Meshing an assembly of differents materials 1

[mechzgz]

So i have this question. I've build a design with abaqus(5 parts) that i imported to Abaqus. I have 3 differents materials.
What i've done is, give every part its own material, then build the assembly, and merge the 5 parts. With merge it generated one part of the assembly, are still the differents materials asigned?
Also, when i merge with dependent instance one of the part disappear,i read that may it was better than instead of mergin it, use a costraint. Can anyone tell me how should i use the costraint? If i use the costraint for this 2 parts, should i use also merge for the rest of the assembly?

I know..to much question, but it's difficult to find answers about abaqus

 

[FEA way]

It's definitely better to use tie constraint instead of merging parts. When you define this constraint just select master and slave surfaces (surfaces belonging to different parts). This is very similar to defining contact but you don't specify property sińce behavior is always the same (no relative motion between surfaces). But if you still want to merge parts then make sure three are proper partitions and each cell (volume) has its material applied. You can use display options to color parts depending on the section/material.

 

[mechzgz]

Thank you friend. The thing is, I have a mold, where I have put the screw and the hole of the mold is equal to the screw. Screw fillets should go with constraint to the hole fillets, but those in the hole are not visible when the screw is inside. How i put the costraints?
And then to make the mesh, if I want there to be only one mesh for the entire object and also keep the materials, should Merge do after tie costraint and partition to give the material?

 

[FEA way]

You can use Display Group options to hide screw when selecting surfaces of the hole. Then invert the display so that only screw will be visible and you will be able to select its faces.

These two approaches are interchangeable fo the same group of parts. So either you merge them to keep uniform mesh (in such case partitions are needed to maintain different material properties) or you use separate meshes and materials and join the parts via tie constraint. For screws and holes I would recommend the second method (tie constraints).

 

[mechzgz]

Alright, i Will try it as soon as possible.
For the other parts, a crown on top oferta the screw, should i also use costraints? Or merging them?

Thank you

 

[FEA way]

This one could be merged but still I think it’s better to use tie constraint. One reason is that you can easily replace it with contact.

 

[mechzgz]

What do you mean replace with Contact? I had give every part their properties, and put the tie costraint between screw and model, should i put something between the crown and the screw? Another costraint?

Thank you

 

[FEA way]

At some point you may want to make the analysis more realistic and apply contact (possible relative motion of the surfaces) instead of tie constraint (no motion). Then it’s very easy to convert all ties using for example Find Contact Pairs tool.

But even if you don’t want any contact, still I would recommend tie constraint. It allows independent meshes (usually resulting in better mesh quality and less issues), works even with small separation between surfaces and so on.