In examples/large_deformation/hyperelastic.py a rotation by displacements is applied. By using a similar function the vectors defining the force couples could be defined for dw_surface_ltr (IMHO). Does it make sense?
r.
----- Reply message -----
From: "Andre Smit" <freev...(a)gmail.com>
To: <sfepy...(a)googlegroups.com>
Subject: Torque
Date: Sat, Dec 18, 2010 05:10
What is the best way to apply a torque load to a model?
--
Andre
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Hi,
SfePy can now uniformly refine tetrahedral meshes using Domain.refine().
It's quite simple to try - look at 'tests/test_domain.py'. It uses an
algorithm from [1], that prevents spoiling element quality in subsequent
refinements.
r.
[1] Juergen Bey: Tetrahedral grid refinement, Computing 55 (1995), no. 4, 355--378
Hi Onur,
Thanks for your encouragement!
The bad element orientation occurs when an element has a wrong order of vertices leading to negative volume. However this is not your case.
The real problem is that sfepy has no shell elements (yet) - it has 2D elements like triangles, but those are meant to be used in 2D problems, not in 3D like you try. That also answers why there is no thickness...
On the other hand, you might be lucky, as I have recently implemented a Mooney-Rivlin membrane element (membrane = no bending stiffness), which I want to put soon into the master repository. In the meantime, you can try using thin volume elements for your test, if it is possible.
In a longer run, I would like to have the shell elements in sfepy as well, but I know almost nothing about the underlying theory, so any help in this field would be very appreciated :)
r.
----- Reply message -----
From: "onur alpay" <alpa...(a)gmail.com>
To: <sfepy...(a)googlegroups.com>
Subject: Hollow Cylinder Analysis
Date: Sun, Apr 17, 2011 15:10
Hi All,
We are working on the sfepy for about a month. First of all I would like to thank all the developers.
For an example application we have handled a hollow thin cylinder which is subjected to inner pressure.
We have created below files for mesh and run.
But we have some simple questions :).
Our first question is the thickness of the 2_3 Triangular shell elements. We could not find a place the enter the thickness of the tria elements. Sfepy is working quite well with out a thickness input :). But it would be great if we can type it some how...
The second question is about the element orientation. For the same study we are creating a mesh on some other mesher programs and convert the mesh to *.mesh file. But sfepy is throwing Bad Element Orientation! error for this nice mesh :). The only work around could done but using different element size for the same geometry. With enough elements sfepy could re-orient the elements successfully. But we are helpless on using a 3 dimensional geometry. sfepy simply does not re orient the mesh even for different size of elements... :)
Any help would be greatly appreciated.
rc, keep up the good work! Thanks,
Onur
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Hi All,
We are working on the sfepy for about a month. First of all I would like to
thank all the developers.
For an example application we have handled a hollow thin cylinder which is
subjected to inner pressure.
We have created below files for mesh and run.
But we have some simple questions :).
Our first question is the thickness of the 2_3 Triangular shell elements. We
could not find a place the enter the thickness of the tria elements. Sfepy
is working quite well with out a thickness input :). But it would be great
if we can type it some how...
The second question is about the element orientation. For the same study we
are creating a mesh on some other mesher programs and convert the mesh to
*.mesh file. But sfepy is throwing Bad Element Orientation! error for this
nice mesh :). The only work around could done but using different element
size for the same geometry. With enough elements sfepy could re-orient the
elements successfully. But we are helpless on using a 3 dimensional
geometry. sfepy simply does not re orient the mesh even for different size
of elements... :)
Any help would be greatly appreciated.
rc, keep up the good work! Thanks,
Onur
Hi,
I have just pushed in a new functionality concerning boundary conditions.
Now it is possible to specify times in which a particular condition is
active, which enables not only changing the value of a condition,
but also the region where it applies.
Imagine applying a given dislacement to various parts of a specimen in the
course of time.
See also the new examples/diffusion/laplace_time_ebcs.py example.
r.
FYI: some very interesting talks/slides are linked below.
r.
---------- Forwarded message ----------
Date: Wed, 6 Apr 2011 00:26:07 -0700
From: Fernando Perez <fpere...(a)gmail.com>
Hi all,
sorry for the massive cross-post, but since all these projects were
highlighted with talks at this event, I figured there would be
interest... Hans-Petter Langtangen, Randy LeVeque and I organized a
set of Python-focused sessions at the recent SIAM Computational
Science and Engineering conference, with talks on numpy/scipy, cython,
matplotlib, ipython, sympy, as well as application-oriented talks on
astronomy and femhub. For those interested:
- The slides: http://fperez.org/events/2011_siam_cse/
- A blog post:
http://blog.fperez.org/2011/04/python-goes-to-reno-siam-cse-2011.html
- Some pictures: https://picasaweb.google.com/fdo.perez/SIAMCSE2011InReno#
Back to being quiet...
f
FYI...
I have just seen a very nice presentation [1] about writing good
documentation. The presenter mentions Sphinx, but also two things I was
not aware of:
- documentation hosting site [2] - I have already registered, but did not
import sfepy there yet, as we do use custom (numpy) sphinx extensions
- pycco [3] - a literate programming tool.
The talk also stresses that it's primarily the developers who should write
the docs, not the (new) users, so I will get better :)
r.
[1] http://pycon.blip.tv/file/4881071/
[2] http://readthedocs.org/
[3] http://fitzgen.github.com/pycco/
