Controlled damping of elastic vibration by means of motion of internal masses

An effective method for damping elastic vibration of load-carrying structures by means of a dynamic absorber is suggested. The control law is defined as a linear feedback with respect to the absolute displacement and velocity of the load and the displacement and velocity of the absorber body relative to the load. Two methods of adjusting the feedback gains are compared. One method is based on the maximization of the system degree of stability. It provides a rapid damping but can lead to unacceptably large displacement of the absorber body if its mass is small compared with that of the load. In the second method, the feedback with respect to the variables of motion of the load is weaker, which decreases the damping rate but reduced the maximum displacement of the absorber body. An optimal combination of these two damping modes makes it possible to provide an acceptable performance of the damping process