Discussion Forum

Posted: 1 decade ago 09.05.2011, 14:49 GMT-4

Hi have you checked if ther are small features you do not really see, silver spikes, short edges etc (or holes) Anoter way is to see if you an import your file into a true 3D cad modeller as SolidWorks, Pro-E or inventor, as closed geometry -- Good luck Ivar

Posted: 1 decade ago 09.05.2011, 15:19 GMT-4

Hi, I am having similar issues, I create 3D geometries in Inventor uniting together several surfaces so that Inventor itself sees one unique surface; however, whenever I export it as a .sat, .stp or even binary file for Parasolid and then I import it in Comsol I see again all those surfaces that are not supposed to be there. What type of geometry are you actually building? Volumes? Do you fuse surfaces together to yield a volume? Regarding the meshing error, I got errors after importing only when I imported threaded holes or similar. I resolved the problem (thanks to support) with the mesher of the 3.5 version. Cheers

Posted: 1 decade ago 09.05.2011, 17:12 GMT-4

Hi from my understanding, for 3D we sould use correctly bounded volumes (from a CAD system) in 2D it's planar surfaces, something not always that easy to generate, depending on the SW. I generally export a plane cut view from SW to get a surface, and then export it as DXF. It mostly works -- Good luck Ivar

Posted: 1 decade ago 10.05.2011, 09:33 GMT-4

[QUOTE] Hi, I am having similar issues, I create 3D geometries in Inventor uniting together several surfaces so that Inventor itself sees one unique surface; however, whenever I export it as a .sat, .stp or even binary file for Parasolid and then I import it in Comsol I see again all those surfaces that are not supposed to be there. What type of geometry are you actually building? Volumes? Do you fuse surfaces together to yield a volume? Regarding the meshing error, I got errors after importing only when I imported threaded holes or similar. I resolved the problem (thanks to support) with the mesher of the 3.5 version. Cheers [/QUOTE] For some parts I am extruding surfaces to solids, and for some parts I am building solids out of intersecting surfaces. All in all, it is a kind of a box structure with a hole on one side. I started importing it to Comsol part by part, and as soon as I have top and bottom plate and two sides, the meshing fails. How did you exactly resolve this meshing problem? I am actually using 4.0a instead of 3.5. Regarding the small details, I have tried the repair function in Comsol. I will definitely check the spikes, but I have been very careful in building my geometry in Rhino. What I don't get is the reason why the union works in Rhino, but not in Comsol.. Thanks, Henna

Posted: 1 decade ago 10.05.2011, 11:43 GMT-4

Hi, It seems relatively similar to some imports I had, but I am not sure I understand why do you import part by part? Can't you complete your design in Rhino and then export it? I usually complete the geometry in Inventor then export it as a .x_t or .x_b or .stp or whatever into Comsol, then I do have several problems if the original geometry is too complex, I have not found a way to let Comsol digest my complicated geometries yet (I am woking with 4.1.0.185). When the geometry is very complicated like in the case of a screw-hole I had support to mesh it for me with the mesher from 3.5... Regarding the repair features... well if I import anything from Inventor they don't seem to be that beneficial or to have any effect... Cheers

Posted: 1 decade ago 10.05.2011, 13:39 GMT-4

Hi my advise (i have posted several comments already, and that applies for 3.5 as for 4) is to cut up your complex models into several domains/geometrical objects. Even if this adds interior boundaries, it helps the mesher, try to avoid parts with long loops (doughnut or torus shapes), cut them in the middle or in 4 to "open" the loop, and not to mesh it in one go. then mesh from inside and out, minimise parts meshed at the end with all surrounded boundaries already meshed play with the mesh density, add seed mesh along edges, specially in the region of small features, or where you mesher reports difficulties -- Good luck Ivar

Posted: 1 decade ago 10.05.2011, 16:44 GMT-4

Hi, Thanks for the advice but I am afraid is quite hands-off. My geometries are relatively simple, however they need some extruding and revolving and those operations cause several surfaces to appear and there is no way to unify them together neither with comsol nor with inventor. Subdomains did not change much, because each subdomain presents those very surfaces which then in turn cause so many problems while meshing. At any rate I am waiting for some answer from support. Cheers

Posted: 1 decade ago 10.05.2011, 17:01 GMT-4

Hi well then we must have been lucky, because so far we mostly manage to mesh directly, even our most complex geometries (>1000 COMSOL objects, or assemblies of several hundred Solidworks parts). I must admit mostly in manual mode, but without big hassles Then I'm mostly working in dynamic models of solid + thermo-elasticity and ACDC or RF, but with size ratios in the 1:>>10'000 so its not always that different from CFD meshing issues -- Good luck Ivar

Posted: 1 decade ago 11.05.2011, 02:08 GMT-4

Hi, That is extremely interesting, because you tell me that you use Solidworks (and it is the same kernel for Comsol) but I do not have Solidworks, I have Inventor... One more example: I have a 3D plate with screw-holes and other stuff on it, no matter what I do in Inventor and no matter whether I export it as .igs, .stp or anything else, Comsol transorfms my 3D plate into a surface... I am waiting an answer from support but I am afraid it has something to do with Inventor and not Comsol... Cheers

Posted: 1 decade ago 25.11.2013, 23:12 GMT-5

Hey, I have searched about this issue may be this works in solidworks perfectly, I found this solution from http://www.techmaish.com/how-3d-animation-is-different-from-2d-animation/