Design of Energy Scavengers Mounted on Rotating Shafts
  In this paper, a novel energy scavenger is proposed. The scavenger consists of a cantilever beam on which piezoelectric films and a mass are mounted. The mass at the tip of the beam is known as the proof mass and the device is called either an energy scavenger or a beam-mass system. The beam-mass system is mounted on a rotating shaft, where the axis of the shaft is horizontal. A single-degree-of-freedom (SDOF) mathematical model is derived for the scavenger and its properties are carefully examined. From the model, it becomes clear that the rotation of the shaft and gravity cause both parametric excitations and exogenous forces which make the beam-mass system vibrate. Guidelines are provided as how to choose the scavenger parameters in order to have it resonate. Examples are given to illustrate the performance of the proposed scavenger. 
S. M. Shahruz and V. Sundararajan