THESIS ACTIVE FEEDBACK DAMPER FOR MULTIRESONANT STRUCTURES

摘要

This thesis presents a theoretical and experimental analysis of an active feedback system for controlling mechanical vibrations of multi-resonant structures. A velocity transducer, an amplifier and a vibration generator are connected in negative feedback to generate a damping force proportional to the feedback loop gain, thus reducing resonant vibrational motion. Design of a stable system using commercially available components is carried out for the case of a 48 inch uniform beam of 1" by •2" section. Generality of the technique is demonstrated by also applying the design to a 21 inch diameter cylindrical shell. Maximum velocity reduction is found to be proportional to the undammed mobility of the structures and is limited by stability conditions imposed on the feedback gain. Damping of beam modes lying below 10 kc is achieved with reductions for the highest mobility resonances being 25-30 decibels.