Harvesting weak vibration energy by amplified inertial force and multi-stable buckling piezoelectric structure

One of the main challenges in vibration energy harvesting is to improve the efficiency for low-frequency and weak ambient vibration. A desired harvester should own a broadband working frequency and large-amplitude under weak excitation. In this paper, a novel harvester is proposed, which can enhance the energy harvesting performance for weak ambient vibration by amplified inertial force and multi-stability. This harvester is constituted of an inertial mass, two piezoelectric buckled beams and two linkages. Under external excitation, the inertial force produced by inertial mass is amplified and acts on the piezoelectric buckling beams via linkages, by which the amplified inertial force can drive the piezoelectric buckling beams to execute inter-well oscillation densely and generate high output power over a broadband frequency. Furthermore, the harvester possesses a super-harmonic vibration characteristic and can realize the frequency up-conversion effect, so the low-frequency excitation can excite the high-frequency vibration of piezoelectric beam and increase the output. The influence of the beam's buckling level is studied through potential energy analysis. The output performance and nonlinear dynamic characteristics are studied under different types of excitations, i.e., the frequency sweeping, harmonic and random excitations. The validation experiment was carried out. The results prove that the harvester owns the super-harmonic characteristic and can execute snap-through motion under weak random excitation. Thus it can produce a larger output for weak excitation.