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

Kindly Guide
by Jashan Goyal

Hi,
I am Jashan Goyal a 2nd yr graduate at Birla Institute Of Technology
Pilani,INDIA.I want to contribute to sfepy since i am good at coding in
python and wide range of diffrential equations.Please help me how to start
with , I dont have any experience in open source projects.
Thanks
Jashan Goyal
5 years, 3 months

construction of variables update
by Robert Cimrman

Hi all,
following the "Converting a problem description file to direct problem
construction" thread, I have removed the ambiguity in numbers of components of
field vs. variable. What was before
u = FieldVariable('u', 'unknown', field, mesh.dim)
is now
u = FieldVariable('u', 'unknown', field)
The variable's dimensions are given by the field. Nothing changes in the
problem description files.
r.
5 years, 4 months

Converting a problem description file to direct problem construction
by ben

Hello,
Thank you for the time you've put into this project.
I've been solving a particular elliptic PDE by running SfePy on a short
problem description file with: python simple.py problem_desc.py. Now, since
I'd like to do this many times, with different parameters in the problem
description file each time, I'd like to construct the problem directly, by
creating a ProblemDefinition instance, as is done in the
linear_elasticity.py example.
(I'm working with the latest version of SfePy.) I've attempted the
conversion, but clearly something is wrong, as I get a very large residual:
> python direct.py
sfepy: reading mesh [line2, tri3, quad4, tetra4, hexa8]
(../rectangle_fine_quad_r.vtk)...
sfepy: ...done in 0.72 s
sfepy: setting up dof connectivities...
sfepy: ...done in 0.00 s
sfepy: updating variables...
sfepy: ...done
sfepy: matrix shape: (40602, 40602)
sfepy: assembling matrix graph...
sfepy: ...done in 0.09 s
sfepy: matrix structural nonzeros: 723604 (4.39e-04% fill)
sfepy: updating materials...
sfepy: mat_diffusion
sfepy: ...done in 0.06 s
sfepy: nls: iter: 0, residual: 5.209283e+08 (rel: 1.000000e+00)
fish: Job 1, “python direct.py ” terminated by signal SIGTERM (Polite quit
request)
, whereas, using the problem description file:
> python ../../sfepy/simple.py problem_desc.py
sfepy: left over: ['verbose', '__builtins__', 'pdb', '__doc__', '__name__',
'sys', 'data_dir', '__package__', 'refine_mesh', '_filename', 'np',
'__file__', 'math']
sfepy: reading mesh [line2, tri3, quad4, tetra4, hexa8]
(../rectangle_fine_quad_r.vtk)...
sfepy: ...done in 0.69 s
sfepy: creating regions...
sfepy: Omega
sfepy: Expiry
sfepy: ...done in 0.06 s
sfepy: equation "Price":
sfepy: dw_diffusion.2.Omega(mat_diffusion.f, s, p)
= 0
sfepy: setting up dof connectivities...
sfepy: ...done in 0.00 s
sfepy: using solvers:
ts: no ts
nls: newton
ls: ls
sfepy: updating variables...
sfepy: ...done
sfepy: matrix shape: (20200, 20200)
sfepy: assembling matrix graph...
sfepy: ...done in 0.02 s
sfepy: matrix structural nonzeros: 179998 (4.41e-04% fill)
sfepy: updating materials...
sfepy: mat_diffusion
sfepy: ...done in 0.06 s
sfepy: nls: iter: 0, residual: 0.000000e+00 (rel: 0.000000e+00)
I've pared my problem description file and direct approach file down to the
bare minimum. Would you mind having a quick look to see if you can spot the
problem? Otherwise, is there some documentation that would help with the
transition?
Many thanks,
Ben
5 years, 4 months