This paper presents the development of a bimorph piezoelectric cymbal energy harvester that is particularly useful for extracting energy from the vibrating systems of relatively high compressive load. The bimorph cymbal harvester can be used to charge a capacitor or a battery through the piezoelectric layers fitted within the metal end caps under repeated compression or deformation.
In this work, feasibility of a bimorph piezoelectric cymbal harvester in series operation is investigated through theoretical analysis and experimental validation. The bimorph cymbal uses a composite disc of two piezoelectric layers and a steel substrate between metal end caps.
Theoretical modeling to quantify the generated energy by using bimorph cymbal design is first conducted. A parametric study is then performed to optimize generated energy with the dominant design parameters influencing energy harvesting performance for the cymbal structure. The parameters such as thickness of the end caps, radius ratio of the apex to the cavity of the end caps, cavity depth, and thickness ratio of the piezoelectric to the steel substrate are considered. Based on the optimized dimension, a cymbal harvester was fabricated and tested to validate analytically predicted open-circuit voltage on a hand jack type test rig.
Experimental result indicates that the measured open-circuit voltage from the bimorph cymbal harvester is less than that of analytically predicted. However, it shows that the bimorph piezoelectric cymbal structure is an alternative cymbal design that is useful for harvesting energy from the source of relatively high load.