Today, dynamic absorbers are widely used to control vibrations of the systems that are being excited by the harmonic forces. In this paper, the usage of the magnetic force as virtual dynamic absorber for vibration control in rotary systems is investigated. In order to examine this new method, two different types of passive dynamic absorber systems are applied to control imbalanced Jeffcott rotor vibrations. In the first type of the absorber system, damper is located between the absorber mass and the disk and in the second type, it is located between the absorber mass and the ground. Then, the optimal parameters of absorber system, stiffness and damping have been analytically achieved by using two fixed points theory. Moreover, for further reduction of the vibration amplitude, combined paths have been designed for rotor frequency response. Finally, in order to evaluate the obtained results, the experimental data of our virtual dynamic absorbers were compared with simulation results and it is found that the vibration amplitude of rotor was efficiently limited in this case. Furthermore, the second type of the absorber system with equal mass ratio to the first type of the absorber system was more efficient than the first one in reduction of the amplitude of vibrations. Our findings show that the second absorber transfer more force than the first one since the second absorber connects chasis of system with damper. Therefore, it is recommended to apply the first absorber after the first resonance.

The main sources of the vibration in rotor dynamic systems are unbalanced masses and manufacturing defects of bearings used in the rotor system. In this study, magnetic absorber as a new method brings the rotor system out of resonance state by applying a dynamic absorber system force and creating two new natural frequencies. This study virtually reconstructed magnetic absorber controller software as a combined active and passive dynamic absorber to reduce vibration amplitude, efficiently. In this approach, combined routes are defined for the rotor frequency response, so that the optimal values of the parameters of dynamic absorber system are calculated using H ∞ method and maximum damping for frequencies lower and higher than resonance frequencies, respectively. The results confirm that transient response overshoot is less, and transient response attenuation is more in maximum damping method. Hence, the controller system easily recognizes initial overshoots and determines the parameters of the dynamic absorber system in accordance with maximum damping state if it is struck at any rotor frequency and any rotation angle. It is also observed that for all rotor rotation frequencies, the system overshoot reduces in comparison with H ∞ method by using this control method. *