Piezoelectric FEM

Hi everyone,

I have been asked to investigate replacements for the current FEM package we use (Ansys), promarily due to the fact that they have doubled their price this year.

I made a lot of noise saying \"Isn't there an open source alternative\", and therefore got given a bit of time to look for one. Paying for commercial support is not a problem.

The question:
Is one able to do Piezoelectric simulations in CAELinux? If not then are there other programs with support for Piezoelectric materials?

I'm downloading CAELinux, looks like a great effort, I'm sure it is warmly welcomed by many an engineer!

Regards,

Simon

Hi Simon,

To my knowledge, there is no piezoelectric model in Code-Aster (the main FE solver in CAELinux), but depending on the type of piezoelectric simulation that you need to do, a simple thermal expansion analogy can be used: this can be done only if you impose the electrical potential (typical case of an actuator), but it is not valid in the case of closed loop / fully coupled piezo-electric study (active damping ...)

I don't know if other general open source FE codes are more suitable for these kind of modelling, but you can find some piezo elements in ModuleF (a rather old french FE code) and maybe also in it's more recent derivative OpenFEM (matlab FE toolbox, LGPL, maintained by SDTools).

Thank you very much for your interest in CAELinux & i hope these informations will be usefull.

Hi,

This question is very rudimentary: how can we add functionality at element level?

I think that the Code-Aster development team has to answer to this.

The sure way is that you dive into the source code of the element that you want to use.(freely available on their website but you have to be fluent in french)

I'm a mechanical engineer and I want to ad a self regulating heater, I know I can introduce a thermal flux but here the flux is dependent from the temperature. This means that I have to couple a formula in the load that contains the temperature, which is a result. This may not be a problem as it is a solver and formulas can be used.

As I'm an engineer in mechanics I'm good in CAD/CAM/CAE but not in C, C++, Fortran, ...
I've had serious problems compiling Code-Aster in Fedora, I succeeded and the test calculations went OK but I did not succeed in creating a model in GMSH and feeding it to the solver so that I have a result. Each time I got errors back concerning the translating of the GMSH file in the solver.

When someone can give me a docuemnt that explains how to couple the load to the result I can translate it from french to english (and dutch).
If needed we could feed the necessary data and formulas to make it a realistic case.

Hi Gwen,

there is a simple solution for your needs, even without programming. You can define a non-linear, temperature dependant heat flux is Code-Aster in the following way:
1) create a function with DEFI_FONCTION to represent the heat flux / temperature relation. For this you will need to enter a set of points to define the curve (linear interpolation).
2) when you apply the thermal loads, use the AFFE_CHAR_THER_F command to specify a function-based non-linear heat flux with the FLUX-NL option (select the group of faces on which you want to apply the flux & the previously defined function).

And that's all !! it should work.

If you need more examples, decompress the astest.tar.bz2 archive in /opt/aster/STA8.1 and do some grep \"AFFE_CHAR_THER_F\" on the .comm files to see how to use this function.

For GMSH: there is a tutorial based on GMSH on Code-Aster website (I know it's in french, but the zip files contains the solution...) and I will try to add one example with GMSH in CAELinux.

Good luck