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.