Energy harvesting from gravity-induced deformation of rotating shaft for long-term monitoring of rotating machinery

Energy harvesting from rotating machines for self-powered sensor networks has attracted increasing attentions in the last decade. In this work, an energy harvester employing piezoelectric stacks for rotating machinery is proposed, which cannot only harvest kinetic energy from bending deformation of rotating shaft but also has the capability of rotor fault detection. The structure and working concept of the energy harvester are initially presented. Afterward, a theoretical model for the energy harvester is established to clarify its output characteristics. Then, vibration tests under different rotating speeds are carried out with a prototype mounted on a rotor test rig. The effects of electrical connections of piezoelectric stacks, rotor geometry, energy harvester location, and fastener preload on the output performance of energy harvester are evaluated. Finally, the applications of powering a scientific calculator and detecting typical faults of rotor systems including rotor crack and rub impact faults are demonstrated. Apart from fault detection capability, the proposed energy harvester has the advantages of long lifespan and causing little interference with the rotational motion, which overcomes the inherent deficiencies of commonly studied beam-type energy harvesters and manifest the potential of proposed energy harvester for the long-term condition monitoring of rotating machines.