Vibration absorption has been a very attractive way of removing oscillations from structures under steady harmonic excitations. There are many common engineering applications yielding such undesired oscillations. Helicopter rotor vibration, unbalanced rotating power shafts, bridges under constant speed traffic can be counted as examples. | 14 Active Vibration Absorption and Delayed Feedback Tuning Nejat Olgac University of Connecticut Martin Hosek University of Connecticut Introduction Delayed Resonator Dynamic Absorbers The Delayed Resonator Dynamic Absorber with Acceleration Feedback Automatic Tuning Algorithm for the Delayed Resonator Absorber The Centrifugal Delayed Resonator Torsional Vibration Absorber Multiple Frequency ATVA and Its Stability Synopsis Stability Analysis Directional Stability Chart Method Optimum ATVA for Wide-Band Applications Introduction Vibration absorption has been a very attractive way of removing oscillations from structures under steady harmonic excitations. There are many common engineering applications yielding such undesired oscillations. Helicopter rotor vibration unbalanced rotating power shafts bridges under constant speed traffic can be counted as examples. We encounter numerous vibration absorption studies starting as early as the beginning of the 20th century to attenuate these vibrations Frahm 1911 den Hartog et al. 1928 1930 1938 . The fundamental premise in all of these works is to attach an additional substructure the absorber to the primary system in order to suppress its oscillations while it is subject to harmonic excitation with a time varying frequency. A simple answer to this effort appears as passive vibration absorber as described in most vibration textbooks Rao 1995 Thomson 1988 Inman 1994. Figure depicts one such configuration. The absorber section is designed such that it reacts to the excitation frequency above much more aggressively than the primary does. This makes the bigger part of the vibratory energy flow into the absorber instead of the primary system. This process complies with the literary meaning of the word absorption of the excitation energy. Based on the underlying premise there has been strong pursuit of new directions in the field of vibration absorption. A good survey paper to read in this area is Sun et
