# Rotational Degree of Freedom in ANSYS

Hello sci.engr.mech group,
I'm an electrical engineering student working in MEMS modeling
analysis using the ANSYS Multiphysics/LS-DYNA software for
verification of our simulations. Currently I'm modeling a plate/shell
element based on J.S. Przemieniecki's "Theory of Martrix Structural
Analysis". I've done a simple analysis of a single plate/shell
element with 4 nodes. I've constrained 3 of the 4 nodes and applied a
1uN force in the z-direction on the unconstrained node. I'm happy
with the results compared to the matrix model we've created in the UZ
displacement, but I'm trying to determine what units are used when the
output from ANSYS displays ROTX, ROTY, and ROTZ. Are these in units
of radians? If so, is the radian angle taken from the center of the
element? My matrix results are not converted to radians and I'm
trying to find some way to convert my results to see if they match or
are close to ANSYS. Hopefully I'm not too confusing in my question.
Thanks very much,
Michael Bails
University of Pittsburgh
Department of Electrical Engineering
Displacements (translations and rotations) occur at the nodes. Shell elements have 6 degrees of freedom (displacements) for each node. The rotations should be in radians.
If you want more specific info, try the Ansys web page.
"drill direction" of rotation is usually constrained if that particular node is not connected to any other structure? I remember using NASTRAN and having to use AUTOSPC to constrain singular d.o.f's Not sure what is done in ANSYS Robert
The common shell elements have a zero stiffness for the out of plane rotation DOF (drilling DOF). This can be taken care of by constraints or with the Param K6ROT in Nastran. Nastran has a new revised elements that have the 6th dof, but they don't work as well for most problems.

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