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forward/backward whirl

i am trying to model a forward/backward whirl for a engine blade at various rpms. how do you model this in nx ? thanks


Re: forward/backward whirl

Run a rotordynamics analysis in SOL 107-112.


See the Rotordynamics User's Guide for more information.

Re: forward/backward whirl

where can i get the user's guide ?

Re: forward/backward whirl

The Rotor Dynamics Users Guide is in the NX Nastran documentation. If this is a bundled NX installation, see the NX docs and navigate to CAE, NX Nastran, NX Nastran Rotor Dynamics User's Guide.


NX Nastran documentation is also available online at:

Re: forward/backward whirl

i have run the rotordynamics analysis using SOL 107. now i need to extract first and second pair of natural frequencies for
1. various rpms 0,2000,4000 etc. for both forward & backward whirl

how do i do this ?

Re: forward/backward whirl

This data should be printed inthe .f06 file.


If you include PARAM, ROTCSV in your deck, Campbell diagram data is written to a .csv file that can be opened in a spreadsheet for plotting.


See Chapter 4 (Interpretation of Rotor Dynamics Output) of the Rotordynamics User's Guide. Section 4.3 covers the .csv output.


We also provide a journal (%UGII_BASE_DIR%\UGOPEN\SampleNXOpenApplications\.NET\CAE\CampbellCsvToAfu) to process this .csv file and create AFU records that can be plotted in the NX Function Navigator.

Re: forward/backward whirl

also, this is a cyclically symmetric modal analysis. a rotating, hollow shaft is built in at one end and has a thin, rigid disc attached at the other. 1/40th of the rotor is modelled using brick elements. how do i assign cyclic symmetry boundary conditions to this model, and where do i apply them. thank you.