Submodel help. 1

[Simon012]

Hello,
I made a big Global model, and i want to focus on a small part of that Global mode by using Submodel technique.
I notice that all sets generated in the Global model are not propagated to the Submodel when these sets are created in the Assembly module, and i got a generation failed message in the Assembly module, and i see a red cross beside all these sets in the Assembly module. However, i do not get this message when all these sets are created in the Part module in the Global model.

So, my first question is: to use the submodel technique, all the sets should be created in the part module? please correct me if i am wrong.

My second question is, when i run the Submodel which covers a small region of the Global model, i get warning messages about "unknown set-1, unknown set-2, etc...", all these sets are defined with initial conditions in the Global model.

So what is wrong with the Submodel? Please Advice me.
Thank you in advance.

 

[portliner]

I use submodelling sometimes. Its better to prepare the GLOBAL model for its use as governer of the SUB model.
1. Create a cell by partition in the GLOBAL model. Use this cell as the SUB model later on.
2. Create *Nset on the interfaces between the cell and the rest of the GLOBAL model.
3. Print displacements for the nodes in this *Nset to the, I think, ODB-file. These to be used as driving nodes for the SUB model.

SUB-model.
1. Make a finer mesh of the cell above. You can make a copy of the GLOBAL model and remove irrelevant items
2. Apply BC on the interfaces of the SUB model. An option call "sub# something exist on the BC manager in the CAE
3. If you have pressures, temperatues etc, covering the sub model region, you must apply them on the sub model as well.
Make sure you combine coresponding driving BC and external loads if they vary in time.

 

[Simon012]

Thanks Portliner for your help.

Let me explain explain the Global model for you, the model is Three dimenions, i change the material properties of ten sets of the Global model in 10 steps, i.e., in each step i change the material properties of one set , i make these sets softer than before. Due to softening these sets, other regions in the model will be subjected to stress concentration.
I am interested in these regions which are subjected to more stress due softening the ten sets of the Global model. I used field variable card to change the material properties of these sets (*Field, variable=n) and i used (*initial conditions card) to define the initial conditions of theses sets.

"IN the submodel", I make copy of the Global model, then i go the part module and cut the regions that i do not need, and keep only the interested regions. So the submodel does not contain most of the these sets defined before in the Global model. i need to run the submodel again and see the effect of softening these sets.

I got this message (unknown set-1, unknown set-2...), because some of theses are no longer part of the submodel, but if i delete them how the can i soften them in the submodel?

My question is shall i delete these sets from the submodel?

I hope you could understand my model.
Thanks and please advice me, if you need any expalantion, i would be happy to explain again.

 

[Simon012]

Please read this post and the previous one, let me explain more. In the Global model, i am making Back-filling or rock material, so i change the properties of the intact rock with the properties of the back-filling. the back-filling is softer than the original intact rock. In my model i have pillars or columns, Due to back-filling, more load transfer to these pillars, i am interested in the pillars, because i design them.

So in the Global model, i divide the back-filling regions by 10 sets, and the model is solved in 10 steps, in every step i soften one of these sets. Again i am interested in the pillars, that is why i make submodel which has some pillars and some of the sets ( back-filling regions).

I need to run the Sub-model again with finer mesh and see what will happen when i soften these sets (making the back-filling).

As i mentioned in the previous post, i copied the Global model and keep only the pillars and parts of some sets.

Remember that these sets was defined by *initial conditions in the Global model so i can change their material, and since the submodel is a copy of the Global model, so i still have all these sets.

My question is shall i remove the definition of the initial conditions of these sets in the submodel or not? But if i remove them as i mentioned before i need to re-run the submodel again like the Global model and see what will happen when i soften some regions of the model.

 

[portliner]

Hello Simon012,
I have no experience of changing material properties. However, I believe You should change the *Initial conditions of the relevant parts in the sub-model as You did in the global-model. As I understand, your sub-model extends into regions where you change the material properties(softening), if so you should definitely change the material properties in the sub-model for sure. I am celebrating midsommer holday today, be back on sunday. I hope you got the model right. I am interested in the results.