SfePy November 2016

sfepy@python.org

4 participants
8 discussions

Material Parameters of Individual Nodes
by derj...＠web.de 11 Apr '22

11 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.

4 7

new interactive example with time stepping
by Robert Cimrman 13 Mar '17

13 Mar '17

Hi, I have just updated the time stepping solvers in sfepy for interactive use, as demonstrated in the new example [1]. For basic use, ignore the probing code - the time stepper can be used as simply as: tss = SimpleTimeSteppingSolver({'t0' : 0.0, 't1' : 100.0, 'n_step' : 11}, problem=problem) tss.init_time() for step, time, state in tss(): pass r. [1] http://sfepy.org/doc-devel/examples/diffusion/time_poisson_interactive.html

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Request: enabling "pip install sfepy"
by pyontaku14 28 Nov '16

28 Nov '16

Dear Developers, I have a request. Could you enable us to install sfepy by "pip install sfepy"? This is very simple and helps increasing number of users. Best regards, Takuo Fujita

2 1

Surface Traction term for Navier Stokes
by Nikhil Vaidya 21 Nov '16

21 Nov '16

Hello, I need to use a surface traction term, because I want to apply a pressure dirichlet boundary condition at the inlet for channel flow. In the SfePy term overview page, I can see the term dw_surface_ltr. In my weak form for the Navier Stokes equations, I will need two such terms. One for the stress tensor and one for the pressure. I got the pressure term using the dw_surface_ndot term. I do not understand how to represent the viscosity*vel_test_func.grad(velocity).n term. Best regards, Nikhil

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Piezoelectric/Harmonic Resonance
by Nolan Luckett 11 Nov '16

11 Nov '16

Hello, I am interested in using SfePy for analyzing the resonance modes of a piezoelectric element. I've run an eigenmode analysis according to the given linear elastic example on my mesh with the stiffness matrix applied, and the results seem to agree with measured data, but I'm not certain how to extend this analysis to the multiphysics problem. I've tried driving the element with a periodic boundary condition, but I couldn't see any variation in the response vs. frequency--at least when looking at the maximum stress/strain at each frequency. Here are the equations--a slight modification of the given multiphysics example: equations = { '1' : """dw_volume_dot.i.volume(resonator.density, vv, dv/dt) + dw_lin_elastic.i.volume(resonator.D, w, u) - dw_piezo_coupling.i.volume(resonator.coupling, w, phi) = 0""", '2' : """dw_piezo_coupling.i.volume(resonator.coupling, u, psi) + dw_diffusion.i.volume(resonator.dielectric, psi, phi) = 0""", '3' : """dw_volume_dot.i.volume(resonator.density, w, du/dt) = dw_volume_dot.i.volume(resonator.density, vv, v)""" } I thought that perhaps the problem was the lack of a second order time derivative term, which is the reason for the third equation, but adding it didn't seem to help. I've noticed that the linear elastic terms don't seem to oscillate when stretched and released, perhaps this is at the root of the problem? or perhaps I'm mistaken in what I expect to see... Any help regarding piezoelectric modelling or harmonic oscillation would be appreciated. Thanks! Nolan

2 1

appveyor CI
by Robert Cimrman 09 Nov '16

09 Nov '16

Hi all, is there anybody here with some experience with setting up [1]? AppVeyor.com is a Continuous Integration service to build and run tests under Windows? See also [2]. Any help would be appreciated! r. [1] https://www.appveyor.com/ [2] https://github.com/sfepy/sfepy/issues/350

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SfePy November 2016