Free Open Source FEM Softwares
Contents
Intro
This post shows a few interesting (and free) solutions structural engineers may find useful.
The common structural softwares for FEM analysis like Ansys, Abaqus, Nastran,etc.. have a license cost from 20′000 up to more than 100′000. If you are not a worker inside a great company or if you are not rich, you can not afford that.
Today on the web there are several free solutions, some of them have great potential, almost like commercial utilities. They are just a little harder to use, they are not the kind of user friendly softwares.
A complete list of the packages can be found here: http://en.wikipedia.org/wiki/List_of_finite_element_software_packages
A first attempt to link all fem free utilities into a single operating system has been made by J, Cugnoni with his Caelinux. Caelinux is an ubuntu linux version that contains many free fem utilities. Unfortunately the current version is the old ubuntu 9 and it can gives drivers issues with modern machines. Anyway all the packages in Caelinux can be installed on most linux platforms.
I report here my review about the 3 softwares that I consider a good trade-off between usability/perfomances and capabilities.
Code Aster
Code_Aster is an Open Source software package for Civil and Structural Engineering finite element analysis and numeric simulation in structural mechanics originally developed as an in-house application by the French company EDF. It was released as free software under the terms of the GNU General Public License, in October 2001.
Code aster can be compiled both on windows and linux, but since it can be integrated with the cad utility SALOME, it is better to use it on linux. A complete integrated package called SAlOME-MECA can be downloaded here: http://www.code-aster.org/V2/spip.php?article303
Code Aster is suitable for very complicated termo-mechanical analysis: it can take into account plasticity, non linear geometry, material state exchange, cracking and creep.
Unfortunately it take some time to learn how to use code aster. The solver takes as main input a python script that defines the kind of analysis , boundary conditions, time steps etc. To write this file is necessary a basic knowledge of FEM algorithms. A few samples for typical analysis are available on the web. The python library to write the input file is enormous and most of the doc is in french, this can be painful for someone. Two main utilities to simplify the Code_Aster input process are available: EFICAS that helps writing the input file and ASTK a job manager server.
ELMER
http://www.csc.fi/english/pages/elmer
Elmer is an open source multiphysical simulation software developed by CSC. Elmer development was started 1995 in collaboration with Finnish Universities, research institutes and industry.
Elmer includes physical models of fluid dynamics, structural mechanics, electromagnetics, heat transfer and acoustics, for example. These are described by partial differential equations which Elmer solves by the Finite Element Method (FEM)
Among the three elmer is simplest to use. A nice GUI guides the user trough all the fem model construction. It also has a mesh package even if it doesn’t allow for many editings. With elmer is just so easy to realize multiphisics anaisys. It also has a good built-in material library that turn out to be very useful. An interactive post-processing tools allows to visualize results.
Calculix
CalculiX is a package designed to solve field problems. The method used is the finite element method.
With CalculiX Finite Element Models can be build, calculated and post-processed. The pre- and post-processor is an interactive 3D-tool using the openGL API. The solver is able to do linear and non-linear calculations. Static, dynamic and thermal solutions are available. Both programs can be used independently. Because the solver makes use of the abaqus input format it is possible to use commercial pre-processors as well. In turn the pre-processor is able to write mesh related data for nastran, abaqus, ansys, code-aster and for the free-cfd codes duns, ISAAC and OpenFOAM. A vda CAD interface is available. The program is designed to run on Unix platforms like Linux and Irix computers but also on MS-Windows.
The CalculiX package was developed by a team of enthusiasts in their raw spare time. They are employees of MTU Munich, an Aero Engine manufacturer in Germany which granted the publication.
Calculix is made by two console applications: CCX which handles the computation and CGX which handles the graphical operations. Calculix offers steady and dynamics structural and fluid analysis and has one main peculiarity: it has the same Abaqus input file syntax.
More
Do you use others utilities that should be included in the above list? just tell us in the comments.
Popularity: 1% [?]
Quick Delaunay Triangulation
Filed under: Algorithms, C, Computational Geometry, FEM, Geometry
Contents
QuickDel
It has always been a dream of mine to code a Delaunay triangulator. Last week I had 3 free days and I did it. I actually thought it was more complicated, as it often happens, when you are outside the problem it seems bigger than it really is.
In this post you will find a Delaunay triangulation algorithm. My idea is to start a project which purpose is to create a robust an efficient triangulation/meshing tool.
The first release will be Delaunay triangulation function QuickDelMex
Below a comparison with DelaunayTri from the computational geometry toolbox.
Number of points QuickDel Built-in Matlab speed-up
10 0.0002 s 0.0142 98.69% s
100 0.0002 s 0.0094 97.61% s
1000 0.0016 s 0.0099 84.13% s
10000 0.0149 s 0.0707 78.96% s
100000 0.1856 s 1.2044 84.59% s
1000000 2.5094 s 14.1102 82.22% s
t=QuickDelMex(p) (version 0.3)
returns the Delaunay triangulation of the 2D point set p;
INPUT:
- * p: double array of size 2xN. The list of unique points [x1 y1,x2 y2];
OUTPUT:
- * t: double array of size ntx3. It contains the triangles of the Delaunay triangulation. Each rows contains 3 indexes of the points forming the triangle. Indexes are sorted counterclockwise; first points is flagged as one.
NOTES:
- * -This function is a prototype so don’t trust too much, please check the results and in case send bug report.
- * -This function is optimized for uniform random dataset, sparse datasets may slow down the algorithm.
- * -This function may not return the whole convex hull. Thin boundary triangles may be discarded.
- *- v0.3 is alittle slower but much more robust than v0.2.
Author: Luigi Giaccari (giaccariluigi@msn.com)
see also DelaunayTri delaunay delaunayn
Downloads
Matlab
You can download MEX Files of QuickDel here (win32 and linux):
A test to evaluate performances is also available on Matlab file exchange (Download Now)
C++
A Win32 executable is available here (v0.2):
it asks for the number of points to be triangulated. Once the triangulation has been done it prints a text file (a matlab m-file) which allows to visualize the triangulations inside Matlab.
I can also build a win32 .dll, but I was too lazy to do it, if you want it please contact me.
Acknowledgements
- This function uses the robust predicates from Jonathan Richard Shewchuk
Contacts
Please send bug reports/suggestions at: giaccariluigi@msn.com
This utility can be greatly enlarged, please compile the following survey.
Popularity: 2% [?]
The Nonlinear Finite Element Toolbox (NLFET)
NLFET is a nonlinear finite element toolbox for MATLAB released under the GNU General Public License (GPL). The toolbox provides a framework for setting up, solving, and interpreting results for nonlinear static and dynamic finite element analysis.
- Manual – A short overview of NLFET in PDF format.
- Download – The source code for the toolbox in tar gzip format (WinZip should be able to extract this).
- Single Bay Example – Example code using the single bay frame from “A Nonlinear Finite Element Toolbox for Structural Control” presented at the Third World Conference on Structural Control.
- util.tgz – Utility functions in tar gzip format that are necessary to get the toolbox to run and for the examples.
It is now possible to browse the CVS repository or access it using anonymous access.
Example code for a semiactive control system using MR dampers is also available. Please contact info@nlfet.org if interested.
If you would like to help in the development of NLFET, or if you have any questions, please contact matt@nlfet.org.
Popularity: 25% [?]
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