How to Model a Revolute Joint Correctly with Nastran


Updated by Altair Forum User
Hi,
I'm trying to model a revolute joint as part of a 1D element actuator mechanism in NASTRAN. I have created the simple model in MotionView and it works, however I need to understand how to model this correctly and that the kinematics work for a static analysis when I introduce the rest of the structure and stops into the system.
My problem is that my RBE2 is elongating - I need it to stay the same length so that the actuator deforms correctly. Can someone check my .bdf input and see if I've made any errors with the DOFs or missed something simple? It is really very simple - only 4 GRIDS!
For reference, I've attached the MotionView output of how the elements should displace.
Thanks in advanced,
Matt
SOL 101 CEND VECTOR(PLOT,SORT1,REAL)=ALL DISPLACEMENT = ALL ELFORCE = ALL GPFORCE = ALL SPCFORCES = ALL $ SUBCASE 1 LABEL= Lift SPC = 1 DEFORM = 2 ANALYSIS = STATIC BEGIN BULK PARAM,POST,-1 GRID 1 0.0 0.0 0.0 GRID 2 345.656 0.0 -15.423 GRID 3 287.795 0.0 -36.262 GRID 4 287.795 0.0 -36.262 RBE2 2 2 123456 4 RJOINT 3 4 3 12346 CROD 1 1 1 4 $ PROD 1 1314.159315707.96 MAT1 172000.0 0.3 $ $ SPC 1 1 12346 0.0 SPC 1 2 12346 0.0 DEFORM 2 1 109.71 $ ENDDATA