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

A highly efficient simulation technique for piezoelectric energy harvesters

This paper presents a new numerical technique which is aimed at obtaining fast and accurate simulations of piezoelectric beams, used in inertial energy harvesting MEMS. The execution of numerical analyses is greatly important in order to predict the actual behaviour of MEMS device and to carry out the optimization process on the basis of Design of Experiments (DOE) techniques. In this paper, a refined, yet simple, model is proposed with reference to the multi-physics problem of piezoelectric energy harvesting by means of laminate cantilevers. The proposed model is calibrated and validated with reference to 3D finite element analyses

Numerical and experimental evaluation of the magnetic interaction for frequency up-conversion in piezoelectric vibration energy harvesters

The purpose of this work is to improve the modelling process for the application of permanent magnets in a frequency up-conversion (FuC) mechanism for piezoelectric energy harvesters. More specifically, the aim is to avoid the burdensome finite element analyses (FEA) in the framework of electromechanical devices design. The analytical calculations are compared with experimental tests conducted by an ad-hoc set up and with FEA. After investigations on the interaction, an application of FuC mechanism is proposed on a meso-scale case study in which a low frequency seismic mass (LFM) interacts non-linearly, due to magnetic field, with an high frequency piezoelectric vibration energy harvester (PVEH). Numerical simulations have been carried out in the time domain (step-by-step analysis) under a harmonic low-frequency input acceleration signal. The peculiar behavior, due to non-linear dynamics, is investigated in both the repulsive and the attractive configurations of the magnets. The results confirm the effectiveness of magnetic FuC and show that the repulsive case allows the device to recover a larger amount of energy than the attractive configuration

On the application of piezolaminated composites to diaphragm micropumps

This paper deals with the numerical simulation of piezolaminated microplates adopted as actuators in micropumps. The performances of piezoelectric actuation is critically assessed by means of comparisons with devices based on the electrostatic force