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Unrefine Mesh



I have a assembly model comprising of over 100,000 elements. I am not interested in most of the model except a small area with high stress concentration.


My questions are:


1) Is there a way to select the entire model and unrefine it.


I tried using the Mesh->Remesh->Unrefine Command but I get the following error: Free edges of selected elements do not form a single closed boundary.


2) If a go part by part, I have coincident nodes at the part boundaries which I also want to unrefine? 


How can I do this.


Any help regarding this would be appreciated.








Re: Unrefine Mesh

Dear Saptarshi,
With FEMAP you can use the GLOBAL-TO-LOCAL "Breakout Modeling" approach. Please visit by BLOG in the following address where I explain how to use it, including a video with an example explained step-by-step:


Best regards,

Blas Molero Hidalgo, Ingeniero Industrial, Director
Blog Femap-NX Nastran:

Re: Unrefine Mesh

Thank you Blas for your comment.


However, my application requires me to unrefine a very finely meshed model first. Once I do that, then I can proceed with what you have recommended.


The model does have any geometry associated with it. I can create surfaces from the mesh and then remesh the surfaces. However I was looking for a more simplified command where I select a whole buch of elements and Femap readjusts the nodes to remesh the elements.





Re: Unrefine Mesh

Such a process solution fit?

(view in My Videos)

Re: Unrefine Mesh

Hi Cfytrr,


Thank you for the video. I really appreciate it.


What you showed on the video about changing the mesh size is what I need to do; however the mesh I have is an orphan mesh. There is no geometry associated with it. 


Since I don't have the CAD I can create geometry from the mesh and associate it but I would have though that there would be another way.


So far what I have found to be the best approach is to use Mesh->Remesh->Update. The issue with the update mesh is that it is not a mapped mesh.


Once again thank you for your comments.






Re: Unrefine Mesh

Continuing from the previous discussion, this is what I am trying to do. I have a part with a very coarse mesh (See Image large Mesh Size).


The adjoining parts have much finer mesh (See Image Large Mesh and Small Mesh Interface). Instead of refining the larger mesh, I want to unrefine the small mesh and then use the coincident nodes option to merge the interface.


The problem is that the geometry is not associated with the mesh so I cannot remesh the surface using quads. I tried using the Mesh->Remesh option however the element flow is not ideal. 


At this point I am thinking to extract the geometry from thew mesh and then remesh the surface (I get good mesh trasition using this method). But I was hoping there would be a better way to do this.Image Large Mesh and Small Mesh InterfaceImage Large Mesh and Small Mesh InterfaceImage Large Mesh SizeImage Large Mesh Size