CYCSET

Bulk Data Entry Defines surface pairs for TIE-based cyclic symmetry boundary constraints.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
CYCSET CYSID
MSID1 SSID1 SRCHDIS1
MSID2 SSID2 SRCHDIS2
etc.

Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
CYCSET 1
1 2 2.567
3 4 2.567
6 7 1.932

Definitions

Field Contents SI Unit Example
CYSID Unique cyclic symmetry set identification number.

No default (Integer > 0)
MSIDi Identification number of main (SIDE 1) surface set (SURF) of the i- pair.

(Integer > 0)
SSIDi Identification number of secondary (SIDE 2) surface set (SURF) of the i-pair.

(Integer > 0; SIDi ≠ TIDi)
SRCHDISi Search distance criterion for creating cyclic symmetry condition following a rotation of the secondary surface to the main surface, about the symmetry axis, for the i-pair. When specified, only (internally rotated) secondary nodes that are within SRCHDIS distance from main surface have contact condition checked.

Default = Half of the main element size (Real > 0 or blank)

Comments

  1. The CYCSET card is valid only for cyclic symmetry analysis. For single stage symmetric models, having multiple CYCSET cards with unique CYSIDs, or one CYCSET containing all surface pairs as continuation lines derives an equivalent result.
  2. CYCSET cards cannot co-exist with CYJOIN cards. A cyclic symmetry model should contain either, but not both. CYCSET is an alternative to CYJOIN when the 3D mesh on the symmetric boundaries is not compatible between main (SIDE 1) and secondary (SIDE 2) surfaces.
  3. When CYCSET is used, the axis of symmetry must be user-specified via the CYAX entry, by setting PARAM, AXCYSYM, YES. Otherwise, OptiStruct returns an error message.
  4. MSIDi and SSIDi must reference surface sets (SURF). SHELL element faces and 2D TIE cyclic symmetry constraints are not currently supported.
  5. SRCHDIS is defined as in the TIE contact, following the rotation of the secondary surface towards the main surface, with respect to the symmetry axis (Figure 1). CYCSET internally generates MPC constraints, with secondary grids (SIDE 2) as dependent and main (SIDE 1) as the independent grids. Adjustment of secondary grids on the main surface is not supported (similar to the ADJUST entry in TIE contact).
    Figure 1. Definition of Main and Secondary Surfaces in Cyclic Symmetric Model


  6. As in CYJOIN, at the segment interfaces, all components of displacement at secondary grids are constrained to adjacent segments during the analysis, except those constrained by SPC or assigned dependent by MPC, RBE2 and RBE3.
  7. If a grid is repeated in multiple SSIDi sets, OptiStruct skips all corresponding MPCs and issues a warning.
  8. For the calculation of the SPCFORCE on the symmetric boundaries, only the grid of the secondary surface with the greatest MPC weight factor with respect to the corresponding main grid is considered.
  9. Supported analysis types include linear static (STATIC), normal mode analysis (MODES) and implicit nonlinear (NLSTAT & NL-DTRAN) analyses. Prestressed analyses are also supported with STATSUB(PRELOAD).