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# Equivalent Mesh For Coincident Nodes

Valued Contributor

Hello,

I have two surfaces (shells) which I want to join by a bond: eg:- Two composite parts with resin in the middle (See Figure: Geometry).

I created partitions on the larger surface so that the meshes can line up. However, my meshes do not exactly match on the two surfaces where it is bonded. I have tried using Combined/ Boundary Curves and Surface to ensure that the surfaces dont have short edges but I cant get the mesh to match. (See Figure: Non Matching Mesh at Bond).

What other techniques can I use to get the both surfaces to have the same meshes.

Once the meshes match, I also want to create solid elements in between. Is there a command for creating someting like that.

Regards,

Saptarshi

3 REPLIES

# Re: Equivalent Mesh For Coincident Nodes

Valued Contributor

If they have "matching" faces and edges, you could play with the Mesh->Mesh Control->Size Along Curve and specify the number of elements so they are all equal.

Or you could define a glued region between the parts.

# Re: Equivalent Mesh For Coincident Nodes

Solution Partner Phenom

Hello!,

You can use command "Mesh > Mesh Control > Approach On Surface > Matched - Linked to Surface". This option simply instructs FEMAP to make the mesh on the selected surface match the one on the surface that you link it to. This approach is primarily used to insure compatible meshing in a single solid for hex meshing, and to insure compatible meshes between adjacent surfaces of multiple solids. You can use it for certain other situations, but care must be taken:

• Surfaces to be linked must either be on the same solid, or must be adjacent/coincident in space, or must at least be closely aligned.
• If surfaces are on the same solid, they can be anywhere in space. They do not have to be parallel or aligned in any particular fashion, but they can only be linked if the other curves on the solid directly connect the two sur­faces. In this mode, linking surfaces is intended to be used with hex-meshable solids only. That is, solids that are essentially extrudable. If you have more complicated geometry, you will still be able to link the surfaces, but meshing the linked surface will fail.
•  If surfaces are not on solids, or are on different solids, then they are meshed by matching the closest points on the surfaces. For this reason, to mesh properly, the surfaces must be positioned and aligned so that the points on the curves that are closest to each other result in the proper mapping between the surfaces. Surfaces that are rotated arbitrarily in space relative to each other will usually not meet this criteria. Again, this mode is primarily intended for matching adjacent surfaces between multiple solids.
• Surfaces to linked must also have the same mesh sizing, or they will not mesh properly. In order for a linked sur­face to be meshed, it must have the same mesh sizing as the master surface.
• You cannot define circular references. You can only slave surfaces in one direction, that is if A is linked to B, then B must be independently meshable, it can not be linked to A.

Then in order to run the above meshing approach and to create the solid between the TOP and BOTTOM surface the best command we have in FEMAP is "Geometry > Solid > Sweep Between", this is a great command, and this should be the first step in the workflow!!. This command allows you to create a solid between two selected surfaces. A single point on each surface is also selected and used as a reference. The selected points are used by the command to determine which curves on each surface should be “matched”. The Sweep Type (“path”) used to create the solid must be LINEAR, this is the key, OK?. Enjoy!!.

Best rgards,
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: Equivalent Mesh For Coincident Nodes

Valued Contributor

Thank you AllTrans and Blas for your help.

What worked out best for my situation was:

1) I projected the curves from one surface to the other surface using Meshing Toolbox -> Geometry Editing -> Project Curves

2) I matched the curves using Meshing Toolbox -> Mesh Sizing -> Match Curves

3) Then I used Geometry > Solid > Sweep Between

Regards,

Saptarshi