A rotational impact energy harvester utilizing the centrifugal softening effect

Rotational energy harvesting has received massive attractions due to the abundance and availability of rotational motions in ambient environments. This paper considers a rotational impact energy harvester by utilizing the static instability of a centrifugal softening beam. During the rotation, two rigid piezoelectric beams are impacted by the centrifugal softening driving beam to generate electric energy. When the rotational frequency is increased, with the centrifugal effect, the amplified relative motion between the driving and generating beams significantly contributes to the increase of the impact force and in turn the output power. The theoretical model is developed and used for numerical simulation. It is shown that the output voltage can be significantly improved with the centrifugal softening effect. Furthermore, the impact force is demonstrated to prevent the driving beam from continuously deflecting and suffering the mechanical failure.