The research of stiffness characteristics of active elements of harvester

This paper is dedicated to one part of research of human mechanical energy harvester. Harvesters produce electrical energy from human's kinetic energy. Harvesting energy from human body is particularly useful for military portable electronic equipment, life supporting implantable medical devices (IMD) and consumer electronic devices. As a basis of energy transformation piezoelectric crystal was used. Human body creates vibrations of very low frequency, but piezoelectric crystal has natural frequency of hundreds of hertz. This research is intended to adjust mechanical parameters of this harvester and define additional mechanical system parameters which will allow whole harvester became dynamically sensitive to human body vibrations. In this paper there were defined stiffness of real test sample of piezoelectric harvester part and defined characteristics of reduced moments of inertia for dynamical and further mathematical models. After obtaining these values, verification of experimental and theoretical results are presented. Experimental research was performed on specially created test rig using prepared test piece. Theoretical calculations were performed using Solidworks simulation software. Finally, results were compared and conclusions are drawn.