Sheldon Imaoka
Ansys Employee

Hi mohammedlaminemekhalfia,

Usually, I believe that Campbell Diagrams are created when you have the disc and shaft - how would you get forward/backward whirls if you are just modeling and constraining the disc?  Also, the procedure usually assumes axisymmetric geometry (since the rotating part(s) are not actually rotating).

The Ansys documentation has more details on the assumptions and procedures related to generating Campbell diagrams, so please review that material.  (Under "Mechanical APDL" section, "Rotordynamics Analysis Guide")