4. Rigid rotor model with four degrees of freedom

Let's now consider the integration of thrust and aerostatic bearings in a rotating machine, taking the case of a rigid rotor with four degrees of freedom and calculating the transfer functions. Thrust and aerostatic bearings are taken into account by using the models described above together with a rotor model. The rotor can behave either as a rigid solid or as an elastic beam. If its first natural pulsation is greater than the maximum rotation speed, the rotor can be considered as a rigid beam guided in rotation by two bearings and stopped in translation by a stop. It is then described by the four-degree-of-freedom model presented in reference