Reduction of vibrational power in periodically supported beams by use of a neutralizer

Abstract The control of vibration by neutralizers (dynamic absorbers) is of considerable interest in practical engineering. The reduction of vibrational power transmission in a finite, periodic beam by the action of this kind of passive device has been examined theoretically and experimentally. Some interesting characteristics have been found. First, a group of resonance peaks within a propagation band can be reduced in level by using only one neutralizer, the number reduced depending on the number of bays and the location. Second, the necessary tuned frequency of the neutralizer is related to the first resonance frequency within the corresponding propagation band. When the neutralizer is attached at the same point as the excitation force acting upon the beam, then the optimum frequency ratio is greater than one, otherwise it is less than one. A composite neutralizer is recommended for beams with more than ten bays with the excitation force and the neutralizer not being at the same point on the structure. Data for experiments on a finite, periodic beam show good agreement with predicted results.