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No offence but people comes from many corners in the world... do u think everyone understand French...

I am so sorry....I should write in english...

So my problem is: I had some problem when I tried to solve a problem on a structure I created because the results were not coherent. So I concluded that the problem comes from the meshing. I decided to do a symmetrical meshing, but this function doesn't exist in Comsol. So I export the mesh to file .mphtxt in order to change the data to have a symmetrical meshing. I just arrived to change the coordinates of the nodes because I have some difficulties to understand what do the other parameters mean. I tried with a simple structure, but I didn't manage to understand the parameters of the .mphtxt file.
Futhermore, I don't know how to import the new meshing to Comsol. With Comsol script or with the interface, it's impossible to load two files which correspond to two parts of the structure.
Can you help me ? Do you have informations about the parameters of the .mphtxt file ? Do you know how to create a symmetrical meshing easilly ?

Thanks in adavance, and sorry for the first french message.

Pierre-Marie

what do you mean by symmetrical meshing? Can you show a schematic?

Bonsoir

c'est vrai que Comsol désire que nous conversions en anglais pour toucher plus de monde.

Well I have often the same issue, how to make symmetric/mirror meshes, I have sent this in to "support" a couple of times but they beleive I'm the only one so pls inform support too, if we are several to ask, they will implement it for us.

My way (and I have explaine it a couple of times in other threads too) is that I cut my volumes along symmetry planes, and I subdivide my volume into "splitted" volumes (via my CAD SolidWorks) so that I can better control locally the meshings. Then I use extensively copy paste mesh from surfaces of same topology, before I mesh the solid. The basic idea for subdividing the volume is to separate regions where I know I have high stress gradients (for structural) to allow for very fine mesh in these regions, and then have a rather coarse mesh elsewhere. This takes time (will be better in V4 where this sequence is stored to be replayd again later) but it works, even for complex true world (not academic cubes ;) cases.

The main reason why I need to use a full geometry (and cannot use "simple" symmetry boundaries) is that my loads are truely asssymetric and often time dependent or non-linear, or that I'm using local symmetries for a global assymetric volume, and we do not (yet?) have "superelements" in Comsol

The main drawback is the time to set it all up, and the extra internal boundaries, but often I can use these boundaries also as metrology points/eges/surfaces for the analysis of the results, and the extra computing load have been, in my cases, always shown to be negligible.

I must admit I have given up the task to write it out from the geometrical files, then you have the issue to set up the boundary conditions on the geoemtry recreated by Comsol from the mesh, you need to redefine these BC's each time you remesh, in Comsol, from my understanding BC's are attached to the "analysed geoemtry", and not directly on the mesh

Hope this helps on the way
Ivar

Thanks Ivar for your answer.
However, I already tried to cut my volume along symmetry planes in order to control the mesh in these litttle parts, and the result is not what I want. Furthermore, some time, Comsol doesn't want to copy the mesh from a little part to another one, an error appears.
For example, if you take a circle, and cut it in sectors, I want to do a symmetrycal mashing of one sector to another one, according to the center of the circle.
Have you already use the mesh export function, in order to create, by script, your own meshing ?

Thanks again,

Pierre

Hi

no I have not really exported meshes, imported yes. For the copy mesh the topology/shapes must be identical. I have just had a couple of exchanges with support on this issue, they have promished improvements in V4, and further mirror mesh features in next release thereafter, hope they will manage.

My best advise is to then mesh edges before surfaces (and copy surfaces so far as possible, and finally the volumes

Good luck
Ivar

Thanks a lot, I will try again to copy mesh.
Another question: When you have imported meshes, do you think is it possible to to import two files or more, one for each parts of the structure, or all the mesh of the structure has to be in the same file ?
Thanks again,

Pierre

Hi

indeed there seem to be some restriction when importing several meshes, separately, I havnt fully understtod why, but I have also decided not to investigate, as I'm waiting for th V4 revolution that will I'm sure change drastically the way to operate.
Ivar

It's ok, thanks for your help.

Pierre