Learning Forum

[pengchengyin]

Does any body can help me? As the title, is there a way to do sub modeling in Ansys workbench ls-dyna? I cannot do the same way as usual.

[Sandeep Medikonda]

It is possible but using command snippets. Cut the CAD geometry and create a conformal mesh. Then, try the following procedure:

[pengchengyin]

Hi San,

Thank you for answering my question. I really appreciate it!! it helps a lot.

But I still have a question, may be sounds a little silly. How can I add the ls-dyna name selection manager? I cant find it at GUI of workbench LS-dyna.

Please reply me at your earliest convenient.

 

[pengchengyin]

also, when dong sub-modeling in workbench ls-dyna by using explicit dynamic, the  time-step is based on the smallest element size which means if I change the mesh size in sub model, the time-step will change. So I think it will be some problems at cut boundary. is that right? is there something else I need to do like force the time step? 

Thank you!!

[Sandeep Medikonda]

You should be able to insert it from the LS-DYNA toolbar:

That is a very good observation. Yes, you will hit a limitation with using explicit there. So, select a smaller region compared to what you would use in implicit and don't go crazy with the mesh  

[pengchengyin]

Hi San,

I am still confusing. Based on your said, I  need to select a small region to do the sub-modeling? And the software can match the time step automatically if I change the mesh size at sub-model? Because usually, we need to set time-step and load step by step in implicit analysis which is not fit for explicit analysis. So I think the workbench software will match the time-step when I change the mesh size in sub-model. Is that right?

And should I set the section part before input the keyword snippet?  Does the setting like the below image if I need to set section before inputting keyword snippet? And I found that when I set the section, the LS-DYNA ID is not the same as I set in LS-DYNA named selection manager( it shows in the detail window).Also could you please take a look at the keyword snippet I input, is that right or not?

 

Best regards,

Pengcheng

 

[pengchengyin]

also, when I solve this sample I made, there will be some errors as below image. it shows there are some problems in the keyword snippet. Could you please tell me how could I solve these?

 

[pengchengyin]

Hi San,

I tried to solve these problems but still cannot find the reason why the interface definitions cannot be defined,  even I also delete the control_output command. I just follow your step which you upload. I attach what I did as attachment. Could you please take a look at and tell me the reason?

 

Thank you,

Pengcheng

[pengchengyin]