Free Balls in a Non-rotating Track Can Mitigate Rotor Vibration

Vibration is an undesired response that increases the dynamic loads in rotor systems. The current study introduces a new design for a ball-in-track nonlinear energy sink (BIT-NES) able to mitigate rotor vibration. The proposed BIT-NES consists of a ball moving freely in a non-rotating circular track. A ball bearing is placed between the NES track and the primary rotor in order to prevent their rotation as one part. The relative rotation between the track and the rotor is a considerable change in the developed design compared to a typical automatic ball balancer. A test rig equipped with displacement sensors for the measurement of rotor vibration is used to test the developed BIT-NES over different angular speeds. Comparing the vibration amplitude of the primary rotor with and without the BIT-NES demonstrates the suppression effect of the absorber. Contrary to the typical automatic ball balancer that reduces rotor vibration only at high angular speeds beyond the critical speed, the advanced BIT-NES works at a wider speed range, including the small angular velocities below the rotor critical speed. Following this study that validates the effect of the modified BIT-NES in mitigating rotor vibration, parametric studies done on the influence of changing the design main parameters will be presented in an extended version.