Exploiting internal resonance of 3D-printed weakly coupled structures for piezoelectric energy harvesting

This work presents a novel design based on weakly-coupled beam-based structural elements with engineered nonlinearities that hosts a piezoelectric thin film for energy harvesting. The H-shaped structure are finite elements simulated to understand their frequency response, which includes local and global mode interactions. The inherently nonlinear structures are then designed to enable the activation of the 1:1, 1:2, and 1:3 internal resonances that broadens the frequency response and increases its amplitude. The H-shaped beam-based structures are 3D printed and their dynamic behavior is experimentally investigated using LDV to get insights on how to integrate them with piezoelectric elements. The experimental power measured from individual patches of an H-shaped piezoelectric loaded structure is 5.26 µW, which is relatively less than the power of a piezoelectric loaded doubly-clamped beam (9.18 µW). This discrepancy primarily arises from differences in size between the two batches. However, by integrating the voltage outputs from both patches on the H-shaped coupled beam structure, a synergistic effect is achieved, yielding a combined power of 14.31 µW. This concentration is observed across a broader frequency spectrum, specifically ranging from 180 to 200 Hz, as compared to the single peak exhibited by the doubly-clamped beam. These findings highlight the exceptional potential of the H-shaped coupled-beam structure and emphasize their remarkable efficiency of the piezoelectric energy harvesting.