CYCLIC
CYCLIC, NSECTOR,
ANGLE, KCN ,
Name, USRCOMP,
UsrNMap
Specifies a cyclic symmetry analysis.
NSECTORThe number of sectors in the full 360 degrees, or one of the following options:
STATUS
—
Indicates the current cyclic status.
OFF
—
Resets model to normal (non-cyclic) status and removes the duplicate sector if it exists. This option also deletes automatically detected edge components (generated when
USRCOMP= 0).UNDOUBLE
—
Removes the duplicate sector if it exists. The duplicate sector is created during the solution (SOLVE) stage of a modal cyclic symmetry analysis.
Note: The duplicate sector is necessary for displaying cyclic symmetry analysis results during postprocessing (/POST1).
If you specify a value of STATUS, OFF or UNDOUBLE, the command ignores all remaining arguments.
ANGLEThe sector angle in degrees.
KCNAn arbitrary reference number assigned to the cyclic coordinate system. The default value of 0 specifies automatic detection.
NameThe root name of sector low- and high-edge components (line, area, or node components). The default root name (when
USRCOMP= 0) is "CYCLIC". A root name that you specify can contain up to 11 characters.The naming convention for each low- and high-edge component pair is either of the following:
Name_mxxl,Name_mxxh (potentially matched node patterns)Name_uxxl,Name_uxxh (potentially unmatched node patterns)The
Namevalue is the default ("CYCLIC ") or specified root name andxxis the component pair ID number (sequential, starting at 01).USRCOMPThe number of pairs of user-defined low- and high-edge components on the cyclic sector (if any). The default value of 0 specifies automatic detection of sector edges; however, the automatic setting is not valid in all cases. (For more information, see the Notes section below.) If the value is greater than 0, no verification of user-defined components occurs.
UsrNMapThe name of a user-defined array specifying the matching node pairs between the sector low and high edges. Valid only when
USRCOMP= 0. Skips the automatic detection of sector edges. Node pairs may be input in any order, but the low edge node must be the first entry in each pair.*DIM,MYMAP,ARRAY,2,14 ! specifying 14 low-high edge node pairs *set,mymap(1, 1), 107, 108 ! low node 107 <> high node 108 *set,mymap(1, 2), 147, 211 ! low node 147 <> high node 211 *set,mymap(1, 3), 110, 109 ! low node 110 <> high node 109 ! etc for node pairs 4 through 14 cyclic,12,,1,,,MYMAP ! use array MYMAP to generate cyclic CEs
Command Default
The default CYCLIC command (issuing the command
with no arguments) detects the number of sectors (NSECTOR),
the sector angle (ANGLE), and the coordinate
system (KCN) based upon the existing solid
or finite-element model. The command also detects sector low- and
high-edge components in most cases and assigns the default root name "
CYCLIC" to the components.
Notes
You can input your own value for NSECTOR,
ANGLE or KCN; if you do so,
the command verifies argument values before executing.
When USRCOMP = 0 and UsrNMap = blank
(default), the CYCLIC command automatically detects low- and high-edge components for
models that consist of any combination of line, area, or volume elements. If a solid model
exists, however, the command uses only the lines, areas, and/or volumes to determine the low-
and high-edge components; the elements, if any, are ignored.
Nodes will be automatically rotated unless CYCOPT,USRROT,YES has been specified.
If you issue a CYCOPT,TOLER command to set a tolerance for edge-component pairing before issuing the CYCLIC command, the CYCLIC command uses the specified tolerance when performing automatic edge-component detection.
For 2D models, autodetection does not consider the CSYS,5 or CSYS,6 coordinate system specification. Autodetection for 180 degree (two-sector) models is not possible unless a central hole exists.
The CYCLIC command sets values and keys so that, if possible, the area-mesh (AMESH) or volume-mesh (VMESH) command meshes the sector with matching node and element face patterns on the low and high edges. (The command has no effect on any other element-creation command.)
Issue the CYCLIC command prior to the meshing command to, if possible, produce a mesh with identical node and element patterns on the low and high sector edges. Only the AMESH or VMESH commands can perform automated matching. (Other meshing operation commands such as VSWEEP cannot.) If you employ a meshing operation other than AMESH or VMESH, you should ensure that node and element face patterns match, if desired. The CYCLIC command output indicates whether each edge-component pair has or can produce a matching node pair.
A cyclic solution (via the SOLVE command) allows dissimilar mesh patterns on the extreme boundaries of a cyclically symmetric model. The allowance for dissimilar patterns is useful when you have only finite-element meshes for your model but not the geometry data necessary to remesh it to obtain identical node patterns. In such cases, it is possible to obtain solution results, although perhaps at the expense of accuracy. A warning message appears because results may be degraded near the sector edges.
The constraint equations (CEs) that tie together the low and high edges of your model are generated at the solution stage of the analysis from the low- and high-edge components (and nowhere else). You should verify that automatically detected components are in the correct locations and that you can account for all components; to do so, you can list (CMLIST) or plot (CMPLOT) the components.
If you issue the CYCLIC command after meshing and have defined element types with rotational degrees of freedom (DOFs), Mechanical APDL generates cyclic CEs for rotational DOFs that may not exist on the sector boundaries. Issue CYCOPT,DOF to prevent unused rotational terms from being generated.
Modal cyclic symmetry analysis is supported by the following eigensolvers:
To learn more about analyzing a cyclically symmetric structure, see the Cyclic Symmetry Analysis Guide.
When using the CYCLIC command to automatically detect the sector, if an area is defined with the AL command, the lines need to be oriented to form the closed curve.