Point symmetry (POINT_SYM)

To be able to couple displacements symmetric to a point, the position of the point must be exactly specified. It is also necessary to specify tolerances in order to identify nodes that lie symmetric to one another relative to the point. The following three parameters are necessary for the definition of the link condition:

      
        CLIENT = POINT_SYM
        CS = name_of_coord_system
        OL = <tol_1>, <tol_2>, <tol_3>
      
    

The origin of the coordinate system referenced by CS defines the symmetry point. The symmetry of the nodes (assigned by ND_GROUP in the DVCON_SHAPE command) is checked against the symmetry point. Symmetric nodes are assembled into a symmetry group (normally two symmetric nodes per symmetry group). Then the master node of the symmetry group is determined and the displacements of the client nodes are calculated in such a way that they move symmetric to the point of the master node (see the following figure).

The tolerances are required in order to identify symmetric nodes. Point symmetric nodes share inversely equal coordinates (and added tolerances). The three tolerance values tol_* are assigned to the three coordinate directions of the coordinate system referenced by CS.

Note:

• The coordinate system referenced by CS must be a Cartesian coordinate system.
• Only the MASTER=MAX or MASTER=MIN criteria are allowed for determination of the master node.