DSYM
DSYM, Lab, Normal, KCN
Specifies symmetry or antisymmetry degree-of-freedom
constraints on nodes.
LabSymmetry label:
SYMM
—
Generate symmetry constraints as described below (default).
ASYM
—
Generate antisymmetry constraints as described below.
NormalSurface orientation label to determine the constraint set (surface is assumed to be perpendicular to this coordinate direction in coordinate system
KCN):X
—
Surface is normal to coordinate X direction (default). Interpreted as R direction for non-Cartesian coordinate systems.
Y
—
Surface is normal to coordinate Y direction. θ direction for non-Cartesian coordinate systems.
Z
—
Surface is normal to coordinate Z direction. Φ direction for spherical or toroidal coordinate systems.
KCNReference number of global or local coordinate system used to define surface orientation.
Notes
Specifies symmetry or antisymmetry degree-of-freedom constraints on the selected nodes. The
nodes are first automatically rotated (any previously defined rotations on these nodes are
redefined) into coordinate system KCN, then zero-valued constraints
are generated, as described below, on the selected degree-of-freedom set (limited to
displacement, velocity, and magnetic degrees of freedom) (DOFSEL). Constraints
are defined in the (rotated) nodal coordinate system, as usual. See the D and
NROTAT commands for additional details about constraints and nodal
rotations.
This command is also valid in PREP7.
Symmetry and Antisymmetry Constraints:
Symmetry or antisymmetry constraint generations are based upon the valid
degrees of freedom in the model, that is, the degrees of freedom
associated with the elements attached to the nodes. The labels for degrees
of freedom used in the generation depend on the Normal label.
For displacement degrees of freedom, the constraints generated are:
| SYMM | ASYM | |||
|---|---|---|---|---|
Normal | 2D | 3D | 2D | 3D |
| X | UX, ROTZ | UX, ROTZ, ROTY | UY | UY, UZ, ROTX |
| Y | UY, ROTZ | UY, ROTZ, ROTX | UX | UX, UZ, ROTY |
| Z | -- | UZ, ROTX, ROTY | -- | UX, UY, ROTZ |
For velocity degrees of freedom, the constraints generated are:
| SYMM | ASYM | |||
|---|---|---|---|---|
Normal | 2D | 3D | 2D | 3D |
| X | VX | VX | VY | VY, VZ |
| Y | VY | VY | VX | VX, VZ |
| Z | -- | VZ | -- | VX, VY |
For the 2D vector magnetic degree of freedom, AZ, symmetry is naturally satisfied and the SYMM label generates no constraints. The ASYM label generates flux parallel conditions (flux flows parallel to the surface).
| SYMM | ASYM | |
|---|---|---|
Normal | 2D | 2D |
| X | -- | AZ |
| Y | -- | AZ |