Automatic Brick Meshing: How to Achieve Mappable Surfaces

Question

Automatic Brick Meshing: How to Achieve Mappable Surfaces

RealSaladsamurai (Mechanical)

(OP)

21 Mar 16 17:42

I have the structure in the image (FEM attached).

I am trying to use the Mesh > Geometry > Hex Mesh on Solids...

I want to know the correct way to set up for this. This is what I have tried and it fails. I know I can use other mesh methods, but I want to use this method. This is a much simpler version of the CAD I am trying to mesh. I am building up in small steps.

1) Slice match across the red face to separate the main solid from the 3 extrusions

2) Curves from Surface > Project onto the bottom surface so that it face imprints to match the curves generated by the slice match in step 1.

I get the message Solid 4 can not be hex meshed. Either Meshes on lateral surfaces are not fully mapped or base and top surface meshes do not match.

Solid 4 is the large block.

Thanks for your help.

________________________
FEMAP v11.1.0
MSC Nastran v2013

http://files.engineering.com/getfile.aspx?folder=030ce2d3-807c-4993-bfc4-39

RealSaladsamurai (Mechanical) · Answer 1 · 2016-03-22 00:46:20

I was able to do this using embed face, but I cannot figure out how to put different mesh sizes on the different solids and still have it map. I should be able to put a fine mesh size on the 3 small solids and a coarse mesh on the larger solid and have it match up only where necessary (i.e. at the interfaces).

Any ideas?

________________________
FEMAP v11.1.0
MSC Nastran v2013

BlasMolero (Mechanical) · Answer 2 · 2016-03-22 21:17:26

Hello!,
The error message is clear: you need to have exactly the same geometry in top & bottom surfaces, "base and top surface meshes do not match". You need to do an imprinting on the bottom surface of solid4 projecting the curves in the top surface to have exactly the same shape in both Top & Bottom faces.

I am revising your FEMAP model, I see the imprinting is done, good, but this is not all.
If I CLEANUP the geometry and run the Mesh Sizing in Solids command for HEX meshing here you are the result: FEMAP do not find any matching surfaces, all colors are the same.

Well, in FEMAP you have many resources & tricks to HEX mesh this geometry, take a look to my BLOG to learn more, search for HEX MESHING, for instance:
https://iberisa.wordpress.com/2011/10/16/mallado-c...

For example, imprint the top surface with curves using command GEOMETRY > MIDSURFACE > TRIM WITH CURVE ...

The result is surface matching performed correctly

CODE -->

Mesh Size on Solid
4 Solid(s) Selected...
Computing Mesh Sizes...
Mesh Approach: Linking Surfaces 22 and 71.
Mesh Approach: Linking Surfaces 23 and 77.
Mesh Approach: Linking Surfaces 24 and 85.
Solid 4 can not be hex meshed. Unable to identify the surfaces for the base and top of the mesh.

Don't worry for the red color message, FEMAP complaints but the previous uniform splitting assure we have the same mesh density in top & bottom faces.
In fact, if we prescribe solid attributes to the geometry and HEX mesh the solids we will see ....

... total success!!.

You can also perform a 2-D QUAD4 meshing, extrude mesh to create 3-D solids HEX elements, and finally associate the mesh to geometry, this is another valid workflow as well.

Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

IBERISA
48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog de FEMAP & NX Nastran: http://iberisa.wordpress.com/

Come Join Us!

Posting Guidelines

Related Projects

Automatic Brick Meshing: How to Achieve Mappable Surfaces