# HARMONICS

I/O Options EntryUsed to specify the solution harmonics to be used in cyclic symmetry analysis.

## Format

HARMONICS = option

## Example 1

Using SET definition in the Bulk Data section.
HARMONICS = 26
SET, 26, MODE
+, 0, 1, 2, 6, 10

## Example 2

Using SET definition in the Case Control section.
HARMONICS = 26
SET 26 = 0, 1, 2, 6, 10

## Definitions

Argument Options Description
option <ALL, SETID>
ALL (Default)
All harmonics will be used.
SETID
Set identification number.
The referenced SET lists the indices of the harmonics to be used.

(Integer > 0)

1. When the HARMONICS I/O Option is not present, HARMONICS=ALL will be set by default in cyclic symmetry analysis.
2. The SET definition referenced by HARMONICS should be a set of TYPE = MODE.
3. The harmonic indices are supposed to be non-negative and must be no greater than (NSEG is defined in the CYSYM Bulk Data Entry).
If NSEG is odd:(1)
$\left(\frac{NSEG-1}{2}\right)$
If NSEG is even:(2)
$\left(\frac{NSEG}{2}\right)$
4. In general, lower harmonics lead to higher contribution. Table 1 summarizes the effect of using ALL and SETID for the supported analysis types.
Table 1.
Analysis Type HARMONICS = ALL HARMONICS = SETID
Linear Static Analysis with non-cyclic loading (SEGID = blank in LOADCYN) This is recommended to obtain same result as the full model. Removing some harmonics could lead to loss in accuracy.

For large models, this could help with reduction in the CPU time.

Linear Static Analysis with cyclic symmetric loading In this case, only the 0th Harmonic will be used, and all other harmonics will be disregarded.

If SETID is used, the 0th Harmonic must be a part of the set. As long as this requirement is met, HARMONICS=SETID will yield the same result as HARMONICS = ALL.

Normal Modes Analysis This is recommended to obtain same result as the full model. This is useful when only certain harmonic patterns are desired.

Removing some harmonics will only lead to some missing mode shapes, without any loss in accuracy.