**CYCFREQ**, * Option*,

`Value1`

`Value2`

`Value3`

`Value4`

`Value5`

Compatible Products: – | – | Premium | Enterprise | Ent PP | Ent Solver | –

`Option`

One of the following options:

**AERO**—

Specify the array containing the aerodynamic damping coefficients.

`Value1`

—

The name of the array containing the aerodynamic stiffness damping coefficients.

**BLADE**—

Blade information required for a mistuning analysis.

`Value1`

—

The name of the nodal component containing the blade boundary nodes at the blade-to-disk interface. Also include boundary nodes at any shroud interfaces.

`Value2`

—

The name of the element component containing the blade elements.

`Value3`

—

The number of blade modes to include in the CMS reduction.

`Value4`

—

The lower bound of the frequency range of interest. This value is optional.

`Value5`

—

The upper bound of the frequency range of interest. This value is optional.

**DEFAULT**—

Set the default cyclic harmonic solution settings.

**EO**—

Excitation engine order.

`Value1`

—

The value of the excitation order, which must be an integer. The loadings on the other sectors will be related to the loading on the basic sector based on the engine order phase shift.

**MIST**—

Mistuning parameters.

`Value1`

—

The type of mistuning:

**K**—

Stiffness (frequency) mistuning

`Value2`

—

The name of the array containing the stiffness mistuning parameters.

**MODAL**—

Specifies if a damped modal analysis should be performed on the reduced system.

`Value1`

—

On/Off key.

**0 (OFF or NO)**—

No modal solution. Perform the harmonic solution.

**1 (ON or YES)**—

Perform a damped modal analysis of the reduced system in order to obtain the complex frequencies. The harmonic solution is not performed.

`Value2`

—

Number of modes for the damped modal analysis.

`Value3`

—

The beginning, or lower end, of the frequency range of interest (in Hz).

`Value4`

—

The ending, or upper end, of the frequency range of interest (in Hz).

**RESTART**—

Defines the point at which to restart the harmonic analysis.

`Value1`

—

The restart point:

**OFF**—

No restart (default)

**SWEEP**—

Restart for a new frequency sweep range (

**HARFRQ**)**MIST**—

Restart for new mistuning parameters (new mistuning arrays)

**USER**—

Causes the program to call for a user-defined solution.

`Value1-5`

—

Values passed down to the user-defined solution.

**STATUS**—

List the harmonic solution option settings active for the cyclic model.

The program solves a cyclically symmetric model (set up via
the **CYCLIC** command during preprocessing) at the
harmonic indices specified via the **CYCOPT** command.

When * Option* = AERO, the
aerodynamic coefficients are specified in a 5×(N×r) array (

where:

= the i^{th} interblade phase angle (IBPA) |

= the m^{th} vibrating blade mode |

= the n^{th} blade mode generating the pressure oscillations |

and = the real and imaginary coefficients. |

One aerodynamic damping coefficient must be specified for each IBPA (equal to the number of blades) while keeping m and n constant.

The following table shows how the IBPA index () relates to other quantities for a system with 22 blades:

IBPA Index () | Nodal Diameter | IBPA (degrees) |
---|---|---|

0 | 0 | 0 |

1 | 1 | 16.36 |

20 | -2 | -32.73 |

21 | -1 | -16.36 |

The **CYCFREQ**,AERO command is only valid if
**CYCFREQ**,BLADE is also specified. The blade mode numbers, m and n, are
relative to the values kept in the **CYCFREQ**,BLADE command.

For constant (frequency-independent) mistuning,
the stiffness parameters are specified in an N×1 array (***DIM**) where N is the number of blades.

For stiffness mistuning, each row entry
represents the deviation of Young’s modulus from nominal, (or equivalently, the ratio of the frequency deviation
squared). Each frequency can also be independently mistuned, in which
case the array is N×M, where M is the number of blade frequencies
(* Value3* of

The USER option activates the solution
macro **CYCMSUPUSERSOLVE.MAC**. The normal solution
is skipped. You may implement your own mistuning solution using APDL
and APDL Math operations, or call your own program for the solution.

The **CYCFREQ** command is valid in the preprocessing
and solution stages of an analysis.

The **CYCFREQ**,MODAL,ON
command writes modal frequencies to the output file. No other postprocessing
is available for this modal solve.

When using **CYCFREQ**,RESTART, only mistuning parameters or frequency range
may be changed. All other changes in parameters are ignored. This
type of restart can only be performed by exiting the current mistuning solution using
**FINISH** and re-entering the solution phase using **/SOLU** and
then calling the desired **CYCFREQ**,RESTART command.

To learn more about analyzing a cyclically symmetric structure,
see the *Cyclic Symmetry Analysis Guide*.