RBE3 - Slave node with Boundary Condition

IRA_EM_21281
IRA_EM_21281 Altair Community Member
edited October 2020 in Community Q&A

Hi Folks,

 

I am curious how the solver finds a solution when the dependent node (slave) has a boundary condition Uy=0 at the SPC shown in blue. See attached.

 

In the case of a rbe2 element, it is clear that the independent node (master) would have the BC Uy=0 and thus the dependent node set can be solved for.

 

Any comments?

 

 

<?xml version="1.0" encoding="UTF-8"?>RBE3_ReactionForce.PNG

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Answers

  • Adriano_Koga
    Adriano_Koga
    Altair Employee
    edited July 2020

    that's exactly why you cannot apply a BC in RBE3. You will be generating kinematic conditions conflict, thus an error.

     

    For constraining a RBE3 dependent, you could use as a workaround, create a CBUSH attached to the RBE3, with RIGID stiffness, and ground the CBUSH node.

  • IRA_EM_21281
    IRA_EM_21281 Altair Community Member
    edited July 2020

    That's what I thought but the model solved successfully and so I looked into it further. It seems Optistruct uses PARAM, AUTOMSET to switch the dependent to an independent 

    image.png.c24622b55bb268f9320510ea59a441f2.png

     

    Now I am wondering does the element still behave as an rbe3?

     

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