Coupling nonlinearities investigation and dynamic modeling of a tristable combined beam rotational energy harvesting system

Abstract

Energy harvesting system is regarded as major units in self-powering of massive sensors of Artificial Internet of Things, whose mechanical dynamics play a crucial role in energy conversion efficiency and overall service performance. During rotational motion, periodic disturbances near resonant regions may lead to a large-amplitude oscillation of the harvesters. Due to the coupling effect of rotation and vibration, the distributions of mass and stiffness are related with local deformation and nonlinear rotational frequency in harvesting system, which are yet to be well understood and it is still an open issue. In this paper, a tristable combined beam rotational energy harvester is proposed to obtain higher energy conversion efficiency. Based on the extended Hamilton’s principle, a comprehensive coupling nonlinearities dynamic model is established with consideration of strain distributions, geometric nonlinearity, centrifugal effect, gravitation effect, and nonlinear rotational frequency. The effect of geometric nonlinearity and gravity on the synergistic transition and form mechanism of the tristable harvesting system is explored under the guidance of the static bifurcation, and the influence mechanism of the geometric nonlinearity and nonlinear rotational frequency on the mechanic and energetic characteristics of the system are thoroughly revealed. Numerical and experimental studies are performed to validate the effectiveness of the established model. Results show that geometric nonlinearity and nonlinear rotational frequency lead to a wider frequency bandwidth and a more complex inter-well snap-through motion. Meanwhile, the established model provides a theoretical fundamental framework of high-performance harvester’s design in large-amplitude complex excitation scenarios, which is conducive to control harvester in actual engineering applications.