*MPC Plane

I'm trying to keep a surface of a model in a plane.  I thought I had this fixed, but now it doesn't work.
The *MPC Plane instructions are pretty simple.  
I define Top_Nodes as a named group and put this in the CCX Model window.

*MPC
Plane,Top_Nodes

Also, I tried with individual node numbers.  Same results.

and I get this in the input file
*MPC
Plane,Top_Nodes
*STEP
*STATIC
*CLOAD
134,2,-100
*NODE FILE,GLOBAL=YES
U,RF
*EL FILE
S
*END STEP

I get these warnings in the output file and no results. I've checked and there are no duplicates between SPC's and the MPC Plane dof's
 *WARNING in nonlinmpc: coefficient of
          dependent node in PLANE MPC is zero
 *WARNING in nonlinmpc: coefficient of
          dependent node in PLANE MPC is zero
 *WARNING in nonlinmpc: coefficient of
          dependent node in PLANE MPC is zero
 *WARNING in nonlinmpc: coefficient of
          dependent node in PLANE MPC is zero
 *WARNING in nonlinmpc: coefficient of
          dependent node in PLANE MPC is zero
 *WARNING in nonlinmpc: coefficient of
          dependent node in PLANE MPC is zero
 *WARNING in nonlinmpc: coefficient of
          dependent node in PLANE MPC is zero
 *WARNING in nonlinmpc: coefficient of
          dependent node in PLANE MPC is zero
 *WARNING in nonlinmpc: coefficient of
          dependent node in PLANE MPC is zero
 *WARNING in nonlinmpc: coefficient of
          dependent node in PLANE MPC is zero
 *WARNING in nonlinmpc: coefficient of
          dependent node in PLANE MPC is zero
 *WARNING in nonlinmpc: coefficient of
          dependent node in PLANE MPC is zero
 Decascading the MPC's

 Determining the structure of the matrix:
 number of equations
 1395
 number of nonzero lower triangular matrix elements
 79958

 Using up to 1 cpu(s) for the stress calculation.

 Using up to 1 cpu(s) for the symmetric stiffness/mass contributions.

 Factoring the system of equations using the symmetric spooles solver
 Using 1 cpu for spooles.

Comments

  • One problem is that the first 3 nodes in the node set that Mecway generates for Top_Nodes lie on a line, which isn't allowed by *MPC.

    Another problem which I can't explain, is that it works when your scale up the size of the mesh by a factor of 10. Maybe it's a CCX bug.

    Here's a working model but it's 10x longer and has one node moved out of the line.

  • With *Rigid Body card you can find a solution.
    All surface nodes partecipates to rigid body

    There is a difference of stresses and deformations respect *MPC plane



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