orphan mesh 3

An orphan mesh is a mesh that has no geometry associated with it. You can create an orphan mesh in a couple of ways:
1. You import from an existing ABAQUS inp or odb. When you import you only get the nodes/elements (no geometry, hence orphan)
2. You have meshed some geometry in CAE then you choose "Mesh-Create Mesh Part". This as the name suggests, creates a new part which is a copy of the nodes/elements (but not geometry).

So to your question: you only need to instance one or the other in the assembly. If you decide to, you can use "Instance-Replace" to swap the original "native" geometry part with the new "orphan" part. Loads/BC's etc will be applied to whatever you have in the assembly.

Finally, it is quite valid to mix orphan parts and native parts in the same assembly - CAE makes no restrictions on this. You can then have contact (etc) between such instances...

Hope this helps!

thanks a lot for your help.
so , I can isntance either one or the other. basically i created an orphan mesh using the mesh -create orphan mesh, as i need such an orphan mesh to place cohesive elements on its surface. Then, if i understand correctly, i can use this new part in the assembly module neglecting the original part.
thanks again

You're exactly right. The use-case you are describing is a perfect example of using orphan mesh parts. Let us know how you go with the model!