HARFRQ
HARFRQ, FREQB, FREQE, --, LogOpt, FREQARR, Toler
Defines the frequency range in a harmonic analysis.
FREQBFrequency (Hz) at the beginning of the
FREQBtoFREQErange (ifFREQE>FREQB). IfFREQEis blank, the solution is done only at frequencyFREQB(the central frequency of octave bands, whenLogOpt= OB1, OB2, OB3, OB6, OB12 or OB24).FREQEFrequency at end of this range. For non-logarithm spacing (
LogOptis blank), solutions are done at an interval of (FREQE-FREQB) /NSBSTP, ending atFREQE, and no solution is done at the beginning of the frequency range,FREQB.NSBSTPis input via the NSUBST command. See the EXPSOL command documentation for expansion pass solutions.- --
Reserved.
LogOptLogarithm frequency span. Solutions are done at an interval of (log(
FREQE) - log(FREQB)) / (NSBSTP-1), (NSBSTP>1). The central frequency or beginning frequency is used forNSBSTP= 1. Valid values are:OB1
—
Octave band.
OB2
—
1/2 octave band.
OB3
—
1/3 octave band.
OB6
—
1/6 octave band.
OB12
—
1/12 octave band.
OB24
—
1/24 octave band.
LOG
—
General logarithm frequency span.
FREQARRAn array containing frequency values (Hz). Combined with the tolerance argument,
Toler, these values are merged with values calculated based on the specifications fromFREQB,FREQE, andLogOpt, as wellNSBSTPon the NSUBST command andCluston the HROUT command. Enclose the array name in percent (%) signs (for example, HARFRQ,,,,,%arrname%). Use *DIM to define the array.TolerTolerance to determine if a user input frequency value in
FREQARRis a duplicate and can be ignored. Two frequency values are considered duplicates if their difference is less than the frequency range multiplied by the tolerance. The default value is 1 x 10-5.
Notes
Defines the frequency range for loads in the harmonic analysis (ANTYPE,HARMIC).
Do not use this command for a harmonic ocean wave analysis (HROCEAN).
When frequencies are user-defined, the array FREQARR must be
one-dimensional and contain positive values. User-defined frequency input is not supported for
the frequency-sweep Variational Technology method
(HROPT,VT ) or the harmonic balance method (HROPT,HBM).
This command is also valid in PREP7.
Example Usage
Centrifugal Impeller Analysis Using Cyclic Symmetry and Linear Perturbation
Rotordynamics of a Shaft Assembly Based on a Representative Model of Nelson-Vaugh Rotor
Modal and Harmonic Frequency Analyses of an Automotive Suspension Assembly Using CMS
Acoustic Analysis of a Viscothermal Resonator
Forced-Response Analysis of a Mistuned Bladed Disk with Aerodamping