Re: Torque
by Robert Cimrman

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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1 year, 1 month

1D line elements in SfePy
by Nimish

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
3 years, 2 months

Evaluate a solution in the arbitrary point in the domain
by Alec Kalinin

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
5 years

elliptical hole under isotropic stress
by David N. Mashburn

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
5 years, 3 months

post process energy calculation
by Anastasia Konovalova

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,
5 years, 5 months

GSoC Phase II
by Ankit Mahato

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.
5 years, 7 months

ANN: SfePy 2013.3
by Robert Cimrman

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
5 years, 7 months

merge regions branch & next release
by Robert Cimrman

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
5 years, 7 months