Exploiting Nonlinearities in a Mechanical Energy Harvester by Employing a Novel X-Shaped Design

Increasing the efficiency of mechanical energy harvesters has attracted considerable attention in recent years. Due to their relatively low output power, it is very crucial to design them as efficiently as possible. Various studies have been conducted to investigate different approaches to increase the efficiency of mechanical energy harvesters. Increasing the system response bandwidth by introducing nonlinearities can aid in achieving this goal. In this paper, an X-shaped spring configuration is proposed for a vertical oscillator that provides the desired nonlinearity to the harvester. The preload in the oblique springs can act as an adjusting parameter to switch between different stability conditions. The system responses to harmonic excitation are investigated for various stability conditions, to highlight the effects of different nonlinearities on the system behavior. The results show that a specific nonlinearity should be tuned for each excitation input profile to achieve the highest output energy.