Modal structure of centrifugal pendulum vibration absorber systems with multiple cyclically symmetric groups of absorbers

This work studies the symmetry breaking effects on the vibration mode structure of centrifugal pendulum vibration absorber (CPVA) systems when multiple groups of absorbers are used. An absorber group is a set of equally spaced, identical absorbers. Absorbers within a group are cyclically symmetric while the entire system is asymmetric because the groups have no pre-defined relative angular spacing. One rotational and two translational degrees of freedom for the rotor and a single arclength degree of freedom for each absorber are considered in the planar model. The well-defined structure of the vibration modes is obtained by analytical and numerical investigations of the associated eigenvalue problem. This vibration mode structure is similar to that for CPVA systems with equally spaced, identical absorbers. Thus, the disrupted symmetry from multiple absorber groups does not destroy the vibration mode structure resulting from the cyclic symmetry within each group. The critical speeds and flutter instability of the system are investigated.