Removal of rigid body motion for extraction of displacements

prasad.guduguntla.external over 3 years ago

Hello,

I got a structure with different substructures assembled to it.

All the structures are loaded and i am interested in displacements of substructures only (that means the displacements causing due to primary structure are need to be excluded).

Any suggestions would be helpful.

Thanks

0 Zach Fata over 3 years ago

In version 2021.3 of Nastran a new case control command, RELDISP was added to obtain relative displacement results from Nastran.
Cancel
Vote Up 0 Vote Down

Sign in to reply

Verify Answer

Cancel
0 prasad.guduguntla.external over 2 years ago

Hi

Thanks for the suggestion, the results from the Nastran analysis to analytical approach is almost matching with a deviation of 10%.

Could you please provide me the theory behind the case control command.

Thanks

Prasad.
Cancel
Vote Up 0 Vote Down

Sign in to reply

Verify Answer

Cancel
0 prasad.guduguntla.external over 2 years ago

Hallo

Is it necessary both the reference node and node of interest to be in same coordinate system?

Thanks
Cancel
Vote Up 0 Vote Down

Sign in to reply

Verify Answer

Cancel
0 Zach Fata over 2 years ago

I believe it just does a simple subtraction of the components. The results will output based on the global coordinate system of each grid but it is okay if the reference grid and node of interest are in different systems (the logic handles this).

I think there are some issues with the implementation for rotational rigid body motion. There is an existing enhancement request NAS-42893. This may be causing the discrepancy
Cancel
Vote Up 0 Vote Down

Sign in to reply

Verify Answer

Cancel