CYJOIN

Bulk Data Entry Defines points on one of the boundaries that connect to adjacent segments in cyclic symmetry analysis.

Fomat 1

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
CYJOIN	`SIDE`		`GID1`	`GID2`	`GID3`	`GID4`	`GID5`	`GID6`
	`GID7`	`GID8`	`GID9`	etc.

Format 2

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
CYJOIN	`SIDE`		`GID1`	`GID2`	`THRU`	`GID6`

Example 1

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
CYJOIN	1		3	103	105	54	1130	1450
	7

Example 2

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
CYJOIN	2		2	23	`THRU`	27	122

Defintions

Field	Contents	SI Unit Example
`SIDE`	Side identification number. 3 1 Corresponds to the first side of the segment. 2 Corresponds to the second side of the segment. No default (Integer)
`GIDi`	Grid identification number. No default (Integer > 0)
`THRU`	Keyword used for ID ranges to indicate that all IDs between the preceding ID and the following ID are to be included in the set. This is applicable only for Format 2.

Field

Contents

SI Unit Example

SIDE

Side identification number. 3

1: Corresponds to the first side of the segment.
2: Corresponds to the second side of the segment.

No default (Integer)

GIDi

Grid identification number.

No default (Integer > 0)

THRU

Keyword used for ID ranges to indicate that all IDs between the preceding ID and the following ID are to be included in the set.

This is applicable only for Format 2.

Comments

CYJOIN and CYSYM Bulk Data Entries are required in cyclic symmetry analysis.
Supported analysis types include linear static (STATIC) and normal mode analysis (MODES). For normal mode analysis, currently only Lanczos (EIGRL) and Lapack-based dense (EIGRD) solvers are supported.
Two homologous CYJOIN entries should be defined respectively for both SIDE 1 and SIDE 2 of a segment. Each grid on a CYJOIN entry should be paired with a matching grid on the other entry. Mismatched grid pairs would result in loss of accuracy, and in such cases a warning that lists mismatched grids will be printed to the .out file.
The two cyclic boundaries of the modeled segment which are to be connected to adjacent segments are defined as SIDE 1 and SIDE 2. The positive direction of the axis of symmetry is defined such that SIDE 1 and SIDE 2 are numbered sequentially in the counter clockwise order about the axis.

Figure 1. Axis of symmetry and cyclic boundaries of the basic segment
The axis of cyclic symmetry is determined by the geometry and CD fields of the first pair of grids appearing on CYJOIN entries. Hence, the displacement coordinate systems (the CD field on GRID Bulk Data Entry) of the first grid pair should be consistent between the CYJOIN entries. This requirement could be easily satisfied by using a spherical or cylindrical coordinate system placed on the axis of symmetry. An example of consistent rectangular coordinate systems for CYJOIN is illustrated in Figure 2.

Figure 2. Illustration of consistency of the coordinate systems for CYJOIN
If PARAM, AXCYSYM, YES is present, the axis of symmetry will be defined by grids on the CYAX entry, and the restrictions in Comment 5 regarding the CD fields of grids on CYJOIN no longer apply. Refer to PARAM, AXCYSYM for more details.
At the segment interfaces, all components of displacement at GIDi are constrained to adjacent segments during the analysis, except those constrained by SPC, or assigned dependent by MPC, RBE2 and RBE3.