Broadband low-frequency energy harvesting using graded metamaterial piezoelectric

This study presents the numerical design and optimization of a graded piezoelectric metamaterial for low-frequency and broadband piezoelectric energy harvesting applications. The proposed metamaterial structure consists of an aluminum host beam integrated with twenty local resonators, each comprising a steel core with an attached PZT-5H patch. The harvested power from surrounding wasted energy is utilized to power sensors in structural health monitoring applications. The design is numerically investigated using the Finite Element Method (FEM) in COMSOL, and the results are validated with experimental results from the literature. Several configurations are symmetrically investigated: the conventional periodic arrangement, assembled beams in the middle, complete graded resonators, cavity-enhanced complete graded configurations, and arrangements with additional piezoelectric patches on both the host and the resonators. The optimized configuration achieves a broadband frequency response of 0–400 Hz and a maximum harvested power of 0.42 mW, representing a 60-fold enhancement compared to the conventional design and a 22-fold improvement over fully graded configurations.