Application of piezoelectric elements to semi-adaptive dynamic eleminator of torsional vibration

The paper is concerned with the problem of vibration damping in a torsional system by application of dynamic eliminator equipped with piezoelectric elements. Piezoelectric elements are capable of changing their overall dimensions when exposed to external electric field. If shaped in the form of rings and placed side by side they create a cylindrical shell the radius of which can be controlled by a voltage signal according to the converse longitudinal piezoelectric effect. The dynamic vibration eliminator with such a piezoelectric cylinder mounted in the space filled up with a viscous medium coaxially to the internal cylindrical surface grinded inside of the eliminator housing can adjust its damping coefficient by changing dimensions of the oil gap by applying the voltage to the piezoelectric elements. This property enables the eliminator to adapt its damping to variable excitation frequency so that the optimum damping constant can be obtained. This protects the vibrating system from, what is characteristic for typical dynamic eliminators, disadvantageous growth of the vibration amplitude outside of the resonant zones.