[ICEM] best method to generate surfaces from a .stl file format

snudurupati · July 21, 2009, 14:59

Hello

I have a MRI generated 3-d image in .stl format. I was able to create the surface from ICEM using the topology option but was wondering what is the best method to generate one surface from .stl ( hundereds of surfaces).

Is there a 3rd party software which can do good job or is ICEM the best now??

PSYMN · July 22, 2009, 12:27

If you can generate an ICEM CFD Hexa blocking for the model, ICEM CFD can convert that to bspline surfaces (look under File => Edit). The only downside is that you will have to block it out (at least a surface blocking) first, which isn't bad for arteries or bones, but could take a long time if you had a lung or a brain.

If it is somewhat regular, you could try FE Molder (Workbench) which is a more automatic way to get the job done, but often fails for highly irregular biomedical parts.

But there is a whole industry around surfacing faceted models; you could start with our sister company (now independent) ICEM Surf. This still requires effort, but since it is their focus, they should be pretty good at it.

I actually haven't needed to surface facets for quite a while because ICEM CFD is so good at meshing directly from the facets. You may want to ask yourself why you are surfacing. If it is for simulation, you can skip it and save a lot of time. If you want a CAD model for some other reason, check if your primary CAD package has anything that can help. Then try ICEM Surf.

snudurupati · July 23, 2009, 10:21

Thank you for your reply. That was really helpful for my understanding.

The geometry will be starting from simple structure to complex structures like valve mechanisms in the heart. Would the Hexa meshing be appropriate? I did not get a complete feel for the hexa mesh yet but I can see that it is very useful. But what are the limitation for Hexa mesh?? Is is the geometry?

I tried the FE Modeler, but it will not accept .stl format. Rather I can use 3-rd party software like Rhino to create Facets and then import as IGES to Modeler

Also right now i am concerned with only the simulation, but in the near future i will require the CAD model to convey other parameters like the non uniform wall thickness, hyperelasticity of the wall etc.

I will also look into ICEM Surf!! Do you happen to know if I can use a trial version for this software?? Right now I am confused as to which software to use which will be helpful in the long run i.e, when I encounter Complicated geometry and Moving Boundary and two way FSI.

July 21, 2009, 14:59	best method to generate surfaces from a .stl file format	#1
snudurupati New Member sai Join Date: Jun 2009 Location: New Jersey Posts: 9 Rep Power: 16	Hello I have a MRI generated 3-d image in .stl format. I was able to create the surface from ICEM using the topology option but was wondering what is the best method to generate one surface from .stl ( hundereds of surfaces). Is there a 3rd party software which can do good job or is ICEM the best now??

July 22, 2009, 12:27	Surfacing...	#2
PSYMN Senior Member Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,663 Blog Entries: 1 Rep Power: 47	If you can generate an ICEM CFD Hexa blocking for the model, ICEM CFD can convert that to bspline surfaces (look under File => Edit). The only downside is that you will have to block it out (at least a surface blocking) first, which isn't bad for arteries or bones, but could take a long time if you had a lung or a brain. If it is somewhat regular, you could try FE Molder (Workbench) which is a more automatic way to get the job done, but often fails for highly irregular biomedical parts. But there is a whole industry around surfacing faceted models; you could start with our sister company (now independent) ICEM Surf. This still requires effort, but since it is their focus, they should be pretty good at it. I actually haven't needed to surface facets for quite a while because ICEM CFD is so good at meshing directly from the facets. You may want to ask yourself why you are surfacing. If it is for simulation, you can skip it and save a lot of time. If you want a CAD model for some other reason, check if your primary CAD package has anything that can help. Then try ICEM Surf.

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July 23, 2009, 10:21		#3
snudurupati New Member sai Join Date: Jun 2009 Location: New Jersey Posts: 9 Rep Power: 16	Thank you for your reply. That was really helpful for my understanding. The geometry will be starting from simple structure to complex structures like valve mechanisms in the heart. Would the Hexa meshing be appropriate? I did not get a complete feel for the hexa mesh yet but I can see that it is very useful. But what are the limitation for Hexa mesh?? Is is the geometry? I tried the FE Modeler, but it will not accept .stl format. Rather I can use 3-rd party software like Rhino to create Facets and then import as IGES to Modeler Also right now i am concerned with only the simulation, but in the near future i will require the CAD model to convey other parameters like the non uniform wall thickness, hyperelasticity of the wall etc. I will also look into ICEM Surf!! Do you happen to know if I can use a trial version for this software?? Right now I am confused as to which software to use which will be helpful in the long run i.e, when I encounter Complicated geometry and Moving Boundary and two way FSI.