Dynamic characteristics of axial load bi-stable energy harvester with piezoelectric polyvinylidene fluoride film

In this paper, a nonlinear bi-stable energy harvester with a bulking beam is proposed. Its bi-stable characteristics can be realized by the structure. The characteristics of the piezoelectric energy harvester are tested under different conditions. In the experiment, high speed framing camera is used to capture the details of movement. It is found that similar characteristics occur at low frequency and high frequency, but the principles are not the same. The vibration amplitude is insufficient former when the frequency is low. Under high frequency conditions, the system is hindered by the reverse excitation when the system is about to enter the second steady state due to insufficient response time. In the experiment, the axial load is measured by the length of the buckling beam and the electronic scale. It is found that the axial load has great influence on the vibration amplitude of the harvester. The results show that the harvester changes from inter-well vibration to intra-well vibration when axial load changes from 0.4 N to 1.5 N. The inter-well vibration of the harvester occurs when the acceleration is 3.5 g, the vibration frequency is 15 Hz and the axial load is 0.4 N.