Hi again!
On 03/03/2012 04:20 PM, Robert Cimrman wrote:
On Fri, 2 Mar 2012, David Mashburn wrote:
Hello again,
I am performing elasticity simulations with boundary forces. I can tell sfepy is capable of this, and starting with the linear_elasticity.py example has already provided a close approximation of what I need, but I am not clear on a couple of things.
My main two related questions right now are:
- Can sfepy apply forces to boundaries instead of to volumes (effectively a von Neumann boundary condition)? What is the prescribed way to do this? I did notice that there is a surface term similar to the volume term, but I was not sure how to use it...
Look at linear_elastic_tractions.py example in the same directory as the linear elastic one.
More specifically, see [1] and [2] .
- Also, what exactly are the "regions" in sfepy? Are they collections of individual mesh elements? If so, is there any way of specifying borders instead? Also, is there a good way way to visualize regions and/or get at the raw data that makes them up? (I am having trouble getting just the)
The regions can define any mesh entity - nodes, elements, etc. if it contains e.g. only surface nodes, it defines the surface faces and can be used for traction forces. Check the user`s guide section about problem description file.
See [3]. To visualize the regions, the best option is to use:
./simple.py <your_input> --save-regions-as-groups --solve-not
and view the created file <mesh name>_regions.vtk with postproc.py. The '--solve-not' option is useful if the input is not finished (e.g. missing equations, conditions, ...) and you just need to verify that the regions are correctly defined.
To see the actual data, the easiest thing is to set a breakpoint in simple.py, line 123 and explore 'print app.problem.domain.regions'. See also [4].
Thanks, -David
BTW, I was not as familiar with quadrature, so I made a small visualizer for the different quadrature tables (I know the formatting will probably get eaten, but you should still get the idea):
Thanks, I will check it when I get to a computer.
Nice, do you think it would be useful to have the images in the docs?
r.
[1] http://sfepy.org/doc-devel/examples/linear_elasticity/linear_elastic_tractio... [2] http://sfepy.org/doc-devel/src/sfepy/terms/termsSurface.html#module-sfepy.te... [3] http://sfepy.org/doc-devel/users_guide.html#regions [4] http://sfepy.org/doc-devel/tutorial.html#interactive-example-linear-elastici...