A Shear-Mode Energy Harvesting Device Based on Torsional Stresses

The shear-mode of a piezoceramic material offers improved energy harvesting potential as compared to other modes. This paper presents a concept of using torsional stresses induced by nonrotational vibrations in an energy harvesting device to produce electrical power. A finite-element model of this concept is presented to illustrate the principle and a prototype is demonstrated to validate the design. This prototype harvester is found to be capable of producing a maximum power of 0.57 mW at its resonant frequency of 620 Hz with a base acceleration of 1 g in amplitude. When compared to conventional cantilever harvester designs, this torsion-based harvester is found to suffer from fewer electrical power losses and has a greater potential in producing high power outputs.