SfePy February 2013

sfepy@python.org

2 participants
6 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

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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Modeling an adjustable X-ray optic
by Tom Aldcroft 21 May '13

21 May '13

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

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ANN: SfePy 2013.1
by Robert Cimrman 27 Feb '13

27 Feb '13

I am pleased to announce release 2013.1 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. The code is based on NumPy and SciPy packages. It is distributed under the new BSD license. Home page: http://sfepy.org Downloads, mailing list, wiki: http://code.google.com/p/sfepy/ Git (source) repository, issue tracker: http://github.com/sfepy Highlights of this release -------------------------- - unified use of stationary and evolutionary solvers - new implicit adaptive time stepping solver - elements of set and nodes of set region selectors - simplified setting of variables data For full release notes see http://docs.sfepy.org/doc/release_notes.html#id1 (rather long and technical). Best regards, Robert Cimrman and Contributors (*) (*) Contributors to this release (alphabetical order): Vladimír Lukeš, Matyáš Novák

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SfePy February 2013