Learning Forum

[valerym.m5]

Dear colleagues,

Below is what I read:

https://feassistant.com/forums/ls-dyna/how-to-give-displacement-to-constrained-nodal-rigid-body-body/

I'm not sure if this is possible, but

first you need to make sure that your reference node is the first node in the node set referenced by the constrained nodal rigid body (CNRB).

The first node is the source point and represents the center of the CNRB.

Then you can try to apply *Boundary_Prescribed_Motion_Node to that reference node.

If Dyna will not accept this, then you will need a different approach.

You can create a simple element (1D, 2D, 3D etc.) which uses that reference node.

Then make this part *Mat_rigid.

Then you will use *Constrained_extra_nodes_set and refer to the rigid part as the PID and the other nodes will need to be in a node set and be referred to in the NSID.

You will then be able to apply motion to the rigid part using *Boundary_prescribed_motion_rigid.

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At the same time, in the given model:

https://www.dynaexamples.com/.../Salzbur.../example_linear_3

• 3.4_Connectors_CNRB_Interpolation.key.zip

Two parameters are used:

NSID - if I understand correctly, this is a set of rigid body points + a "reference" point, all of which are fully described by Connectors CNRB.

At the same time, there is a parameter PID:=Part ID of the nodal rigid body.

It is set to 100.

If I understand correctly, the number of the "new" part defined by the operator:

Constrained Nodal Rigid Body (CNRB)

But there is no such part in the list of "parts."

Am I correct in understanding that this part number is an arbitrary number that the user must specify?!

And one more thing:
AFTER solving this problem, a new body, "10000000 Beam," appears in the list of "parts."
Before solving this problem, the "10000000 Beam" body wasn't listed as "parts."

Can anyone comment on my questions?

[Ram Gopisetti]

Hi, 

Please follow the steps below to see the CNRB in the part list , perhaps there is is an offset to the parts called in via INCLUDE_offset_user or INCLUE_AUTO_OFFSET

Cheers, Ram