Enhancing And Controlling Parametric Instabilities In Mechanical Systems

We gain new fundamental insights on parametric instabilities that are at the heart of many physical phenomena from the dynamic buckling of slender structures in periodic compression to the emergence of Faraday waves or the spontaneous symmetry breaking in Floquet time crystals. Combining theoretical models and precision desktop experiments, we explain how to periodically vary the evolution function of a dynamical system to enhance and get control on parametric instabilities. We show on a proof of concept that is an electromagnetic pendulum: (i) how to observe extremely high orders of parametric resonance, even in the presence of dissipation, (ii) how to trigger and efficiently sustain the natural vibrations of an oscillator. The presented concepts being universal, they could offer new dynamical functionalities in various fields and at any scale, from actuation in soft robotics to vibrational motions in microelectromechanical resonators. (C) 2021 Elsevier Ltd. All rights reserved.