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Problems in BCS

Hi,

I simulated a ship collision analysis.

Initially BCs applied to some nodes in all 6DOF till few time, later some of the BCs removed and only one BC applied in second Engine file.

Initially the BCs were performed fine till 0.1sec (as attached in image for first Engine file). But in the second Engine file the applied BC (/BCS/TRA/Z/1) is not activated and the model starts moving along Z direction due to gravity.

What is the most probable reason for this issue.

Kindly resolve it.

<?xml version="1.0" encoding="UTF-8"?>

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Radioss

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Altair Forum User

Hi Pritam,

BCS looks fine in restart file, not sure if the skew is causing the error. Can you constraint in global direction instead and check if that helps?

Altair Forum User

Dear Prakash,

It seems the skew is fine as the INIV/TRA/Y/1 card works fine with the same skew.

as you suggested, the skew is in global direction only, no other skew applied.

Thanking You.

Altair Forum User

@Pritam K

Is it possible to share the model file?

Please use the file transfer link in my signature to share the model file

Altair Forum User

@Pritam K

Is it possible to share the model file?

Please use the file transfer link in my signature to share the model file

I shared the model file

Altair Forum User

Hi @Prakash Pagadala

Is the problem solved?

Altair Forum User

Hi Pritam,

I ran a similar case on a simple model as your model is taking time to complete.

BCS/TRA works fine on a simple plate model.

Right now, I am checking your model and I will get back to you with details.

Altair Forum User

Thanking You @Prakash Pagadala

Waiting for your reply.

Altair Forum User

Hi @Pritam K

Can you try BCSR to release the Dofs from the 1st engine and retain what is necessary and check if that helps?

Altair Forum User

@Pritam K

Here are the findings:

Make sure the ID 50903429 is the id of Master node (RBID) of RBODY and not the element ID

In the second Engine file I could see /RBODY/OFF on 50903429, so the BC on that node will not be applied. This is the main reason why it is not working.

Altair Forum User

Make sure the ID 50903429 is the id of Master node (RBID) of RBODY and not the element ID

The ID 50903429 is the master node of RBody, and not the element ID.

In the second Engine file I could see /RBODY/OFF on 50903429, so the BC on that node will not be applied.

Here the node 50903429 is only OFF, but the BC should apply for rest of the nodes (i.e. 50000000 to 50903428)

I modified the /BCS/TRA/Z/1 from :

/BCS/TRA/Z/1

50000000 to 50903429

/BCS/TRA/Z/1

50000000 to 50903428

but there is some unexpected behavior occurs.