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How do I define support conditions for axisymmetric elements?

All nodes of axisymmetric elements lying on the axis of symmetry must be restrained to prevent any radial displacement across the symmetry axis. To displace in such a way (even by a small amount) would violate conservation of energy laws. If support conditions are not imposed, such violation can go undetected or can produce pivot and/or Jacobian warnings in the output file – but either way, the results could be significantly inaccurate. Axial support is additionally required to prevent axial rigid body motion

Nodes not lying on the symmetry axis are normally required to displace without restraints from supports. The radial support in this case comes from the hoop stiffness of the element formulation. The only support required is axial in this case 

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