Active Control of Flexural Vibrations in Beams

The feasibility of using piezoelectric actuators to control the flexural oscillations of large structures in space is investigated. Piezoelectric actuators have the advantage of exerting localized bending moments. In this way, vibration is controlled without exciting rigid body modes in the structure. The actuators are used in collocated sensor∕driver pairs to form a feedback control system. The sensor produces a voltage that is proportional to the dynamic stress at the sensor location, and the driver produces a force that is proportional to the voltage applied to it. The analog control system amplifies and phase shifts the sensor signal to produce the voltage signal that drives the driver piezoelectric. The feedback control system is demonstrated to increase the first mode damping in a cantilever beam by up to 85%, depending on the amplifier gain. An analytical model of the control system is developed. The estimated and measured vibration control compare favorably. A simulated free‐free beam is fabricated and instrumented with a distribution of piezoelectric sensor∕driver pairs. The purpose is to evaluate the damping efficiency of the control system when the piezoelectrics are not optimally positioned at points of high stress in the beam. The control system is found to reduce the overall vibration response to impact by a factor of two.