Terfenol-D nonlinear vibration absorber

An active nonlinear vibration absorber scheme for flexible structures is de monstrated. The absorber exploits the nonlinear transduction of nonbiased T erfenol-D actuators. It uses a quadratic feedback control law and the "quad ratic" strain-field characteristic of a nonbiased Terfenol-D actuator to ac hieve a nonlinear coupling between the absorber and the forced structure. A saturation phenomenon is induced by tuning the frequency of the underdampe d second-order absorber to one-half that of the primary structure. As a res ult, the structural vibrations are greatly reduced. This type of control ha s been demonstrated previously using linear actuators; the nonlinearities h ave been introduced via the control algorithm. Here, we show that nonbiased Terfenol-D actuators can perform effectively the "squaring" operation, ins tead of the algorithm, and achieve similar results. We develop the theory and present experimental results for the control of t he first and second modes of a cantilever beam. We also consider applicatio n of the strategy experimentally when the forcing is due to a rotating imba lance. In this case, the excitation source is nonideal. Our results indicat e that the saturation-based control technique implemented with a Terfenol-D actuator constitutes an effective nonlinear vibration absorber.