Mailman 3 January 2017 - SfePy

Material Parameters of Individual Nodes
by derj...＠web.de 12 Apr '22

12 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.

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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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Type Error running examples
by Christopher Jones 02 Feb '17

02 Feb '17

I am getting the following error while trying to run 'its2d_interactive.py'. C:\Python36\Lib\site-packages\sfepy\linalg>python C:\Python36\Lib\site-packages\sfepy\examples\linear_elasticity\its2D_interactive.py Traceback (most recent call last): File "C:\Python36\Lib\site-packages\sfepy\examples\linear_elasticity\its2D_interactive.py", line 51, in <module> from examples.linear_elasticity.its2D_2 import stress_strain ModuleNotFoundError: No module named 'examples' I have been getting this error when ever I try to run examples. I tried changing the forward slashes to back slashes with no effect. I installed most of the dependencies from PIP, and installed a pre-built binary from Gohlke's LFD python libs page. I've tried running from the console as seen in the above error. I've also tried running from IDLE, for python 3.6. ANd I get no error messages from the IDLE console but also, I get no output file. I'm running IDLE with elevated privelage and I created the output directory inside the sfepy install directory, i.e. C:\Python36\Lib\site-packages\sfepy\examples\results... Ok, I see this error. I was not in the sfepy base directory. I changed this and got output in the console with the following error: C:\Python36\Lib\site-packages\sfepy>python C:\Python36\Lib\site-packages\sfepy\examples\linear_elasticity\its2D_interactive.py sfepy: using values: sfepy: Young's modulus: 2000.0 sfepy: Poisson's ratio: 0.4 sfepy: vertical load: -1000.0 sfepy: uniform mesh refinement level: 0 sfepy: reading mesh [line2, tri3, quad4, tetra4, hexa8] (C:\Python36\lib\site-packages\sfepy/meshes/2d/its2D.mesh)... sfepy: ...done in 0.00 s Traceback (most recent call last): File "C:\Python36\Lib\site-packages\sfepy\examples\linear_elasticity\its2D_interactive.py", line 293, in <module> main() File "C:\Python36\Lib\site-packages\sfepy\examples\linear_elasticity\its2D_interactive.py", line 175, in main domain = FEDomain('domain', mesh) File "C:\Python36\lib\site-packages\sfepy\discrete\fem\domain.py", line 50, in __init__ gel.poly_space = PolySpace.any_from_args(key, gel, 1) File "C:\Python36\lib\site-packages\sfepy\discrete\fem\poly_spaces.py", line 272, in any_from_args return table[key](name, geometry, order) File "C:\Python36\lib\site-packages\sfepy\discrete\fem\poly_spaces.py", line 444, in __init__ self.nodes, self.nts, node_coors = self._define_nodes() File "C:\Python36\lib\site-packages\sfepy\discrete\fem\poly_spaces.py", line 465, in _define_nodes nodes = nm.zeros((n_nod, n_v), nm.int32) TypeError: 'float' object cannot be interpreted as an integer Any ideas? Thanks, Chris

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BC using dw_surface_flux not being met?
by David Jessop 11 Jan '17

11 Jan '17

Hi, I need to set insulated boundaries on two edges of my problem, and set the flux on a third. I've specified material properties (2D problem) as ins = Material('ins', val=[[0.0, 0.0], [0.0, 0.0]]) flux = Material('flux', val=[[-1.0, 0.0], [0.0, -1.0]]) and then I write my BCs as tSurfInsT = Term.new('dw_surface_flux(ins.val, u, v)', integral, Top, ins= ins, u=u, v=v) tSurfInsL = Term.new('dw_surface_flux(ins.val, u, v)', integral, Left, ins= ins, u=u, v=v) tSurfFluxR = Term.new('dw_surface_flux(flux.val, u, v)', integral, Right, flux=flux, u=u, v=v) As you might infer from the visualisation of the solution below, thes BCs are not being met (slope of the contours should be flat on the LHS and not flat on the right). Indeed, if I comment these out of the equation definition, the solution remains unchanged. What is going on? Thanks, David <https://lh3.googleusercontent.com/-cTRMmEvK4b0/WGy-o0MCHaI/AAAAAAAAA8s/F0T6…>

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Help in defining a contact problem for multiple bodies
by samyak jain 11 Jan '17

11 Jan '17

Hello everyone, I am new to Sfepy and to Finite Element Analysis. I am currently trying to solve a contact problem between two bodies to the find the displacement and the stress. The first body is a hemisphere (could be other shape-later on) and the second body is any free-form shape. The second body is fixed and there is a specified displacement boundary condition on the first body. That is all regarding the problem definition and the boundary conditions. I have seen few examples in the gallery section sfepy website and I found an example of Contact Sphere, Contact plane and an example with displacement boundary condition. But in all these examples, there is always one mesh and consequently one domain where we can define our boundary regions and solve the PDE. But in my case, I have two mesh as I cannot combine them. If I can combine them as one mesh, I can solve the problem but I cannot do that. So, how would I progress with this problem. I have two mesh, so I will have two different domain and them use it to define regions. Now the problem arises where should I define the field variable. What I understand that there will be two different field variable based on two domain but I am not sure how to use sfepy to solve such a problem. Could someone please guide me by an example of such a case where contact between multiple bodies is done with multiple mesh being used. I have tried and I am unable to come up with a proper way to use sfepy with this problem. Thanks a lot. Samyak

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one problem in ''biot.py"
by Kid Guo 10 Jan '17

10 Jan '17

Hi, I have a problem based on "../sfepy/examples/multi_physics/biot.py". In the attached scripy 'block2.py', I have calculated the stress and strain according to the displacement, at the 111 and 112 lines you can see it. Now I want to output the K of every cell, I gave a value of k at the 64 line in this script, it is a 3*3 array. I don't know which function or equation to use, so I was stucked at the 113 line. if I change the K value, will where be some difference results? Thank you advance K.

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Surface normal
by Nikhil Vaidya 10 Jan '17

10 Jan '17

Hello, I have a question regarding the surface normal vector when using the term: dw_surface_flux In my problem, I have an interface between two materials. For each material, the weak form contains the above term. Now, I have defined the interface as a facet region, and I pass this to the term in both equations. I think that the normal vector for the surface in the respective materials is not defined. How can I define this? Best regards, Nikhil

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Error in calculating cauchy stress. Wrong arguments shape
by samyak jain 09 Jan '17

09 Jan '17

Hi all. I keep getting this error with the latest version of sfepy when I run the following lines. Could you guys please help. strain = pb.evaluate('ev_cauchy_strain.{dim}.Omega(u)'.format(dim=dims), mode='el_avg') The above line works fine. stress = pb.evaluate('ev_cauchy_stress.3.Omega(m.D, u)', copy_materials=False, mode='el_avg') but the stress line always shows the error below. m is defined before in the problem with 'D' value. File "C:\Python27\lib\site-packages\sfepy\discrete\problem.py", line 1264, in evaluate sfepy: allowed argument shapes for term "ev_cauchy_stress.3.Omega(m.D, u)": sfepy: [{'material': 'S, S', 'parameter': 'D'}] mode=mode, dw_mode=dw_mode, term_mode=term_mode) File "C:\Python27\lib\site-packages\sfepy\discrete\evaluate.py", line 280, in eval_equations term_mode=term_mode, asm_obj=asm_obj) File "C:\Python27\lib\site-packages\sfepy\discrete\equations.py", line 621, in evaluate term_mode=term_mode) File "C:\Python27\lib\site-packages\sfepy\discrete\equations.py", line 817, in evaluate ret_status=True) File "C:\Python27\lib\site-packages\sfepy\terms\terms.py", line 1337, in evaluate self.check_shapes(*args) File "C:\Python27\lib\site-packages\sfepy\terms\terms.py", line 1215, in check_shapes % term_str) ValueError: wrong arguments shapes for "ev_cauchy_stress.3.Omega(m.D, u)" term! (see above)

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