Modeling and Analysis of Piezo-Elastica Energy Harvester in Computer Hard Disk Drives

In this paper, design and analysis of an energy harvester named piezo-elastica energy harvester (PEEH) to harvest wasted mechanical energy generated by flex cable kinetic and vibratory motions are presented. A coupled piezo-elastic model is developed for the harvester with focus given to understanding piezoelectricity generated by its PVDF layer over its underlying largely deformed flex cable elatica structure. Design for manufacturing for the proposed harvester is detailed in this work. Numerical finite element simulations and laboratory measurements using noncontact laser interferometry validate the mode with respect to the PEEH's profiles, natural frequencies and mode shapes as well as electric energy generated resulted from flex cable's dynamics. It is observed that about 25% of the power consumed by disk drive's voice coil motor can be harvested by the proposed design. Among harvested energy, it is found that 58% comes from significant change of PEEH's profile when rotary actuator swings between disk's outer diameter and inner diameter regions, 33% from PEEN's 2nd bending mode, and 9% from its 1st bending mode. The work presented in this paper suggests the possibility of scavenging and converting flex cable's mechanical vibrations and dynamics into electrical form for power conservation inside computer hard disk drives.