Mailman 3 July 2017 - SfePy

Material Parameters of Individual Nodes
by derj...＠web.de April 12, 2022

April 12, 2022

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

3 5

Calculate total force from cauchy stress
by Patricia Garcia Cañadilla Jan. 17, 2019

Jan. 17, 2019

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), }

4 5

Re: Torque
by Robert Cimrman March 9, 2018

March 9, 2018

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

acoustics and piezoelasticity example
by firdaus prabowo July 26, 2017

July 26, 2017

Hi Robert, Do you have any detail documentation which explains the examples here: http://sfepy.org/doc-devel/examples/acoustics/ and http://sfepy.org/doc-devel/examples/multi_physics/piezo_elasticity.html ? Starting from PDE to be solved if possible. Thanks. Regards, Firdays

3 2

order already used
by Yoni Teitelbaum July 24, 2017

July 24, 2017

Hi all, Problem description file and error output below. I don't understand what this error means or why I am getting it. At this point I'm still trying to learn my way around sfepy and I'm not 100% comfortable with the underlying math either. So this file might not make sense as far as what it appears to be trying to model, and my error could be in the code or in the math itself. I'm running the problem description file using simple.py from within a tmux session on Ubuntu 14.04 in anaconda. The anaconda environment uses python 2.7 so that mayavi will also work. Thanks in advance for any help. -Yoni Problem description: filename_mesh = sfepy_dir + '/meshes/2d/square_quad.mesh' regions = { 'Omega': 'all', 'Gamma_Top': ('vertices in (y == 0.4)', 'facet'), 'Gamma_Bottom': ('vertices in (y == -0.5)', 'facet'), 'Gamma_Left': ('vertices in (x == -0.5)', 'facet'), 'Gamma_Right': ('vertices in (x == 0.4)', 'facet') } fields = { 'head': ('real', 1, 'Omega', 1), 'reservoir_height': ('real', 1, 'Omega', 1) } variables = { 'u' : ('unknown field', 'head', 0, 1), 'l' : ('test field', 'head', 'u'), 'h' : ('unknown field', 'reservoir_height', 0, 1), 'l2' : ('test field', 'reservoir_height', 'h'), } ebcs = { 'u1' : ('Gamma_Left', {'u.0' : 2.0}), 'u2' : ('Gamma_Right', {'u.0' : -2.0}), 'u3' : ('Gamma_Top', {'u.0' : 5.0}), 'u4' : ('Gamma_Bottom', {'u.0' : 0.0}) } integrals = { 'i' : 2 } materials = { 'storativity' : ({'name': 'S', 'values': {'val' : 1.0}}), 'HParam': ({'name': 'hp', 'values': {'val' : 0.2}}) } equations = { 'diffusion' : """ dw_volume_dot.i.Omega(S.val, l, du/dt) = dw_electric_source.i.Omega(S.val, l2, h) """ } solvers = { 'ts' : ('ts.simple', { 't0' : 0.0, 't1' : 10.0, 'dt' : None, 'n_step' : 11, # Has precedence over dt. }), 'newton' : ('nls.newton', { 'i_max' : 1, 'eps_a' : 1e-10, }), 'ls' : ('ls.scipy_direct', {}), } Error: File "/home/yoni/anaconda3/envs/mayavi_env/lib/python2.7/site- packages/sfepy/script/simple.py", line 184, in <module> main() File "/home/yoni/anaconda3/envs/mayavi_env/lib/python2.7/site- packages/sfepy/script/simple.py", line 177, in main app = PDESolverApp(conf, options, output_prefix) File "/home/yoni/anaconda3/envs/mayavi_env/lib/python2.7/site- packages/sfepy/applications/pde_solver_app.py", line 137, in __init__ self.problem = Problem.from_conf(conf, init_equations=is_eqs, **kwargs) File "/home/yoni/anaconda3/envs/mayavi_env/lib/python2.7/site- packages/sfepy/discrete/problem.py", line 173, in from_conf obj.set_equations(conf.equations, user={'ts' : obj.ts}) File "/home/yoni/anaconda3/envs/mayavi_env/lib/python2.7/site- packages/sfepy/discrete/problem.py", line 464, in set_equations variables = Variables.from_conf(self.conf_variables, self.fields) File "/home/yoni/anaconda3/envs/mayavi_env/lib/python2.7/site- packages/sfepy/discrete/variables.py", line 156, in from_conf var = Variable.from_conf(key, val, fields) File "/home/yoni/anaconda3/envs/mayavi_env/lib/python2.7/site- packages/sfepy/discrete/variables.py", line 847, in from_conf special=special, key=key, history=history) File "/home/yoni/anaconda3/envs/mayavi_env/lib/python2.7/site- packages/sfepy/discrete/variables.py", line 1338, in __init__ special, flags, **kwargs) File "/home/yoni/anaconda3/envs/mayavi_env/lib/python2.7/site- packages/sfepy/discrete/variables.py", line 878, in __init__ self._set_kind(kind, order, primary_var_name, special=special) File "/home/yoni/anaconda3/envs/mayavi_env/lib/python2.7/site- packages/sfepy/discrete/variables.py", line 887, in _set_kind raise ValueError('order %d already used!' % order) ValueError: order 0 already used!

2 3

Postprocessing using mayavi for python 3
by firdaus prabowo July 14, 2017

July 14, 2017

Hi, It seems that postprocessing involving mayavi is not working in python 3.6, simply because mayavi so far only support python 2. Am I correct? Regards, Firdaus

2 8

Artifacts in solution after switch from tet to hex mesh?
by Jason Furtney July 11, 2017

July 11, 2017

Hello, Thank you to everyone for all the effort that has been put into SfePy, it is a pleasure to use. I am trying to solve a transient diffusion problem similar to the poisson_periodic_boundary_condition.py example but on a mesh of hexahedral elements. The example works well with the provided tet mesh. When I switch to a hex mesh the solution has some problems. The solution on gridpoints just outside the source region goes below zero at early times and the solution has some waves along line x=y=z. It seem like the elements may be read in wrong but I cannot figure out the problem. I create the hex mesh, test_hex.mesh, with this Python code: import numpy as np from sfepy.mesh.mesh_generators import gen_block_mesh from sfepy.discrete.fem.meshio import MeditMeshIO mesh = gen_block_mesh(np.array((10,10,1)), np.array((11,11,2)), np.array((5.0,5.0,0.5)), mat_id=9, verbose=True) m = MeditMeshIO("dummy_name") m.write("test_hex.mesh", mesh) The attached code is a simplification of the poisson_periodic_boundary_condition.py example, I removed the periodic boundary condition and the time-dependent material properties. with_tet_mesh.py gives good results and with_hex_mesh.py shows the problem. I am running Python 2.7.13 and SfePy version 2017.2; I get the same result from the current SfePy github master. I run the code with the command python simple.py with_hex_mesh.py. Can someone help me understand where I am going wrong? Thanks, Jason

3 2

Can't not find a relevant integration term
by nduyduc1989＠gmail.com July 10, 2017

July 10, 2017

Hi all I am new in sfepy and I have a simple question. I don't know which provided integration term is appropriate to compute the following formula: \int_{\Omega} u_1 * \grad(u_2) \cdot \grad(v) dx, where u_1 and u_2 are unknowns and v are test function. If you have any idea to solve this problem, please let me know. Thank you very much Best

2 1

Can't not find a relevant integration term
by nduyduc1989＠gmail.com July 10, 2017

July 10, 2017

Hi all I am new in sfepy and I have a simple question. I don't know which provided integration term is appropriate to compute the following formula: \int_{\Omega} u_1 * \grad(u_2) \cdot \grad(v) dx, where u_1 and u_2 are unknowns and v are test function. If you have any idea to solve this problem, please let me know. Thank you very much Best

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