How to bond two surfaces of two solids together?

[alin09]

Does PATRAN/NASTRAN have the capability to bond two surfaces of two solids together?

I tried to model an assembly consisting of two parts. The two parts share one surface. How can I glue these two together in order to obtain same nodes and mesh at the bonded surface?

 

[GregLocock]

You need to make sure that the surfaces in contact have exactly the same mesh, and the nodes are coincident. then merge the coincidient nodes.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[Onda]

I often use cweld elements to join two different components made of shell elements.
Using cweld you don't need to have coincident grid points

 

[GregLocock]

Doesn't that stiffen the structure?

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[Onda]

Is depending on what you are looking for.
In case you can use the Cfast, that allow for a defined stiffness in the connection.
In any case. I've never run a comparison between different method:
coincident grid point
cweld
cfast

will be nice if somebody have data on this.

 

[alin09]

Onda, Greg, thanks for the reply.

It sounds that the following methods can be used to bond two surfaces:
1.merge coincident nodes
2. CWELD connection
3. CFAST connection
4. RBE3 (someone suggest me this method)

All these ways need manual creation of grid points at the surfaces. I was wondering if I can "glue" two surfaces of two solids to one surface. When I mesh two solids, they have the same mesh at the bonded surface.

 

[Onda]

Cweld and Cfsast are usable only for shell element not for solid one.

You can glue two solid if you use MD nastran, not 'normal' nastran.
With MD nastran you can define two surface to be glued.
I can't say much more because I didn't use it.

 

[alin09]

Thank you, Onda.
I don't have MD Nastran. I'll check about that.

 

[BlasMolero]

NX NASTRAN support GLUE contact surface-to-surface, that means you can mesh two parts with different mesh size and the solver will bond both meshes (internally will use multipoint-contraints MPC). If msc.nastran don't support Glue contact, you can use RBE2 elements, or rigid beams, or contraint equations, you have plenty of methods to joint dissimilar meshes.

The clasical method I prefer is simply merging coincident nodes: if coincident solid faces has different area, then simply imprint one face in another and make sure you have exactly the same mesh in both faces, mesh your assembly with 3D solid elements and merge coincident nodes, simply!.

Best regards,
Blas.

 

[alin09]

Blas,

Thanks for the reply.

It is not easy to create many RBE3 manually. To make same mesh at both surface of solids might not be applicable to two solids.

I just found out that there is a contact option in PATRAN Load/BC. But the input file can only be solved by MD NASTRAN, not regular NASTRAN.