Enhanced Stiffness Sensitivity in a Mode Localized Sensor Using Internal Resonance Actuation

In this paper, an enhanced stiffness sensitivity in a mode-localized sensor was demonstrated for 1:2 internal resonance (IR) for the first time. Two mode localized modes (anti-phase (AP) and in-phase (IP) modes, with frequencies around 2ω
r
) could be simultaneously coupled with the rotational mode (ω
r
) by a nonlinear interaction utilizing internal resonance (IR). When the nonlinear-actuated AP motion is coupled with the IP motion, an enhanced mode coupling can be observed at the IP mode. The concept was investigated by both theoretical model and experimental result. A balanced AP motion up to the jump frequency was generated under IR actuation. In contrast, a strong mode coupling was observed at the IP mode when the stiffness perturbation was introduced. By measuring the amplitude ratio of the IP mode for different stiffness perturbations, the stiffness sensitivity was found to be improved by an order of magnitude to 12400 /Δk/k.