Mailman 3 - SfePy - python.org

Re: Problem(bug) with non-linear terms in library
by Robert Cimrman 20 Oct '23

20 Oct '23

Hi Himalaya Singh, The problem is that the initial T is zero, so having the conductivity equal to 2*T leads to a zero (singular) matrix and nothing can be computed. You seem to be setting the initial conditions correctly, but those are not used if pb.set_solver(nls) (nls = Newton solver) is used - you would need a time-stepping solver instead. Maybe you can just use 2*T+ "a small number" to make the problem regular? r. On 10/14/23 08:14, Himalaya singh wrote: > Hello, sfepy community > > I am new to this tool, and I have been exploring it for some time. I got > some issues related to Nonlinear diffusion's equation problem. > > It was working with 1+2*T**4 as in example however changing the non linear > term to 2*T is not working and tried other functions also. > > As I took 100mm*100mm domain and left boundary I fixed it to 25 degree > celsius(gamma1) and Right boundary(gamma2) as 500 degree celcius. > > Initial condition is taken as 25 degree celcius I took a nonlinear function > as 2T, I tried a lot, however the solution was reaching to infinity, I mean > it was showing (sfepy: linesearch: iter 2, (nan < nan) (new ls: > 1.000000e-01)). > > I attached the file below For Your Reference. > > Any lead or help will be highly appreciated Thank you for your help! > > > Himalaya singh > > Machine Design Department > > IIT Madras >

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Fwd: Problem(bug) with non-linear terms in library
by Robert Cimrman 13 Oct '23

13 Oct '23

Forwarding your message to the mailing list... Hello, Can you send us also the mesh, so that the example can be executed? In jupyter, you can (under File/Download as menus) download the notebook as a Python script and send that script - it is easier for me to run and more light-weight. r. -------- Forwarded Message -------- Subject: Problem(bug) with non-linear terms in library Date: Thu, 12 Oct 2023 15:19:14 +0530 From: Himalaya singh <aayusingh05(a)gmail.com> Hello, sfepy community I am new to this tool, and I have been exploring it for some time. I got some issues related to Nonlinear diffusion's equation problem. As I took 100mm*100mm domain and left boundary I fixed it to 25 degree celsius(gamma1) and Right boundary(gamma2) as 500 degree celcius. Initial condition is taken as 25 degree celcius I took a nonlinear function as 2T, I tried a lot, however the solution was reaching to infinity, I mean it was showing (sfepy: linesearch: iter 2, (nan < nan) (new ls: 1.000000e-01)). I attached the file below For Your Reference. Any lead or help will be highly appreciated Thank you for your help! Himalaya Singh Machine Design Department of Mechanical Engineering, IIT Madras

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sfepy new update 2023.3 (Not able to install in windows)
by Himalaya singh 04 Oct '23

04 Oct '23

Good Evening, My name is Himalaya Singh. I tried multiple times to update as well as to install new version of Sfepy, i didnot succeded. All the time it is showing error. I tried a lot, the same command in sfepy manual. I also look to dependencies and installed but still it was failing multiple times. Any help from your side will be helpful and appericiated. Thanks. Error message: error: subprocess-exited-with-error × Building wheel for sfepy (pyproject.toml) did not run successfully. │ exit code: 1 ╰─> See above for output. note: This error originates from a subprocess, and is likely not a problem with pip. Building wheel for sfepy (pyproject.toml) ... error ERROR: Failed building wheel for sfepy Failed to build sfepy ERROR: Could not build wheels for sfepy, which is required to install pyproject.toml-based projects

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Re: Terms are yet not working after updation also
by Robert Cimrman 01 Oct '23

01 Oct '23

Hello, On 9/30/23 10:27, Himalaya singh wrote: > Hello, sfepy community > > I am new to this tool, and I have been exploring it for some time. I got > some issues related to Non-linear poisson's equation problem,How to solve > the Non-linear PDEs problem in sfepy. > > In the previous mail I asked about examples of nonlinear PDEs that I got, > however the terms are not showing defined in the library (from sfepy.terms > import Term), I attached the file below. The terms should be there - are you sure you are using the latest release or git version? However, when I run your example, there is another problem. The equations cannot be created because the functions get_conductivity() etc. are only defined declaratively, and are not passed to the terms. I have noticed that the example `sfepy/examples/diffusion/poisson_nonlinear_material.py` is a bit misleading, because the `functions = ...` declaration has no effect there. I am attaching a slightly modified notebook that works for me. r.

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ANN: SfePy 2023.3
by Robert Cimrman 29 Sep '23

29 Sep '23

I am pleased to announce the release of SfePy 2023.3. Description ----------- SfePy (simple finite elements in Python) is a software for solving systems of coupled partial differential equations by finite element methods. It is distributed under the new BSD license. Home page: https://sfepy.org Mailing list: https://mail.python.org/mm3/mailman3/lists/sfepy.python.org/ Git (source) repository, issue tracker: https://github.com/sfepy/sfepy Highlights of this release -------------------------- - example demonstrating nonlinear diffusion and volume forces terms - new sensitivity term - proof-of-concept JAX-based auto-differentiable terms (elasticity, mass) + elastodynamics parameter identification example For full release notes see [1]. Cheers, Robert Cimrman [1] http://docs.sfepy.org/doc/release_notes.html#id1 --- Contributors to this release in alphabetical order: Robert Cimrman Giuseppe Colletta Lubos Kejzlar Vladimir Lukes Yosef Meller Oliver Stueker

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Non-linear Diffusion terms is not yet updated in terms library
by Himalaya singh 21 Sep '23

21 Sep '23

Hi, My name is Himalaya Singh. As i emailed earlier about the same, still it is not in working phase. so i request to update the terms library. Thanks

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time-dependent problem in sfepy
by Deepak Pawar 12 Jul '23

12 Jul '23

Hello, sfepy community I am new to this tool, and I have been exploring it for some time. I got some issues related to time-dependent problem How to solve the time-dependent second order differential equation problem in sfepy. Are there any solved examples related to the same? Any lead or help will be highly appreciated Thank you for your help! : -- *Regards* Deepak K Pawar Research Scholar Department of Mechanical Engineering IIT Madras, Chennai, India Mob No: +91-7208385265

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Non linear material
by J. Sanz 12 Jul '23

12 Jul '23

Hello, I have a problem with a simulation including non lineal material.The problem involves a cantilever beam. The free end is moved 20 mm in X direction. I have compared the results with Ansys. The stresses are different, in particular at the pastification zone. Yield point of the material Relastic = 130 MPa, Epsilon elastic =0.00173 The material is bilinear, it has two slopes, young 1 and young2. The slope changes in the yield point. The no linear material function is based on calculating the strains in every cell. It is assigned the second young modulus for those strains higher than epsilon elastic. If lower, first young modulus is set. You can find attached the files and comparison. The picture with the comparison has the same scale, so the colours represent the same stress range. My doubts are the next: 1-I am not sure if the material definition is right. Can you confirm this for me? 2-Order of the stress strain evaluation, I set it to 3 because it provides the closest results. 3-The output file .vtk contains only nodal solution. How to get the elemental solution as well? Thanks, Jesus Sanz

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ANN: SfePy 2023.2
by Robert Cimrman 29 Jun '23

29 Jun '23

I am pleased to announce the release of SfePy 2023.2. Description ----------- SfePy (simple finite elements in Python) is a software for solving systems of coupled partial differential equations by finite element methods. It is distributed under the new BSD license. Home page: https://sfepy.org Mailing list: https://mail.python.org/mm3/mailman3/lists/sfepy.python.org/ Git (source) repository, issue tracker: https://github.com/sfepy/sfepy Highlights of this release -------------------------- - replace numpy.distutils by scikit-build (cmake) - interface for the PRIMME eigenvalue problem solver - new declarative modal analysis example - new terms: nonlinear diffusion and nonlinear volume forces For full release notes see [1]. Cheers, Robert Cimrman [1] http://docs.sfepy.org/doc/release_notes.html#id1 --- Contributors to this release in alphabetical order: Robert Cimrman Giuseppe Colletta Vladimir Lukes Yosef Meller

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Calculating strains from given nodal displacements
by Sebastian Bachmann 26 Jun '23

26 Jun '23

Hi! I have a tetrahedral mesh and know the nodal displacements of the mesh from an external software. I now want to calculate the element' strains and thought I give sfepy a go. However, the learning curve is very steep and I struggle a bit with this - I thought - easy task. I thought I basically need this function here: https://sfepy.org/doc-devel/primer.html#post-processing but how do I initially setup the problem and set the already solved displacement vector? This is what I got so far: ``` import numpy as np from sfepy.discrete.fem import Mesh, FEDomain from sfepy.discrete import Problem # Given: mesh and nodal displacements mesh = Mesh.from_file('the_mesh.vtk') u_vec = np.random.random((mesh.n_nod, 3)) # here I would insert the actual displacements. Use random numbers for testing domain = FEDomain('domain', mesh) omega = domain.create_region('Omega', 'all') # ??? pb = Problem('elasticity', domain=domain, ...) # ??? # ??? strain = pb.evaluate('ev_cauchy_strain.2.Omega(u)', mode='el_avg') ``` Am I on the right track here? Thanks in advance! Best, Sebastian

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