how to get translation in local element set and not in global assembly.

[Crowner]

Hi everybody,
I need for a python skript the displacement of each node of an element set caused by the deformation of this one. All those element sets are in one global assembly and i can get the displacement (not the rotation though) for each node in the global coordinate system, but this doesnt reflect at all the displacement caused by the deformation of the piece.

How can i somehow remove the rotation and translation to get only the displacement caused by the deformation? Im having trouble to figure out a working strategy, my first thought was to identify the smallest overall displacement and substract this one from all the others, but this would only work if there would be no rotation and im not really happy with it.
So if anybody would have a good idea, i'd be really thankful.
Thank you!

 

[Mustaine3]

In postprocessing with /CAE create a CSYS that moves with a node or 3 nodes.
Then transform your results into that CSYS and activate the rigid body transformation options.

 

[Crowner]

Hi Mustaine3,
Thanks for you help, will this still work when my body is non rigid? I can define a coordinate system of the undeformed part using 3 nodes but this coordinate system will change as those nodes are non rigid.