Active Damping of Vibrations of a Lightweight Beam Structure - Experimental Results

Abstract

Lightweight beam structures are used in various fields of applications, e.g. in aerospace industry and civil engineering. The natural damping of such structures is often very small which may result in a reduced lifetime. One possibility to increase the damping is the use of active damping devices to apply state-dependent moments and/or forces to the mechanical structure. In this contribution, a single axial force is applied to a cantilever beam by using a string along with a piezoelectric actuator. To introduce artificial damping to the lateral vibrations of the beam, a nonlinear parametric feedback control law is used which is based on axial velocity feedback of the tip of the beam. A test rig was built where the lateral vibrations of the beam are measured with a laser-measurement device, and a piezoelectric sensor measures and indicates the actual force in the string. Both signals are feed into the realtime-controller, which calculates the corresponding control signal for the piezoelectric actuator. The experimental results show highly increased damping capabilities compared to the uncontrolled system.