Periodic substructure for multi-frequency energy harvesting with single piezoelectric patch

In the present paper a novel periodic substructure is proposed that allows to obtain several eigenfrequencies in a given frequency range. Moreover, the position where the piezo bender is placed has the same mode of vibration for all these eigenfrequencies. The bender is therefore able to harvest energy at all these eigenfrequencies thus greatly improving the overall efficiency. The next step will be to introduce nonlinearities in the substructure to even further extend the range of frequencies at which energy is harvested.

Simple piezo benders are able to harvest energy almost only at their first natural frequency. Thus, their efficiency is good only in presence of harmonic excitation having frequency equal to their first natural frequency. In case of wide band excitation, instead, more complex solutions have to be sought for. In particular, various forms of nonlinearity have been investigated that allow to "bend" resonance peaks and thus convert kinetic energy into electric energy over a wider frequency band. Also harvester with more benders have been analyzed.