A Subharmonic Vibration Absorber for Rotating Machinery

We demonstrate a dynamic vibration absorber system which can be used to reduce speed fluctuations in rotating machinery. The primary system is modeled as a simple rotating disk, and the idealized absorber system consists of a pair of equal point masses which are free to move along identical, prescribed paths relative to the disk. The unique features of the proposed arrangement are that the absorbers are tuned to one-half of the frequency of the applied torque and, more importantly, that they are effective in the fully nonlinear operating range. These absorbers can, in the undamped case, exactly cancel a pure harmonic applied torque of a given order without inducing any higher harmonics, thus rendering a perfectly constant speed of rotation. A perturbation method is used to extend the results to the small damping case and to investigate the dynamic stability of the desired motion. Simulations are used to verify the analysis and to demonstrate the effectiveness of the device.