Broadband vibration energy harvesting under bidirectional frequency sweeps via contact nonlinearity and a trigger mechanism

Abstract

Sustainable power generation through vibration energy harvesting requires systems that can operate efficiently across a wide frequency spectrum. While nonlinear mechanisms are often integrated to expand the effective bandwidth, many existing designs suffer from performance degradation during downsweep frequency excitation because of the coexistence of multiple stable attractors. This study presents a nonlinear vibration energy harvesting configuration utilizing contact nonlinearity and a passive triggering mechanism to ensure broadband performance under bidirectional excitation. The system combines a primary mechanical oscillator and a piezoelectric transducer with a secondary trigger oscillator designed to induce high-amplitude oscillations under downsweep frequency excitation. A lumped-mass model was developed to analyze the system's dynamic behavior and was subsequently validated through experimental testing of a physical prototype. The results demonstrate that the proposed VEH system successfully maintains high vibration amplitudes during both upsweep and downsweep excitation, providing a robust framework for consistent energy harvesting in variable excitation environments. Furthermore, design guidelines are established for determining the key system parameters required to achieve the desired performance under different excitation levels and target operating frequency ranges.