Mailman 3 June 2018 - SfePy

Material Parameters of Individual Nodes
by derj...＠web.de April 12, 2022

April 12, 2022

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 Jan. 17, 2019

Jan. 17, 2019

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 Nov. 6, 2018

Nov. 6, 2018

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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Creating and Adding New Terms
by underwatergary＠gmail.com July 26, 2018

July 26, 2018

Hello there! First of all let me just say that SfePy is such an amazing software and is helping the visualization and solving equations for my research immensely without having to pay the exorbitant amount of money for a comparable software. After familiarizing myself with creating meshes, and running different simulations (in my case mostly Navier-Stokes) I was attempting how to create a way to simulate the Brusselator equations and attempted to create two new terms that would model these equations. After following the very nice tutorial in the Developer's Guide, I mimicked all of the other term files and placed a file "terms_brussels.py" into the terms folder just as the other terms files are and I kept getting errors that there were no such terms as the ones I had made. I also attempted to (rather roguishly) append my new terms into a pre-existing term file. This could just be stupidity or naivety on my part, but how would one go about implimenting a new term that they had made. I have tried looking for more information in the documentation so I apologize if this question is covered there. Cheers, Gregory

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ANN: SfePy 2018.2
by Robert Cimrman June 19, 2018

June 19, 2018

I am pleased to announce release 2018.2 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 or by the isogeometric analysis (limited support). It is distributed under the new BSD license. Home page: http://sfepy.org Mailing list: https://mail.python.org/mm3/mailman3/lists/sfepy.python.org/ Git (source) repository, issue tracker: https://github.com/sfepy/sfepy Highlights of this release -------------------------- - generalized-alpha and velocity Verlet elastodynamics solvers - terms for dispersion in fluids - caching of reference coordinates for faster repeated use of probes - new wrapper of MUMPS linear solver for parallel runs For full release notes see http://docs.sfepy.org/doc/release_notes.html#id1 (rather long and technical). Cheers, Robert Cimrman --- Contributors to this release in alphabetical order: Robert Cimrman Lubos Kejzlar Vladimir Lukes Matyas Novak

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How to output vtk or h5 of compare_elastic_materials.py
by pyontaku14 . June 12, 2018

June 12, 2018

Hi, Is there any way to output vtk or h5 of compare_elastic_materials.py? Best regards, Takuo Fujita

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