The effect of inherent nonlinearities in coupled piezo-magneto-electric vibration energy harvester

This work deals with the experimental observation of inherent material nonlinearities occurring due to the magnetic plucking in a nonlinear piezoelectric vibration energy harvester. A piezoelectric cantilever is actuated via magnetic forces with a robotic arm at different constant velocities, in the range of 0.5 m/s - 2.5 m/s. The Fast Fourier Transforms of the voltage, in open circuit conditions, show that as the impulsiveness of the magnetic force increases, the peak of the first bending mode of the beam shifts toward lower frequencies. Such phenomenon should be taken into account for a reliable simulation and thus for the evaluation of the optimal electrical condition of power extraction.