SfePy May 2013

sfepy@python.org

5 participants
17 discussions

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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1D line elements in SfePy
by Nimish 22 Jan '16

22 Jan '16

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

4 9

Python 3 compatibility
by Robert Cimrman 11 Aug '14

11 Aug '14

FYI: As SciPy 0.12.0 is out and one of the release highlights is "Support for Python 2 and Python 3 from the same code base (no more 2to3)", we can think seriously about updating SfePy in this respect as well, cf. [1]. r. [1] https://github.com/sfepy/sfepy/issues/164

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Evaluate a solution in the arbitrary point in the domain
by Alec Kalinin 03 Apr '14

03 Apr '14

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

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elliptical hole under isotropic stress
by David N. Mashburn 13 Jan '14

13 Jan '14

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

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possible GSoC project ideas
by Robert Cimrman 06 Jun '13

06 Jun '13

Hi, we are trying to sign up under the PSF umbrella for this year's Google Summer of Code because of an e-mail from Ankit Mahato, who expressed interest to help developing SfePy as his GSoC project this summer. So let us discuss possible project ideas here. I will post results of the discussion to [1]. Ankit's ideas are (my summary): #1 parallelization - cluster support using mpi4py #2 pre- and post-processing GUI frontend #3 incorporating phase changing materials (his research area) Ankit, could you post full text your ideas into this thread? The pdf you sent me does not allow selecting text. My comments: For me, #1 is something that I was planning to do "soon" anyway as I am going to need it for my research work - a help would come really handy, but we will have to think carefully about the implementation. I think I prefer having a parallel layer above the current serial FEM, so that the current code can stay as it is, unaware that it runs in parallel. I am not sure yet how difficult it is going to be, but it won't be trivial. #2 would be nice, but IMHO it is not so important as having a solid and reasonably fast FEM core. #3 would IMHO be the most useful for Ankit, and a nice addition to modelling capabilities of SfePy. Other possible topics can be found in our issues list ("enhancement" label). IMHO it would be good to prospective student(s) to try tackling some of the issues listed below to get acquainted with SfePy code before the GSoC starts: #196 Document properly term evaluation modes and postprocessing/probing. #195 describe how to add Neumann BC in a diffusion example and tutorial (tutorial part done by Alec) #167 improve gallery page #164 Python 3 compatibility #154 automatic testing of terms #140 test schroedinger.py #133 Provide examples for SfePy Terms Implementing the other enhancements would be, of course, also very useful, but those IMHO too difficult for someone trying to learn the code. They are certainly quite difficult for me, as they are not done yet =:) (shell elements!) Cheers, r. [1] http://sfepy.org/doc-devel/development.html

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verbosity...
by steve 29 May '13

29 May '13

Is there an easy way to dial down the verbosity of sfepy in particular during the "Probe" steps? I tried what I thought were some sensible things (e.g., 'verbose':False in the problem def options) etc., but nothing seems to work. I did notice the pull request on github for a 'verbose' patch, but it looks like it's not quite ready yet. Sorry if this is a dumb question! ;-) thanks, -steve

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memory error during probe?
by Steve Spicklemire 29 May '13

29 May '13

I'm using sfepy to solve for the potential in what is essentially a cylindrical lens for charged particles. I'm attempting to use a probe to evaluate the field components (-grad(u)). Here's what I'm attempting: def GetFieldAtPoint(res, x, y, eps=0.1): """ Return the field strength at a point x,y using eps for centered difference. """ probe = PointsProbe(( (x + eps, y), (x - eps, y), (x, y + eps), (x, y - eps)), res.pb.domain.mesh) pars, vals = probe(res.var) vals = vals.squeeze() Ex = (vals[1]-vals[0])/(2.0*eps) Ey = (vals[3]-vals[2])/(2.0*eps) return np.array([np.isnan(Ex) and 0.0 or Ex, np.isnan(Ey) and 0.0 or Ey]) But I'm getting a memory exception after several evaluations. I'll try to come up with a complete example to post.. but has anyone see this kind of trouble? thanks, -steve Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_INVALID_ADDRESS at address: 0x00000000130e16a0 0x0000000108513b1f in __pyx_f_5sfepy_3fem_7extmods_5bases_find_ref_coors (__pyx_v_ref_coors=0x10cb28b90, __pyx_v_cells=0x10cb28b40, __pyx_v_status=<value temporarily unavailable, due to optimizations>, __pyx_v_coors=<value temporarily unavailable, due to optimizations>, __pyx_v_ics=0x108521e60, __pyx_v_offsets=0x111c0a870, __pyx_v_iconn=0x10f152450, __pyx_v_mesh_coors=0x10cb330c0, __pyx_v_conns=0x110e3ce60, __pyx_v_eref_coorss=0x10e153950, __pyx_v_nodess=0x10e144638, __pyx_v_mtx_is=0x110e3cdd0, __pyx_v_allow_extrapolation=1, __pyx_v_close_limit=0.10000000000000001, __pyx_v_qp_eps=1.0000000000000001e-15, __pyx_v_i_max=100, __pyx_v_newton_eps=1e-08, __pyx_skip_dispatch=0) at build/src.macosx-10.6-intel-2.7/sfepy/fem/extmods/bases.c:5795 5795 __pyx_v_ig = (*__Pyx_BufPtrCContig1d(__pyx_t_5sfepy_3fem_7extmods_5types_int32 *, __pyx_bstruct_iconn.buf, __pyx_t_37, __pyx_bstride_0_iconn)); (gdb) bt #0 0x0000000108513b1f in __pyx_f_5sfepy_3fem_7extmods_5bases_find_ref_coors (__pyx_v_ref_coors=0x10cb28b90, __pyx_v_cells=0x10cb28b40, __pyx_v_status=<value temporarily unavailable, due to optimizations>, __pyx_v_coors=<value temporarily unavailable, due to optimizations>, __pyx_v_ics=0x108521e60, __pyx_v_offsets=0x111c0a870, __pyx_v_iconn=0x10f152450, __pyx_v_mesh_coors=0x10cb330c0, __pyx_v_conns=0x110e3ce60, __pyx_v_eref_coorss=0x10e153950, __pyx_v_nodess=0x10e144638, __pyx_v_mtx_is=0x110e3cdd0, __pyx_v_allow_extrapolation=1, __pyx_v_close_limit=0.10000000000000001, __pyx_v_qp_eps=1.0000000000000001e-15, __pyx_v_i_max=100, __pyx_v_newton_eps=1e-08, __pyx_skip_dispatch=0) at build/src.macosx-10.6-intel-2.7/sfepy/fem/extmods/bases.c:5795 #1 0x0000000108516b89 in __pyx_pf_5sfepy_3fem_7extmods_5bases_3find_ref_coors (__pyx_self=<value temporarily unavailable, due to optimizations>, __pyx_args=<value temporarily unavailable, due to optimizations>, __pyx_kwds=<value temporarily unavailable, due to optimizations>) at build/src.macosx-10.6-intel-2.7/sfepy/fem/extmods/bases.c:6310 #2 0x00000001000c1e7d in PyEval_EvalFrameEx ()

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gsoc 2013
by Robert Cimrman 28 May '13

28 May '13

Good news everyone - Ankit Mahato's proposal has been accepted for this year's GSoC! r.

2 1

what is the oldest Python version in use?
by Robert Cimrman 27 May '13

27 May '13

Hi, I am using Python 2.7 - is anybody using an older version? Just curious. r.

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SfePy May 2013