Modeling and experimental validation of unimorph piezoelectric cymbal design in energy harvesting

This article presents a unimorph lead zirconate titanate cymbal structure as an energy harvester. The unimorph lead zirconate titanate cymbal harvester was designed to be able to sustain higher mechanical loads by replacing the lead zirconate titanate monolayer with the lead zirconate titanate/steel composite between the metal end caps. Theoretical analysis was first carried out to predict energy-harvesting performance of the new cymbal design. A parametric study was also performed on two key geometric parameters to reveal trends that affect energy-generating performance for the cymbal structure. The dominant parameters that affect the performance are thickness of the metal end cap, the ratio of the radius of the apex to the radius of the cavity, and the thickness ratio of the lead zirconate titanate to the steel substrate. A specimen was then fabricated and tested on a load-frame to validate analytically predicted energy-scavenging performance. The specimen was tested under a 1-Hz cyclic load of up to 1940 N. The measured open-circuit output voltages for two different load inputs were close to the analytical results. The experimental results also indicate that the unimorph cymbal harvester can generate a power of 121.2 µW at 3.3 MΩ resistive load under 1-Hz cyclic load of 1940 N.