SfePy April 2011

sfepy@python.org

3 participants
7 discussions

Re: Torque
by Robert Cimrman 09 Mar '18

09 Mar '18

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 -- You received this message because you are subscribed to the Google Groups "sfepy-devel" group. To post to this group, send email to sfepy...(a)googlegroups.com. To unsubscribe from this group, send email to sfepy-devel...(a)googlegroups.com. For more options, visit this group at http://groups.google.com/group/sfepy-devel?hl=en.

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tetrahedral refinement
by Robert Cimrman 28 Apr '11

28 Apr '11

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

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Re: Hollow Cylinder Analysis
by Robert Cimrman 17 Apr '11

17 Apr '11

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 -- You received this message because you are subscribed to the Google Groups "sfepy-devel" group. To post to this group, send email to sfepy...(a)googlegroups.com. To unsubscribe from this group, send email to sfepy-devel...(a)googlegroups.com. For more options, visit this group at http://groups.google.com/group/sfepy-devel?hl=en.

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Hollow Cylinder Analysis
by onur alpay 17 Apr '11

17 Apr '11

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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boundary conditions in time
by Robert Cimrman 13 Apr '11

13 Apr '11

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.

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Scientific Python at SIAM CSE 2011 conference (fwd)
by Robert Cimrman 06 Apr '11

06 Apr '11

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

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readthedocs.org
by Robert Cimrman 01 Apr '11

01 Apr '11

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/

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SfePy April 2011