Mailman 3 - SfePy - python.org

conversion formulas of elastic constants
by Robert Cimrman 14 Apr '10

14 Apr '10

Hi, you can test ([0]) a new ElasticConstants class [1] that implements all possible conversion formulas for: Young’s modulus Poisson’s ratio bulk modulus Lamé’s first parameter shear modulus = Lamé’s second parameter P-wave modulus = longitudinal wave modulus Given any two constants, it can determine the remaining, see [2], [3]. Basically, at [2] there are all the formulas without the P-wave modulus, while at [3] there are all the constants, but not all the formulas (60 for six constants). It uses sympy to some extent for the moment, but later we could just use the resulting relations converted to Python functions. Let me know if it works for you or not. thanks, r. [0] http://github.com/rc/sfepy [1] http://docs.sfepy.org/doc-devel/src/sfepy/mechanics/matcoefs.html [2] http://www.efunda.com/formulae/solid_mechanics/mat_mechanics/calc_elastic_c… [3] http://en.wikipedia.org/wiki/Lam%C3%A9_parameters

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closing issues
by Robert Cimrman 13 Apr '10

13 Apr '10

Hi (Andre), shall we close issues 110, 111? The changes are already in the master repo. What about 116 - are you satisfied with the answer? r.

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Probing data
by freevryheid 12 Apr '10

12 Apr '10

I see some probing functions in the code although no examples or documentation. Is this still under development? I'm looking for a way to extract info from the results file.

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scipy 2010 conference
by freevryheid 12 Apr '10

12 Apr '10

Any plans to present info on Spefy at the scipy conference this year? https://conference.scipy.org/scipy2010/index.html

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Access to discretized problem
by Dominique 08 Apr '10

08 Apr '10

Hello, I am considering using SfePy for some test problems. I am wondering if SfePy will grant me access to the discretized problem. More precisely, if a set of PDEs is discretized over a given domain to yield a system of nonlinear equations, say F(x)=b, it is possible/easy to evaluate F(x) and its Jacobian F'(x) from my own code? On a similar topic, I presume it is sufficient to specify a value for the 'lin_solver' argument to a NonlinearSolver instance to "plug in" different linear system solvers to solve F(x)=b?! In order to make an educated choice, I would like to access and see the structure of the linear systems. Is there an example showing how this can be done? Finally, since SfePy allows for the solution of Stokes problems, I presume it is possible to obtain a mixed FEM discretization for a given set of PDEs? Thanks in advance! Dominique

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docs broken
by Andre Smit 06 Apr '10

06 Apr '10

Cannot open the following page: http://docs.sfepy.org/doc/src/sfepy/mechanics/matcoefs.html When: 05 Apr 2010, 3:30 PM, USA Central Time

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2D integral
by freevryheid 04 Apr '10

04 Apr '10

I've a 2D model with triangle elements. I'm confused regarding the order and integral type - I can't use gauss_o1_d2 so I tried gauss_o2_d2 and gauss_o3_d2, which work fine i.e. displacements look realistic. I'm confused why these would be 'volume' integrals when I'm using a 2D surface. The code as applied follows: #! Fields #! ------ #! A field is used to define the approximation on a (sub)domain #! A displacement field (three DOFs/node) will be computed on a region #! called 'Omega' using P1 (3-node triangle) finite elements. fields = { 'displacement': ((2,1), 'real', 'Omega', {'Omega' : '2_3_P1'}), } #! Integrals #! --------- #! Define the integral type Volume/Surface and quadrature rule #! (here: dim=2, order=3). integrals = { 'i1' : ('v', 'gauss_o3_d2'), } Andre Smit

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Stress strain calculations
by freevryheid 03 Apr '10

03 Apr '10

Hey guys First off let me congratulate you on an excellent FEM application. The more I get into it, the more I appreciate the volume of work that has gone into it :) I particularly like the way a problem is defined using python. I've never come across anything else that allows such a simple yet powerful definition. I understand that the app is still under development and that the documentation is lacking. My experience with FEM software has mostly been "blackboxed" using ABAQUS, etc. My lack of knowledge on the (weak) formulation of a problem is severely restricting my application of SfePy. For example, I have not been able to figure out how to output stresses and strains in the model using linear elastic analysis - the example provided only outputs displacements. Can someone please point me in the right direction. Regards Andre Smit

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runTests fails on ubuntu karmic x86
by freevryheid 02 Apr '10

02 Apr '10

fails 1/60 tests: here's the debug output grassy@work:~/sfepy./runTests.py --debug tests/ test_input_linear_elastic_mM.py <<< directory: tests, test files: 1 <<< tests/test_input_linear_elastic_mM.py sfepy: left over: ['__builtins__', '_filename', '__file__', '__package__', 'TestInput', 'input_name', '__name__', 'output_name', '__doc__'] --- test instance creation failed Traceback (most recent call last): File "./runTests.py", line 225, in <module> main() File "./runTests.py", line 216, in main run_tests(stats, dirname, [filename]) File "./runTests.py", line 148, in run_tests n_fail, n_total, test_time = run_test( conf_name, options ) File "./runTests.py", line 95, in run_test test = conf.funmod.Test.from_conf( conf, options ) File "tests/testsBasic.py", line 21, in from_conf test_conf = ProblemConf.from_file( input_name, required, other ) File "/home/grassy/sfepy/sfepy/base/conf.py", line 239, in from_file funmod = import_file( filename ) File "/home/grassy/sfepy/sfepy/base/base.py", line 86, in import_file mod = __import__(name) File "tests/../examples/homogenization/linear_elastic_mM.py", line 4, in <module> from sfepy.homogenization.micmac import get_homog_coefs_linear File "/home/grassy/sfepy/sfepy/homogenization/micmac.py", line 6, in <module> import tables as pt File "/usr/lib/python2.6/dist-packages/tables/__init__.py", line 76, in <module> from tables.file import File, openFile, copyFile File "/usr/lib/python2.6/dist-packages/tables/file.py", line 44, in <module> from tables import hdf5Extension ImportError: cannot import name hdf5Extension perhaps cython related?

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examples (wiki)
by Robert Cimrman 01 Apr '10

01 Apr '10

Hi all, The examples at [1] are very old (*) and not very well formatted. Has anyone something nice and interesting to replace them? The site [1] should contain preferably examples from sfepy users (if such a beast really exists), as the work of the team I am in is presented at [2]. I would like to move the old examples to an OldExamples wiki page for the record. r. (*) 14 test file(s) executed in 13.51 s, 0 failure(s) of 18 test(s) - now it's 59 tests [1] http://code.google.com/p/sfepy/wiki/Examples [2] http://sfepy.kme.zcu.cz/

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