fcFEM - FEA from start to finish
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Re: fcFEM - FEA from start to finish
Got the interface elements working. Identifying the interface elements from FC mesh data and extracting the relevant information was the greatest challenge. The actual finite element implementation is a matter of a few hours.
Example of a sliced block with interface normal stiffness high and shear stiffness zero. The top face is pushed down and restrained in lateral directions, as is the bottom face.
The blocks are assembled in a compound and the Coherence Mesh parameter for the GMSH object is set to FALSE to make sure that two sets of nodes are generated at the interface.
Example of a sliced block with interface normal stiffness high and shear stiffness zero. The top face is pushed down and restrained in lateral directions, as is the bottom face.
The blocks are assembled in a compound and the Coherence Mesh parameter for the GMSH object is set to FALSE to make sure that two sets of nodes are generated at the interface.
Re: fcFEM - FEA from start to finish
And it exports well to VTK / ParaView:
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Re: fcFEM - FEA from start to finish
Harry, give us a break.
Can you explain what you are doing?
No math, just words..
Can you explain what you are doing?
No math, just words..
Re: fcFEM - FEA from start to finish
Hi Thomas,
General/motivation; there are quite a few practical and interesting engineering problems that are hard to do or even impossible with the current FreeCAD/Calculix combination and I don’t think adding more external solvers or waiting for their developer(s) is the answer. For example: mixed meshes (sandwich panels, soil/structure interaction, pre-stressed concrete, bridges), analysis beyond limit points (plastic collapse of frames, plates and soil bodies, non-linear buckling of structures, etc.)
Specific: I built a macro that takes FC mesh and material data and performs the basic tasks of a finite element program. Now I am adding functionality that allows me to do the analyses that were previously out of reach. Zero-thickness elasto-plastic interface elements were high on the list for me as they are a simple and robust alternative for (small deformation) contact problems and can be used in mixed meshes to model the interaction (e.g. cohesive or frictional slip) between 1D/2D structural elements and the surrounding 3D matrix (eg concrete reinforcement, soil anchors, tunnel linings, foundation plates, piles).
Status: basic linear elastic solver framework and curved 2D interface elements work, although I am still running into trouble with more complex contact geometries. This is work in progress.
Next steps: 1) calculate and export stress results (note: interface elements are really handy to visualize contact stresses); 2) extend the solver framework to handle plasticity and collapse (simplest example being the slip and pull-out of structural elements along elasto-plastic interfaces); 3) include simple, traditional, beams and shell elements; 4) include general material and geometric non-linearity for 1D, 2D and 3D elements; 5) Add essential QT5 GUI functionality to provide specific input; 6) Make available for testing.
General/motivation; there are quite a few practical and interesting engineering problems that are hard to do or even impossible with the current FreeCAD/Calculix combination and I don’t think adding more external solvers or waiting for their developer(s) is the answer. For example: mixed meshes (sandwich panels, soil/structure interaction, pre-stressed concrete, bridges), analysis beyond limit points (plastic collapse of frames, plates and soil bodies, non-linear buckling of structures, etc.)
Specific: I built a macro that takes FC mesh and material data and performs the basic tasks of a finite element program. Now I am adding functionality that allows me to do the analyses that were previously out of reach. Zero-thickness elasto-plastic interface elements were high on the list for me as they are a simple and robust alternative for (small deformation) contact problems and can be used in mixed meshes to model the interaction (e.g. cohesive or frictional slip) between 1D/2D structural elements and the surrounding 3D matrix (eg concrete reinforcement, soil anchors, tunnel linings, foundation plates, piles).
Status: basic linear elastic solver framework and curved 2D interface elements work, although I am still running into trouble with more complex contact geometries. This is work in progress.
Next steps: 1) calculate and export stress results (note: interface elements are really handy to visualize contact stresses); 2) extend the solver framework to handle plasticity and collapse (simplest example being the slip and pull-out of structural elements along elasto-plastic interfaces); 3) include simple, traditional, beams and shell elements; 4) include general material and geometric non-linearity for 1D, 2D and 3D elements; 5) Add essential QT5 GUI functionality to provide specific input; 6) Make available for testing.
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Re: fcFEM - FEA from start to finish
This is where my salivating glands got into high gear! I interpret this as crash simulations are within reach? Please say yes!HarryvL wrote: ↑Fri Feb 15, 2019 11:47 pm ...handle plasticity and collapse (and buckling?) (simplest example being the slip and pull-out of structural elements along elasto-plastic interfaces);
3) include simple, traditional, beams (idealized fasteners) and shell elements (isotropic and non isotropic).
4) include general material and geometric non-linearity for 1D, 2D and 3D elements (fiber reinforced sandwiched material).
5) Add essential QT5 GUI functionality to provide specific input (lots of automagical stuff =Ob ).
....
Re: fcFEM - FEA from start to finish
I plan to provide basic finite element functionality and bolt on features if and when needed for a specific design challenge. As this will be FOSS at some point, others can do the same.
Re: fcFEM - FEA from start to finish
Not wanting to get too excited here but I'm getting excited
Alone you go faster. Together we go farther
Please mark thread [Solved]
Want to contribute back to FC? Checkout:
'good first issues' | Open TODOs and FIXMEs | How to Help FreeCAD | How to report Bugs
Please mark thread [Solved]
Want to contribute back to FC? Checkout:
'good first issues' | Open TODOs and FIXMEs | How to Help FreeCAD | How to report Bugs
Re: fcFEM - FEA from start to finish
@Polymer, the above FEA results are not generated by Calculix.