cycfreq#
- Mapdl.cycfreq(option='', value1='', value2='', value3='', value4='', value5='', **kwargs)#
Specifies solution options for a cyclic symmetry mode-superposition
APDL Command: CYCFREQ harmonic analysis.
- Parameters:
- 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.
- Value2
The name of the Mechanical APDL array containing the modal forces corresponding to the modes kept in the mode-superpostion analysis.
- 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.
Notes
The program solves a cyclically symmetric model (set up via the
CYCLICcommand during preprocessing) at the harmonic indices specified via theCYCOPTcommand.The aerodynamic coefficients are specified in a 5x(Nxr) array (
*DIM), where N is the number of blades and r can be any positive integer. Each column has the structure:where:
One aerodynamic damping coefficient must be specified for each
IBPA(equal to the number of blades) while keeping m and n constant.For constant (frequency-independent) mistuning, the stiffness parameters are specified in an Nx1 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 NxM, where M is the number of blade frequencies (Value3 of
CYCFREQ,BLADE). The entries in each row therefore correspond to the ratio of the mistuned frequency to the tuned frequency squared minus one:The
USERoption activates the solution macroCYCMSUPUSERSOLVE.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
CYCFREQcommand is valid in the preprocessing and solution stages of an analysis.The
CYCFREQ,MODAL,ONcommand 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.To learn more about analyzing a cyclically symmetric structure, see the Cyclic Symmetry Analysis Guide.