During the simulations there found pairs of frequencies very close as values. These were associated with identical modes that are in opposite directions.
An interesting fact that was found was associated with the transversal mode shapes of the stator and of the rotor. They have the tendency to vibrate in opposite direction and so it is developed the danger of hit each other.
The recorded values of the experimental modal analysis are very close with the values obtained by finite element method despite the damping was not used in material model (see Table II).