SfePy July 2012

sfepy@python.org

6 participants
8 discussions

by Robert Cimrman

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.

2 years, 12 months

1D line elements in SfePy

by Nimish

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

5 years, 1 month

Modeling an adjustable X-ray optic

by Tom Aldcroft

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

7 years, 9 months

Stabilized Navier Stokes Inflow+Outflow = Almost Singular Matrix

by John C. Hart

If I alter the example file stabilized_navier_stokes.py to include an outflow boundary condition (in addition to its inflow) by adding the line: 'Outlet_velocity' : ('Outlet', {'u.1' : -1.0, 'u.[0,2]' : 0.0}), to the ebcs, then the oseen solver doesn't converge, and I get: "warning: (almost) singular matrix! (estimated cond. number: 1.5e+19)" Is there an issue using both inflow and outflow boundary conditions with the oseen solver? Thanks, -John

8 years, 7 months

generate mesh from mocap file and volum of mesh at each step

by henri

hi every one, I would like to use sfepy for a new project In this project i use a mocap file ( with 52 points (x,y,z) recorded during 2 minutes) I would like to make a mesh of this points every second and be able to get volume and the surface changes My problem is to generated the mesh can you give me a idea about how build my code to generate the mesh and use it in sfepy? best regards henri

8 years, 7 months

Nonlinear parameters

by David N. Mashburn

Hello Developers, I am trying to understand how to adjust the parameters in the Nonlinear (Newton) solver. I'm good on "imax" since it's the number of iterations before abort and I think that "eps_a" is the maximum allowable absolute sum total residual before ending the sim (??), but I'm not at all clear on what the other parameters do and how they override each other. I've dug through the docs and looked at the source, but I'm also still unclear about which parameters will be applicable in different situations. Could you all point me to the right information? Or better yet just summarize what each of the parameters does and when it is applicable? nls = Newton({ 'i_max' : 1000, 'eps_a' : 1e-10, 'eps_r' : 1.0, 'macheps' : 1e-16, 'lin_red' : 1e-2, # Linear system error < (eps_a * lin_red). 'ls_red' : 0.1, 'ls_red_warp': 0.001, 'ls_on' : 1.1, 'ls_min' : 1e-5, 'check' : 0, 'delta' : 1e-6, 'is_plot' : False, 'problem' : 'nonlinear'} , lin_solver=ls, status=nls_status) Thank you! -David

8 years, 7 months

simplifying integral definition

by Robert Cimrman

Hi, following the issue [1], the dimension in the integral name (e.g. 'gauss_o2_d2') is now useless. Moreover, we do not have any other kind of quadrature than Gaussian(-like). So what about leaving just the order, that is, instead of integrals = {'i1' : ('v', 'gauss_o2_d3')} we would have integrals = {'i1' : ('v', 2)} What do you think? r. [1] https://github.com/sfepy/sfepy/issues/191

8 years, 7 months

Got 15 minutes and want to learn Git?

by Md. Golam Rashed

Git made easy in this 15 minutes tutorial. I should learn it soon. http://try.github.com

8 years, 8 months

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SfePy July 2012