Experimental and numerical investigation of energy harvesting from double cantilever beams with internal resonance

Abstract

Conventional harvester systems usually have linear behavior. One of the great matters in these systems is that energy is harvested in a low frequency bandwidth. In this study, double cantilever beams connected at the end through a linear spring are used for energy harvesting. The bimorph piezoelectric patches are attached to the top beam by using double-sided tapes for energy harvesting. A pair of magnets is utilized for adding a nonlinear effect to the system. One of the magnets is mounted at the end of the bottom beam, and the other one is placed on the system’s base. The whole system is designed based on the internal resonance phenomenon. The system’s vibration equations are derived by using the assumed modes method and solved with the numerical solution. Two cases are investigated, including the absence and the presence of the magnetic force. When the magnetic force exists, the effects of nonlinearity and internal resonance on the energy harvesting are investigated and the results are compared to the case when the magnetic force does not exist, which has a linear behavior. To validate the results, a test rig has been designed and fabricated for experimental studies. Experimental results show that the simulation results are in good agreement with the experimental data. The obtained results show that energy is usually harvested in a broader frequency bandwidth when the magnetic force exists compared to when it does not exist. However, when the magnetic force exists, peak voltage can be higher or lower than the case that the magnetic force does not exist. It depends on the system’s parameters.