The objective of the proposed work is to gain an improved understanding of the dynamic response and performance of systems that utilize multiple vibration absorbers and to distill this knowledge into design guidelines. Of specific interest are centrifugally driven pendulum absorbers that are used for reducing torsional vibrations in rotor applications. These absorbers consist of masses that are suspended from the rotor in such a manner that their motion counteracts the effects of fluctuating torques that act on the rotor. This study employs both analysis and experimentation of such absorbers. The analysis focuses on mathematical modeling and the application of predictive techniques, including perturbation methods and symmetric dynamic bifurcation theory. The desired performance of absorbers is achieved by proper selection of design parameters that are included in the formulation. Experimentation is carried out on an existing torsional vibration facility that allows for control of the mean rotor speed and fluctuating torque components. Specific topics being investigated include: the application of absorbers to reduce vibrations in rotating beams, the use of absorbers for shake reduction, the avoidance of localization in absorber systems, absorbers for multi-harmonic excitation, and the transient performance of absorbers. By systematic investigation of nonlinear behavior, instabilities, and vibration localization, this study offers strategies for avoiding effects that limit the performance of absorber systems, and the results are used to provide useful recommendations for implementation of systems of absorbers in rotating systems. *******************************************************************
