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Incorrect classification of spring forces and moments of Celas2 in Post

Gears Phenom Gears Phenom
Gears Phenom

Hello experts,


I did manage to define an element birth situation for having a deformation fixed in SOL601 AFTER a load application.

I did deform a shell structure with pressure and after reaching final deformation state I fixed its free rim by element birth of Celas2(to ground)-elements for 2 DOFs: Vertical displacement (u.z) and lateral rotation (rot.x).

Afterward I unloaded the structure and I've got a deformation state depending from fixed u.z and fixed rot.x.


As I tried to find out the reaction forces and moments for this I had to determine that there was no torsional moment in X with Nmm as its unit but only a spring-force in X with unit N. Furthermore I had to detect that my Celas-elements for fixing u.y also had spring forces only in X direction.


OK, getting force results for an axial-spring (Force / length) in "native" coordinate system direction 1 as a result of a fixed deformation is imaginable but getting force results for a torsion-spring (Moment / angle) as a result of a fixed rotation is weird. How shall I get information about the reaction moment now?


Is it a known bug? Who can explain it?

As the internal unit system of NX Nastran is mN, mm, kg, and so on what conversion factor do I have to use to translate a result value describing a moment (Nmm) but given in "N"? - Who can help?


Best wishes, Michael

NX10 , large strains + displacements


PS: As a differencial analysis I did use CBUSH(to ground) and here I've got the correct classification.

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