The phenomenon of self-balancing of rigid rotors is well known and investigated for rotors with fixed bearings. However, in some technical devices the rotor performs complex motions. An example of such system is a computed tomography scanner. Its anode rotates very fast in the housing of the X-ray tube. At the same time the X-ray tube itself rotates rather slowly around the patient’s body. It is very important for CT scanner to keep the minimal possible level of vibrations in order to obtain good image quality. The objective is to investigate how and to which extent the self-balancing devices can be used for reducing vibrations in a planetary moving rotor.
The model to consieder consists of the rotor of mass M, which is fixed on the end of the rigid carrier. The other end of the carrier is elastically suspended with radial spring-dampers of a certain stiffness c and damping b. The carrier rotates around it’s point of suspension with a constant velocity Ω. At the same time the rotor rotates around its symmetry axis with a given velocity ω. Its centre of mass has an offset relative to the rotation axis. Two pendulum balancers of mass m, moment of inertia J and length r are placed on the rotation axis of the rotor.
The stationary solutions of the system and the passage through the resonanceare are investigated analytically using averaging technique for the strongly damped systems. Analytic results match very well with numeric simulations when the velocity of the planetary motion is sufficiently small.