SfePy October 2018

sfepy@python.org

6 participants
9 discussions

Material Parameters of Individual Nodes
by derj...＠web.de 11 Apr '22

11 Apr '22

Hello! It's a great tool you built there! I'd like to use it for some kind of topology optimisation. Is there an "idiomatic" way to set the material parameters of individual nodes? Thank you very much! JonnyB

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Calculate total force from cauchy stress
by Patricia Garcia Cañadilla 17 Jan '19

17 Jan '19

Dear Robert, I have a 2D body of hyperelastic material which contracts and I would like to compute the total force developed by the body from the cauchy stress. I am trying to follow some of your indications I found in this group, but I still couldn't make it works. Could you please help me to fix the problem? I am getting the following error: key = (region.name, integral.order, integration) AttributeError: 'dict' object has no attribute 'name' I am trying to do the following, inside stress_strain post-processing function: def stress_strain(out, problem, state, extend = False ): from sfepy.base.base import Struct from sfepy.mechanics.tensors import StressTransform from sfepy.mechanics.tensors import transform_data from sfepy.discrete.common.mappings import get_normals ev = problem.evaluate field = problem.fields['displacement'] region = problem.domain.regions['Gamma'] integral = problem.integrals['i2'] n = get_normals(field,integral,regions) stress = ev('dw_tl_fib_a.1.Omega(f1.fmax, f1.eps_opt, f1.s, f1.fdir, f1.act, v, u )',mode='qp', term_mode= 'stress'); F = ev('ev_def_grad.1.Omega(u)',mode='el_avg'); transform = StressTransform(F) Cstress = transform.get_cauchy_from_2pk(stress) T = Cstress*n; Force = ev('ev_surface_integrate.2.Gamma(T)') And here it is part of the problem configuration file. fields = { 'displacement': ('real', 'vector', 'Omega', 1), } materials = { 'solid' : (None, 'get_elastic_pars'), 'load' : (None, 'linear_tension'), 'f1' : 'get_pars_fibres1', } variables = { 'u': ('unknown field', 'displacement', 0), 'v': ('test field', 'displacement', 'u'), } regions = { 'Omega' : 'all', 'Fix1' : ('vertices in x < %.10f' % (fix_point + eps2), 'facet'), 'Fix2' : ('vertices in x > %.10f' % (fix_point - eps2), 'facet'), 'Fix' : ('r.Fix1 *v r.Fix2', 'facet'), 'Gamma' : ('vertices of surface','edge'), } ebcs = { 'fixb' : ('Fix', {'u.all' : 0.0}), } integrals = { 'i1' : ('v', 1), 'i2' : ('s', 2), }

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Navier - Stokes at high viscosity
by Ben Melosh 06 Nov '18

06 Nov '18

I am trying to model Stokes flow at very high viscosities (~10^20), from my results it looks like I cannot achieve this and am better suited using viscosities of ~10^5 or so. I know there is this older post [1] which states: "A word of warning though: SfePy does not have a dedicated Navier-Stokes solver (the Newton (+ and direct) solver use that is in the navier_stokes.py example is rather naive, and works for small problems with only, with viscosity "high enough")" Has there been a different solver implemented since this was posted? If not, what do you recommend to work with such large viscosities? Thank you [1] "Problem with the mesh while trying to solve the Navier Stokes equations with sfepy"

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Contributing to sfepy development
by Amine Aboufirass 26 Oct '18

26 Oct '18

Dear All, I am a python developer interested in contributing to the sfepy project. There is quite a bit of material in the "How to contribute" page ( http://sfepy.org/doc-devel/developer_guide.html#how-to-contribute). So far I have been able to : - fork repository to my github account - clone forked repository into my local computer - look through issues in sfepy github page for opportunities to help resolve salient issues. I am thinking about this one in particular https://github.com/sfepy/sfepy/issues/367 - Look into forking workflow in Atlassian website ( https://www.atlassian.com/git/tutorials/comparing-workflows/forking-workflow ) - Pursue basic git tutorials. so far I have only experience working with svn vcs. I am confused abut how to properly set up a standalone sfepy development environment in conda. Of course installing a regular environment is easy *conda install -c conda-forge sfepy* The above command seems to take care of all dependencies, including the python installation itself. However I don't understand how this can be combined with *git clone *such that I can install the cloned fork within conda environment. How are the dependencies handled? What of the python version dependency? I do not see these anywhere in the repository, it seems to only contain sfepy scripts and modules. Thanks for your consideration and look forward to hearing from you. Best Regards, Amine

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Mailman
by Phung Huynh Ngoc 16 Oct '18

16 Oct '18

PhungGroup

1 0

Set and Group based regions( was Re: Re: Back after 6.5 years. ;-) )
by Steve Spicklemire 14 Oct '18

14 Oct '18

OK! Thanks so much Robert. I’ve got things back to more or less where they were. One issue I think I never sorted out before was handling boundary conditions in a clean way. I’d like to be able to specify regions symbolically. I see in the docs there’s a concept of vertices in a “group” or “set” but I’m not sure how to create a .geo file that has either “groups” or “sets” defined by lines or points. Can anyone point me to the docs describing how to do this? thanks! -steve Robert Cimrman wrote: > Hi Steve, > > Welcome back :) >

2 1

Coupled phase field and linear elasticity
by Daniel Wheeler 04 Oct '18

04 Oct '18

Hi, I'd like to try and solve the problem outlined here, https://pages.nist.gov/pfhub/benchmarks/benchmark4.ipynb/ Is this a problem that Sfepy could handle? I'm assuming the elasticity part of the problem would be straightforward, but what about a fourth order phase field equation? Given that it's tractable are there examples that match the form of the elasticity equation and/or any Cahn-Hilliard type examples for Sfepy? Cheers, Daniel -- Daniel Wheeler

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Beginning sfepy through conda installation
by Anil Kunwar 03 Oct '18

03 Oct '18

Dear All, I installed sfepy in Ubuntu computer using : conda install -c conda-forge sfepy command, after that I downloaded sfepy by cloning from github. I am trying to run the examples. If I am within the sfepy environment in conda, then how can I execute an input file completely? For example, I run the cube.py using : (mysfepyenv).../path/to/cube.py/directory$ sfepy-run simple cube.py How can I postprocess it? Is it something like this: (mysfepyenv).../path/to/cube.py/directory$ sfepy-run postproc cube.py When I do this, it yields the following message: ModuleNotFoundError: No module named énthought' ... ModuleNotFoundError: No module named 'traits' ... How do I install them? Yours Sincerely, Anil Kunwar

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Back after 6.5 years. ;-)
by steve＠spvi.com 03 Oct '18

03 Oct '18

Hi SfePy folks, I worked on a couple problems using sfepy 6.5 years ago, and then drifted away. Today I tried to run my old code using the latest SfePy and it's mostly broken. ;-( What is the best way to see what's changed since 2012 and how one should go about updating code from that time? thanks! -steve

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SfePy October 2018