Becker J., Gaul L.

Reduction of structural vibrations are of major interest in mechanical engineering for reducing sound emission, improving accuracy of machines and increasing durability. Besides optimal passive design, this problem can be tackled by structural control concepts, which become more and more important as lightweight construction evolves. In this contribution, semi-active control of friction dampers is presented. In contrast to purely active control strategies, semi-active control algorithms have the advantage of being intrinsicly stable and possessing relatively low energy consumption. Friction damper elements are used in order to reduce structural vibrations, the normal force of frictional interfaces is applied by piezoelectric stack actuators and controlled accordingly to the measured structural vibrations for optimal damping. The control design is based on models of the structural dynamics, that incorporate the frictional effects at the contact interfaces by use of zero-thickness contact elements. Model reduction is applied for efficient simulation of passive and semi-active controlled mechanical structures with frictional interfaces. The model can furthermore be used for optimal placement of the friction dampers on the structure. Simulation and experimental results for a generic test structure are presented.