Analytical Modeling and Experimental Validation of a Cymbal-Structured Piezoelectric Stack Energy Harvester

Abstract

Abstract

This study presents an analytical model and experimental validation of a low-profile cymbal-structured piezoelectric energy harvester designed for high-load, low-frequency applications. The harvester consists of two metallic cymbal end caps, four lead zirconate titanate (PZT) stacks, and an outer retaining ring. Unlike conventional cymbal harvesters, in which deformation of the metallic end caps induces tensile loading in a monolithic, unimorph, or bimorph piezoelectric element, the proposed configuration converts an externally applied axial load into radial compressive forces acting on the PZT stacks. This arrangement exploits the substantially higher compressive strength of piezoelectric ceramics and eliminates the highly stressed structural bonding interface associated with unimorph and bimorph cymbal designs. Under the low-frequency loading considered here, a quasi-static analytical model is developed to relate the applied axial force to the radial compressive stress transmitted to each PZT stack and subsequently to the generated electrical voltage. The piezoelectric coefficient and dielectric property required by the model are determined experimentally for the PZT stacks used in the prototype. Model predictions are validated against previously reported measurements from a fabricated four-stack harvester subjected to cyclic loads of 800, 1,500, and 2,100 N at 1 Hz. The predicted open-circuit voltage agrees well with the experimental measurements over the investigated loading range. The model therefore provides a physics-based framework for interpreting the electromechanical response of the restructured cymbal harvester and for subsequent design optimization of compact piezoelectric energy harvesters subjected to high compressive loads.