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
--
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.
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, 3 months

Modeling an adjustable X-ray optic
by Tom Aldcroft

I'm working on modeling a next-generation X-ray mirror for which the
shape can be actively controlled by use of many thin piezo-electric
actuators mounted on the mirror surface. The mirror is basically a
glass conical paraboloid with a 1 meter radius and 200 micron
thickness (e.g. http://en.wikipedia.org/wiki/X-ray_optics). Our
project is currently using a proprietary FEA package, but the model
setup and turnaround time is slow, in part because there is only one
part-time engineer who can run it.
SfePy looks like a great package and we're hoping that it could be
used to automate running a large number of different cases. I've
spent some time reading the documentation but I have a few questions
that I hope can be answered before going too much further. I want to
apologize in advance if some of my wording is imprecise, I have a
physics background but this topic is a bit outside my realm...
- Is SfePy appropriate for this problem?
- If a specify a grid with about 800 x 400 points (azimuthal, axial)
and about 10 boundary conditions (corresponding to mount points), what
is the rough order of magnitude of time to compute the solution? Is
it seconds, minutes, hours, or days?
- The linear elastic examples show a problem with a specified
displacement. How do I specify an input force? The piezo essentially
provides a tensile force along the surface.
- Is there a way to specify the problem and solve in cylindrical
coordinates? This is the natural coordinate system.
- How do I specify 6-DOF constraints which correspond to the mirror
mounts?
Thanks in advance for any help!
Tom Aldcroft
5 years, 11 months

Stabilized Navier Stokes Inflow+Outflow = Almost Singular Matrix
by John C. Hart

If I alter the example file stabilized_navier_stokes.py to include an
outflow boundary condition (in addition to its inflow) by adding the line:
'Outlet_velocity' : ('Outlet', {'u.1' : -1.0, 'u.[0,2]' : 0.0}),
to the ebcs, then the oseen solver doesn't converge, and I get:
"warning: (almost) singular matrix! (estimated cond. number: 1.5e+19)"
Is there an issue using both inflow and outflow boundary conditions with
the oseen solver?
Thanks,
-John
6 years, 9 months

generate mesh from mocap file and volum of mesh at each step
by henri

hi every one,
I would like to use sfepy for a new project
In this project i use a mocap file ( with 52 points (x,y,z) recorded during
2 minutes)
I would like to make a mesh of this points every second and be able to get
volume and the surface changes
My problem is to generated the mesh
can you give me a idea about how build my code to generate the mesh and use
it in sfepy?
best regards
henri
6 years, 9 months

Nonlinear parameters
by David N. Mashburn

Hello Developers,
I am trying to understand how to adjust the parameters in the Nonlinear
(Newton) solver.
I'm good on "imax" since it's the number of iterations before abort and
I think that "eps_a" is the maximum allowable absolute sum total
residual before ending the sim (??), but I'm not at all clear on what
the other parameters do and how they override each other.
I've dug through the docs and looked at the source, but I'm also still
unclear about which parameters will be applicable in different situations.
Could you all point me to the right information? Or better yet just
summarize what each of the parameters does and when it is applicable?
nls = Newton({
'i_max' : 1000,
'eps_a' : 1e-10,
'eps_r' : 1.0,
'macheps' : 1e-16,
'lin_red' : 1e-2, # Linear system error < (eps_a * lin_red).
'ls_red' : 0.1,
'ls_red_warp': 0.001,
'ls_on' : 1.1,
'ls_min' : 1e-5,
'check' : 0,
'delta' : 1e-6,
'is_plot' : False,
'problem' : 'nonlinear'}
, lin_solver=ls, status=nls_status)
Thank you!
-David
6 years, 9 months

simplifying integral definition
by Robert Cimrman

Hi,
following the issue [1], the dimension in the integral name (e.g.
'gauss_o2_d2') is now useless. Moreover, we do not have any other kind of
quadrature than Gaussian(-like). So what about leaving just the order, that is,
instead of
integrals = {'i1' : ('v', 'gauss_o2_d3')}
we would have
integrals = {'i1' : ('v', 2)}
What do you think?
r.
[1] https://github.com/sfepy/sfepy/issues/191
6 years, 9 months