial examples. Why is the output D, epsilon, Sigma, pointD etc.? However, the volFields defined in the mechanicalLaw by me cannot be output in the time folders. What is the reason for this?

Secondly, I tried to use multi-layer soil in the stripfooting example, which involves multi-material. But when I ran it, there was an error which said that
request for volScalarField p from objectRegistry soil1Subset failed, available objects of type volScalarField are 2(sigmaHyd p0).

I'm not very clear at the moment. Could you please give me some suggestions or directions to think about?

These questions seem very simple, but they are very important to me. I hope you can express your views.
Thanks all.
Young
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Old   December 21, 2022, 11:12
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Philip Cardiff
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Hello Young,

See my replies below:

Quote:
Originally Posted by Youngxl View Post
First of all, I want to know what principle is used to write the fields into the time folders in the bimaterial examples. Why is the output D, epsilon, Sigma, pointD etc.? However, the volFields defined in the mechanicalLaw by me cannot be output in the time folders. What is the reason for this?
These outputs are:
  • D: total displacement
  • DD: increment of displacement (total displacement minus old-time total displacement)
  • epsilon: total strain
  • sigma: total stress
  • pointD: D defined at the mesh points; most solid models calculate D at the cell-centres; many of them have procedures for interpolating these displacements to the vertices to produce pointD. Note that ParaView will also generate a point field D, which it interpolates to the points.

Based on this comment, I have created an issue on GitHub at https://github.com/solids4foam/solid...b.io/issues/40.

In multi-material cases, solids4foam creates a mechanical law for each material; it also creates a "sub-mesh" for each material. In that case, fields within a mechanical law are defined on the sub-meshes, not on the entire mesh, so they are not automatically viewable by ParaView. It should not be an issue to find a solution for this; for example, a new function object could look up the law fields and map them to base mesh field for visualisation. Feel free to create an issue at the GitHub page and we can discuss solutions there.

Note that you can still output the mechanical law fields to the time directories, however, they will be written to sub-directories of the time directories.

Quote:
Originally Posted by Youngxl View Post
Secondly, I tried to use multi-layer soil in the stripfooting example, which involves multi-material. But when I ran it, there was an error which said that
request for volScalarField p from objectRegistry soil1Subset failed, available objects of type volScalarField are 2(sigmaHyd p0).
Please give more details of this case. I guess you may be using a poro-solid model and poro-elastic mechanical law. If so, there may be some issue for multi-material cases that needs to be fixed.

Philip
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