SfePy September 2013

sfepy@python.org

2 participants
9 discussions

Re: Torque
by Robert Cimrman 10 Mar '18

10 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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1D line elements in SfePy
by Nimish 22 Jan '16

22 Jan '16

I am currrently looking for FEM packages to help me solve a system of beams and columns, basically a collection of 1D bernoulli/timoshenko line elements. I started reading SfePy docs and i am getting the idea that doing the above is not really possible here, am i right? Are only 2D area elements permitted in SfePy? Or is there any direct support for solving 1D line elements too.. Cheers Nimish

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Python 3 compatibility
by Robert Cimrman 11 Aug '14

11 Aug '14

FYI: As SciPy 0.12.0 is out and one of the release highlights is "Support for Python 2 and Python 3 from the same code base (no more 2to3)", we can think seriously about updating SfePy in this respect as well, cf. [1]. r. [1] https://github.com/sfepy/sfepy/issues/164

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Evaluate a solution in the arbitrary point in the domain
by Alec Kalinin 03 Apr '14

03 Apr '14

Dear SfePy users, Is it possible to evaluate a solution not only in the FEM mesh node, but in any arbitrary point in the domain with the given (x, y, z) coordinates? For example, consider Dirichlet problem for Poisson equation. We apply essential boundary conditions on the surface nodes and after the problem has been solved we have the solution vector, i.e. vector of values in the FEM mesh nodes. But I want to know the solution in point v(x, y, z) that is not FEM mesh node. What is the best way to obtain solution in this point v? Sincerely, Alec Kalinin

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elliptical hole under isotropic stress
by David N. Mashburn 13 Jan '14

13 Jan '14

Hello sfepy developers and users! I am modelling a simple linear elastic sheet under isotropic stress with an elliptical hole in the center (and I have it working under sfepy, great little platform!). It is obvious the model should initially yield more easily in the direction of the short axis of the ellipse. What is not so obvious to me is what should happen in the limit as stress goes to infinity. Part of me wants to believe that the hole should eventually become a circular, but the results of the simulation show that the ellipse eventually switches its aspect ratio with what was the the short axis becoming the long axis and vice-versa. My question is whether: A: The finite element result is the product of a small-displacement/non-moving mesh artifact (and if so, if there is a way to get the correct behavior using sfepy...) OR B: My intuition about the physical behavior of this ideal system is incorrect and the ellipse really wouldn't round out into a circle under increasingly large stress (aka, the FE model is still physical/correct with large displacements). This might be obvious to people who have done more finite element modeling than I have, but thanks anyway! I'm attaching a picture to make it easier to see at a glance (quarter-ellipse with x and y symmetry boundary conditions and equal tractions applied at the top and right boundaries). Thanks! -David Mashburn

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post process energy calculation
by Anastasia Konovalova 15 Nov '13

15 Nov '13

Hello, sfepy group, I have a question about post-process calculations. For my problem I used the modified examples linear_elastic.py and hyperelastic.py. After the calculation of strain and stress tensors I need to get energy of deformation \int_{V} S : C, where C = 2*E+I. I think I need to calculate the multiplication of tensors first, as some material variable, and then integrate it. So I have 2 questions: 1. How can I calculate the double scalar multiplication of two arrays strain and stress that have shape (number of elements, 1, 6, 1)? (Double scalar multiplication of A and B is a scalar that can be got as A_{ij}B_{ji}). Because of the shape of arrays I can't use numpy.inner(stress,strain). I made some function for these calculation, but perhaps, the simplier way exsists. 2. Then I get the multiplication - the scalar function of energy I should integrate it. For this I get the dw_volume_integrate term. I'm trying to integrate material parameter, where energy has been saved. solid.update({ 'E' : get_W(stress,strain),#energy in elements }) U = problem.evaluate('dw_volume_integrate.i1.Omega(solid.E, v)',) Or may be I should use some new variable and initialize it in post-proc. I'm asking for help in correct formulation of this integral. Should I define energy as material parameter or some new variable? And how I can do it. Thanks in advance,

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GSoC Phase II
by Ankit Mahato 20 Sep '13

20 Sep '13

Hi R, I tried mem_checkIntegrity inside the functions but it is not printing any debugging result. mem_checkIntegrity(421,"convect_build_vtg","termsNavierStokes.c","~/sfepy/sfepy/terms/extmods"); mem_checkIntegrity(546,"term_ns_asm_convect","termsNavierStokes.c","~/sfepy/sfepy/terms/extmods"); Am I adding it correctly? regards.

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ANN: SfePy 2013.3
by Robert Cimrman 18 Sep '13

18 Sep '13

I am pleased to announce release 2013.3 of SfePy. Description ----------- SfePy (simple finite elements in Python) is a software for solving systems of coupled partial differential equations by the finite element method. The code is based on NumPy and SciPy packages. It is distributed under the new BSD license. Home page: http://sfepy.org Downloads, mailing list, wiki: http://code.google.com/p/sfepy/ Git (source) repository, issue tracker: http://github.com/sfepy Highlights of this release -------------------------- - implementation of Mesh topology data structures in C - implementation of regions based on C Mesh (*) - MultiProblem solver for conjugate solution of subproblems - new advanced examples (vibro-acoustics, Stokes flow with slip conditions) (*) Warning: region selection syntax has been changed in a principal way, see [1]. Besides the simple renaming, all regions meant for boundary conditions or boundary/surface integrals need to have their kind set explicitly to 'facet' (or 'edge' in 2D, 'face' in 3D). [1] http://sfepy.org/doc-devel/users_guide.html#regions For full release notes see http://docs.sfepy.org/doc/release_notes.html#id1 (rather long and technical). Best regards, Robert Cimrman and Contributors (*) (*) Contributors to this release (alphabetical order): Vladimír Lukeš

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merge regions branch & next release
by Robert Cimrman 18 Sep '13

18 Sep '13

Hi all, the changes previewed in the "(c)mesh + regions update" thread are almost ready to merge into master. After it is done, I will release sfepy-2013.3, so I would like to hear your feedback, especially on the documentation [1], where the new machinery is described. There are several changes that will have to be done in your problem description files in region definitions: 1. Rename "nodes" -> "vertices", "elements" -> "cells". 2. All regions meant for boundary conditions or boundary/surface integrals need to have their kind set explicitly to 'facet' (or 'edge' in 2D, 'face' in 3D). 3. The logical operators changed too as well as there are some new, see the docs. 4. If no region kind is specified (the 'cell' default), the selector can be a string directly in the short syntax instead of the tuple. Check the examples too (e.g. [2]) to see the new syntax. It's a little bit inconvenient, I know, but the new code is more powerful and simpler that the old one. It will also allow adding new selectors (edge- or face-based) easily, if needed. Best regards, r. [1] http://sfepy.org/doc-test/users_guide.html#regions [2] http://sfepy.org/doc-test/examples/acoustics/acoustics3d.html

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SfePy September 2013