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Slice with curve plus match across slice not matching mesh

Valued Contributor
Valued Contributor

Using Femap 11.3.1

 

See solid body with the 2 smaller holes in figure 1.  I am tet meshing this solid.  I wish to create 2 layers of small elements around the hole and the rest of the mesh can be much coarser. In figure 2, you can see that I created concentric circles that represent the 2 layers.

 

I used the command: Slice > With Curve > Match Faces across slice.  I then select the main solid to be cut and I select the concentric curves to use as cutting tools.  The geometry that results is perfect: the main solid body now has a hole with two concentric pipes running through it.

 

Figure 3 shows 1 of the "pipe solids" highlighted in yellow as an example.

 

However, the meshing does not obey the 'match face across slice' as can be seen in figure 4.  I set a small mesh size on the pipe solids and a larger mesh on the main solid.  The meshes do not match at the interface. This seems like a bug in the slice command since I specifically asked to match across slice.

 

How can I accomplish my goal?  I have also tried slicing using "Geometry > Solid > Embed Face" and I get the same results (i.e. unmatched mesh).

 

Figure 1:

c1.JPG

Figure 2:

c2.JPG

Figure 3

c3.JPG

Figure 4

c4.JPG

3 REPLIES

Re: Slice with curve plus match across slice not matching mesh

Solution Partner Phenom Solution Partner Phenom
Solution Partner Phenom

Hello!,

You need to select simultaneosly the 3 solids in order to run OK the "Adjacement Surface Matching" feature of the "MESH > MESH CONTROL > SIZE ON SOLIDS" command.

automatic-mesh-sizing.pngautomatic-mesh-sizing-surface-matching.png

Best regards,
Blas.

Blas Molero Hidalgo, Ingeniero Industrial, Director
IBERISA • 48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog Femap-NX Nastran: http://iberisa.wordpress.com/

Re: Slice with curve plus match across slice not matching mesh

Valued Contributor
Valued Contributor

Blas - Thank you.  But how can I have different sizes on the different solids if I use your solution?  It will override individual sizing.

 

I want  small elements where I need them ->pipes and larger elements where I can -> main block.  Femap should enforce same size at interface and then transition to coarser elements automatically. 

 

Is this not possible in Femap?

Re: Slice with curve plus match across slice not matching mesh

Solution Partner Phenom Solution Partner Phenom
Solution Partner Phenom

Dear Salad,

The meshing approach is basic in FEMAP: go from global to local, first in solids, next in surfaces and finally in curves!!. I have recreated a simply problem, each solid has a different color.  

 

mesh-transition1.png

I have applied a global element size =5.0 to all solids using command MESH > MESH CONTROL > SIZE ON SOLIDS, using a Max angle tolerance = 15 (default is 25):

mesh-transition0.png

The result is the following:

mesh-transition2.png

And here you are the resulting TET mesh: a regular mesh, not mesh transition used.

mesh-transition3.png

But if you want to have refined mesh in the inner solids then DELETE TET MESH and use command MESH > MESH CONTROL > SIZE ON SURFACES and using METHOD=BY SOLID select all surfaces of the inner solids (pipes) using -for instance- and Element Size=2.5 mm

mesh-transition4.png

The result is the following, make sure that all curves have the same element size as well, use locally command MESH > MESH CONTROL > SIZE ALONG CURVE as required, OK?.

mesh-transition7.png

Next TET mesh the solids, make sure to activate MERGE NODES option:

mesh-transition5.png

The result is a refined mesh in the inner solids ....

mesh-transition6.png

But if you want to have a quality mesh & accurate stress results with minimum model size I suggest to forgot at all using TET meshing and play with HEX MESHING + MESH TRANSITION using command MESH > MESH EDTING > INTERACTIVE, then you will arrive to examples like in the following picture: next you can combine TET with HEX mis¡xing mesh elements using GLUE SURFACE-TO-SURFACE, is a great feature in NX NASTRAN solver:

MESH-TRANSITION-EXAMPLE.png

To learn more take a look to my blog in the following address:
https://iberisa.wordpress.com/2015/05/17/2-d-transition-mesh-in-femap/

Best regards,
Blas.

 

Blas Molero Hidalgo, Ingeniero Industrial, Director
IBERISA • 48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog Femap-NX Nastran: http://iberisa.wordpress.com/