How to fix (and apply loads) to nodes of FEM mesh
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Re: How to fix (and apply loads) to nodes of FEM mesh
before you can convert the mesh into a solid you may need to convert your femmesh into a mesh by invoking FEM_FemMesh2Mesh
Re: How to fix (and apply loads) to nodes of FEM mesh
Hi just FYI i'm still working on this. Trying different approaches here's some notes
- I can't remesh with gmsh or netgen, they cannot mesh these kinds of structures. I wrote my own code for the meshing.
- still a few things to try. i'm working on my mesher to get pure flat faces at the ends.
- i'll update asap
thanks.
- I can't remesh with gmsh or netgen, they cannot mesh these kinds of structures. I wrote my own code for the meshing.
- still a few things to try. i'm working on my mesher to get pure flat faces at the ends.
- i'll update asap
thanks.
Re: How to fix (and apply loads) to nodes of FEM mesh
Do you have the geometry as step or brep without meshed surface? OR Are you able to create mesh groups of nodes or mesh groups of elements with your meshing code?tcdoe wrote: ↑Sun Jun 02, 2019 6:44 pm Hi just FYI i'm still working on this. Trying different approaches here's some notes
- I can't remesh with gmsh or netgen, they cannot mesh these kinds of structures. I wrote my own code for the meshing.
- still a few things to try. i'm working on my mesher to get pure flat faces at the ends.
- i'll update asap
thanks.
Re: How to fix (and apply loads) to nodes of FEM mesh
Hi well not so good.
Got everything into a part as per previous suggestions.
Also finally figured out how to mesh the top and bottom to enforce coplanar triangles (well that's good! now we have supported edges!!). But still can't assign triangles/faces or select the whole top face (or bottom), or otherwise make a simple fixed and force/disp boundary condition on portion of mesh.
I think it's time to give up. If I can't assign boundary conditions to nodes or similar sections of the mesh (or even through any other means), then it is a no-go. No way to define the analysis. I think it's kind of weird that all of this work is done on freecad, but this most-basic functionality is left out, totally crippling the software.
thanks for all suggestions.
t.
Got everything into a part as per previous suggestions.
Also finally figured out how to mesh the top and bottom to enforce coplanar triangles (well that's good! now we have supported edges!!). But still can't assign triangles/faces or select the whole top face (or bottom), or otherwise make a simple fixed and force/disp boundary condition on portion of mesh.
I think it's time to give up. If I can't assign boundary conditions to nodes or similar sections of the mesh (or even through any other means), then it is a no-go. No way to define the analysis. I think it's kind of weird that all of this work is done on freecad, but this most-basic functionality is left out, totally crippling the software.
thanks for all suggestions.
t.
Re: How to fix (and apply loads) to nodes of FEM mesh
Not so fast!Please have a look at this example.
The mesh is imported from mesh.unv
Constraints are applied to faces made by FreeCAD's Part WB
That's all.
- Annotation 2019-06-05 102636.png (29.43 KiB) Viewed 2118 times
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Re: How to fix (and apply loads) to nodes of FEM mesh
@_UR:
good one
@tcdoe:
For you it is the most-basic functionallity because in your workflow you need it. Most other FreeCAD FEM user have a different workflow, because they have the geometry in FreeCAD. Thus they do not need to define constraints on the mesh. Thus this has not been implemented so far. Might be if someone really needs it, someone will implement it.
Have a look at the example of _UR, it solves your problem in a simple and smart way.
bernd
good one
@tcdoe:
For you it is the most-basic functionallity because in your workflow you need it. Most other FreeCAD FEM user have a different workflow, because they have the geometry in FreeCAD. Thus they do not need to define constraints on the mesh. Thus this has not been implemented so far. Might be if someone really needs it, someone will implement it.
Have a look at the example of _UR, it solves your problem in a simple and smart way.
bernd
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Re: How to fix (and apply loads) to nodes of FEM mesh
Pardon the resurrection, but I have this same issue, but I don't have geometry.
The most common way to apply loads and boundary conditions to finite elements, in my experience with FeMap, Patran, and Abaqus, is to do so with the finite element data, not geometry. Geometry is a convenience that may be used to more easily group finite element data and select finite element data, but it is not the default way it is organized within the pre-processor. CFD tools tend to do this kind of geometry first organization a lot, but structural analysis software does it far less, in my experience.
In a practical setting, it is exceedingly rare to have the exact geometry all of the time, as if you did, there would be no point in doing more analysis, as the final geometry was clearly not subject to change, pending the results of a structural analysis which uses finite elements.
In the same way that it is needed to be able to operate on imported dumb-solids like STEP files and IGES files, the same is true of finite element data.
Was there a workflow that existed which created solids from finite elements? If so, would any of you be able to link me to it? This seems to be the necessary stopgap measure to do analysis on finite element data at all. If FreeCAD possesses the performance necessary to render each finite element entity as its own "CAD" entity so that it can always maintain association, I believe then that we might not need orphan mesh handling tools at all.
Alternatively, given that we now have the ability to create node sets, which, correctly, does not need geometry, why can we not simply apply nodal finite element data to those nodesets? In Nastran/Mystran, this is exceedingly simple, as each node in a node set would have its own SPC, or FORCE card added to the bulk data deck accordingly.
The most common way to apply loads and boundary conditions to finite elements, in my experience with FeMap, Patran, and Abaqus, is to do so with the finite element data, not geometry. Geometry is a convenience that may be used to more easily group finite element data and select finite element data, but it is not the default way it is organized within the pre-processor. CFD tools tend to do this kind of geometry first organization a lot, but structural analysis software does it far less, in my experience.
In a practical setting, it is exceedingly rare to have the exact geometry all of the time, as if you did, there would be no point in doing more analysis, as the final geometry was clearly not subject to change, pending the results of a structural analysis which uses finite elements.
In the same way that it is needed to be able to operate on imported dumb-solids like STEP files and IGES files, the same is true of finite element data.
Was there a workflow that existed which created solids from finite elements? If so, would any of you be able to link me to it? This seems to be the necessary stopgap measure to do analysis on finite element data at all. If FreeCAD possesses the performance necessary to render each finite element entity as its own "CAD" entity so that it can always maintain association, I believe then that we might not need orphan mesh handling tools at all.
Alternatively, given that we now have the ability to create node sets, which, correctly, does not need geometry, why can we not simply apply nodal finite element data to those nodesets? In Nastran/Mystran, this is exceedingly simple, as each node in a node set would have its own SPC, or FORCE card added to the bulk data deck accordingly.