Energy harvesting from human motion by impact-excited bistable buckled beams

Abstract

Energy harvesting from human motion faces with challenges including low-frequency and non-harmonic excitation. This paper presents a novel impact-excited energy harvesting system using a bilayer structure which is composed of a buckled piezoelectric beam and a rubber plate with a certain spatial separation. When the rubber plate is excited by the low frequency human gait impulse, it would touch the buckled piezoelectric beam and trigger the snap-through vibration of the beam through the up-conversion mechanism. The electromechanical response of the proposed nonlinear energy harvesting system under the standard low-frequency and non-harmonic gait excitation is studied by numerical simulations. The influences of the geometrical and physical parameters including the mechanical properties of the materials, separation distance of the bilayer structure and the excitation parameters are examined respectively. The appearances of the chaotic and periodic responses of the energy harvesting systems with different physical parameters are illustrated by the phase portraits, and time-domain images. Compared with intrawell and chaotic oscillations, high energy periodic interwell vibrations are demonstrated to greatly improve the energy harvesting performance. The results of the parameter analysis can be used to optimize the energy harvesting structure.