How to Model a Revolute Joint Correctly with Nastran

User: "Altair Forum User"
Altair Employee
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

 

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