A low-frequency, wideband quad-stable energy harvester using combined nonlinearity and frequency up-conversion by cantilever-surface contact

This paper proposes models and experiments of a wideband piezoelectric vibration energy harvester with a quadruple-well potential induced by the combined nonlinearity of cantilever-surface contact and magnetoelasticity. The cantilever-surface contact introduces frequency up-conversion mechanism into the present energy harvester and provides favorable mechanical properties such as minimal moving parts, low frictional losses and high shock resistance. The magnetoelasticity, combined with the cantilever-surface contact, can make the present energy harvester exhibit multi-stability, ranging from mono-stability to quad-stability. The formation mechanism of this multi-stability is investigated by a static bifurcation analysis to the harvester's mathematical model. Dynamic responses of the present energy harvester with a quadruple-well potential are explored by numerical simulations and validated by experiments. The results show that the combined nonlinearity can not only improve the efficiency of electrical power transfer under low intensity excitations, but also extend the wide operating band of harvester to low frequencies.