Centrifugal pendulum vibration absorbers (CPVAs) are devices designed to reduce torsional oscillations in order-excited rotational systems. The focus of this research is to develop and test algorithms that allow one to determine the absorber motion (amplitude and phase) using the readouts from an accelerometer attached to the absorber and an encoder sensing the rotor motion. This requires a detailed analysis of the pendulum kinematics, which depends on the path followed by the absorber mass and the rotation of the absorber relative to the rotor. The absorber kinematics are governed by a differential equation that relates the absolute absorber acceleration (measured signal from an accelerometer) and the rotor speed and acceleration (measured signal from an encoder), to the motion of the absorber relative to the rotor. This differential equation is solved approximately using a harmonic-balance method, based on assumptions regarding the significant harmonics in the rotor and absorber dynamics. The resulting approximations are tested using numerical simulations of the equations of motion, as well as in experiments in which the approximated absorber motions are compared to direct encoder measurements of the response. Both simulations and experiments show that absorber motions are successfully estimated from measurements of the absolute acceleration of the absorber and rotor motions, although some deviation is apparent when absorber motions have large amplitudes. This approach will allow test engineers to validate models that predict and assess absorber performance in rotational systems (e.g., automobile engines), which will improve confidence in the absorber design process.
Read
