SfePy May 2017

sfepy@python.org

4 participants
9 discussions

Material Parameters of Individual Nodes
by derj...＠web.de 12 Apr '22

12 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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Re: Torque
by Robert Cimrman 09 Mar '18

09 Mar '18

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.

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multiphysics: piezoelectric + solid mechanics + acoustic
by firdaus prabowo 22 May '17

22 May '17

Hi, I'd like to try solving multiphysics problem with Sfepy, in particular when a piezoelectric disc attached on a solid vibrates and propagating waves from the solid part to a water domain (acoustic). Is there any example available for a similar problem? I would like to compare the results with COMSOL results (readily available). Thanks. Regards, Firdaus

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question about non-linear solver
by Patricia Garcia Cañadilla 20 May '17

20 May '17

Dear all, I have some questions about the internal behaviour of Sfepy that I hope you can answer me. - What is it the convergence criterion of the non-linear Newton solver? - When modelling a Nearly incompressible Mooney-Rivlin hyperelastic material, like the example shown here: http://sfepy.org/doc-devel/examples/large_deformation/hyperelastic.html, how the nearly-incompressibility constraint is stabilised? Thank you very much in advance.

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ANN: SfePy 2017.2
by Robert Cimrman 19 May '17

19 May '17

I am pleased to announce release 2017.2 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 -------------------------- - simplified and unified implementation of some homogenized coefficients - support for saving custom structured data to HDF5 files - new tutorial on preparing meshes using FreeCAD/OpenSCAD and Gmsh 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 Jan Heczko Lubos Kejzlar Vladimir Lukes Matyas Novak

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Re: Problems with Linear Elasticity Example
by Robert Cimrman 09 May '17

09 May '17

On 05/09/2017 01:36 AM, Jeshwanth.Kundem(a)wagner-group.com wrote: > You are right about scikit-umpfack being installed somewhere else. I removed > it and it worked as you mentioned in the previous email. OK. Now if you do a fresh scikit-umfpack install, does it help? > I will check the example. > > I have to disagree with the Anaconda statement. I tried, tried and tried > with Anaconda. It might be an easy install, but what is happening is the > Anaconda is at 4.3.1. When I install sfepy through conda forge channel, the > sfepy or conda forge wants the anaconda to be 4.2.13 or something. For that > reason, it gave me an option mentioning "The packages will be superseded by > a higher priority channel" and it is actually trying to get back to 4.2.13. > Because of this lot of anaconda packages are being unlinked with conda. They > are causing other problems down the line, with mayavi, wxpython, serial etc. > I would like to know what you think about my statement. I am not aware of any such anaconda version dependence in the sfepy recipe - maybe some of the dependencies need that. Anyway, I am not sure how to solve that. If you happen to find some more information, let us know. > Are you mentioning that if I use conda, I would not have the scikit-umfpack > problem and UMFPACK would work without any errors? If so let me know, I will > give it a try once again. It might. I did not try it recently, but that was the idea. If it does not work, submit an issue to the package that fails, please. r. > Because of this I intentionally deleted anaconda and installed python and > packages one by one with pip. > > > > > > -----Original Message----- From: Robert Cimrman [mailto:cimrman3@ntc.zcu.cz] > Sent: Monday, May 08, 2017 5:03 PM To: Kundem, Jeshwanth Cc: > sfepy(a)python.org Subject: Re: [sfepy] Problems with Linear Elasticity > Example > > On 8.5.2017 23:34, Jeshwanth.Kundem(a)wagner-group.com wrote: >> Hi Robert >> >> The example works when I change the ls solver from scipy_direct to >> scipy_iterative. Not when I uninstall scikit-umfpack. It is apparently not >> being defaulted to scipy LU solver. Any thoughts on this? However, I am > > If you remove scikit-umfpack and still see the same error, I would guess you > have another version of scikit-umfpack installed somewhere. > >> unable to specifiy the number of iterations if I change to >> scipy_iterative. > > See examples/diffusion/cube.py for an example of how to set the number of > iterations. > >> The UMFPACK has to be installed before using sckit-umfpack. There is no >> good documentation on that . I got onto this website: >> http://faculty.cse.tamu.edu/davis/suitesparse.html . However it is only >> available for MATLAB and C. > > How did you install python and other sfepy dependencies? (Which versions?) > The easiest way nowadays is to use anaconda - there is even a recipe for > sfepy on conda-forge ("conda install -c conda-forge sfepy" should work). > > r. >

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Re: Problems with Linear Elasticity Example
by Robert Cimrman 08 May '17

08 May '17

On 8.5.2017 23:34, Jeshwanth.Kundem(a)wagner-group.com wrote: > Hi Robert > > The example works when I change the ls solver from scipy_direct to > scipy_iterative. Not when I uninstall scikit-umfpack. It is apparently not > being defaulted to scipy LU solver. Any thoughts on this? However, I am If you remove scikit-umfpack and still see the same error, I would guess you have another version of scikit-umfpack installed somewhere. > unable to specifiy the number of iterations if I change to scipy_iterative. See examples/diffusion/cube.py for an example of how to set the number of iterations. > The UMFPACK has to be installed before using sckit-umfpack. There is no good > documentation on that . I got onto this website: > http://faculty.cse.tamu.edu/davis/suitesparse.html . However it is only > available for MATLAB and C. How did you install python and other sfepy dependencies? (Which versions?) The easiest way nowadays is to use anaconda - there is even a recipe for sfepy on conda-forge ("conda install -c conda-forge sfepy" should work). r.

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Problems with Linear Elasticity Example
by Jeshwanth.Kundem＠wagner-group.com 08 May '17

08 May '17

Hi I am trying to work out the example located on the following webpage http://sfepy.org/doc-devel/primer.html#sec-primer I am only trying to do the first piece of code, I am getting the following error and I am completely unsure what the problem is. I tried uninstalling and installing scikit-umfpack like bunch of times. Still do not know what the problem is. Any help would be appreciated on how to install umfpack. Other examples are running fine, except this one and elasticity is the only important problem for me. [cid:image001.png@01D2C813.8ECF9BB0] Regards Jeshwanth

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SfePy May 2017