Nonlinear Feedback Excitation for System Interrogation by Bifurcation Morphing

This paper demonstrates a novel system-interrogation method based on observing the morphing of bifurcations and the postbifurcation dynamics through both experimental and numerical methods. A sensing cantilever beam is built with lead-zirconate-titanate patches symmetrically bonded to both sides of its root. A desired bifurcation in the dynamics of the beam can be induced by applying a nonlinear feedback excitation to the beam. The nonlinear feedback excitation requires the active measurement of the dynamics and a feedback loop, and it is generated by applying the voltage (resulting from a nonlinear feedback) to the piezoelectrode. Also, a finite element model is used to design the nonlinear feedback excitation and to predict the response of the sensing beam. Numerical simulations and experiments are performed and compared that demonstrate the effectiveness and high level of sensitivity of the novel approach to detect very small amounts of mass added at the tip of the beam.