Vibration of multilayer cantilever beams towards piezoelectric power harvesters

Abstract

This paper investigates the vibration characteristics of a commonly employed mechanical structure, the cantilever beam, concerning its potential for direct electricity harvesting from piezoelectric crystals. Piezoelectric materials are renowned for their ability to generate electric charges when subjected to mechanical stress. To ensure continuous current generation, these materials require sustained excitation by external forces, typically achieved through vibration. However, piezoelectric crystals lack sufficient elasticity, necessitating attachment to a structurally conducive and easily vibratable framework. The cantilever beam, renowned for its simplicity and widespread use, serves as an ideal platform for this purpose. Layers of piezoelectric material (PZT5H) are affixed to brass-based cantilever beams to create various multilayer configurations. External forces are then applied at the free end of the beam to induce vibration. Given that the harvested power from PZT5H crystals correlates with the mechanical stress they experience, achieving optimal deformation is paramount. This is accomplished by leveraging the resonance effect of vibration, wherein the vibration modes and natural frequencies of the multilayer PZT5H beams must be thoroughly characterized. To this end, numerical methods and Finite Element Analysis via Abaqus software are employed. The vibrations of the brass base layer, as well as single-sided and double-sided PZT5H beams, are analyzed across four distinct mode shapes and corresponding natural frequencies. The study culminates in a comprehensive examination of the relationship between natural frequencies and dimensional parameters of the beams. Ultimately, this research offers valuable insights into the vibration behavior of cantilever beams, laying the groundwork for the development of efficient power harvesting devices utilizing mechanical vibration sources or tailored to specific applications.