Publication

Abstract : Practical bistable vibration energy harvesters (VEHs) rarely have a perfectly symmetric potential function: manufacturing imperfections and magnetic-field variations introduce asymmetry that suppresses inter-well motion and reduces the harvested power under low-amplitude excitation. Elastic magnifiers (EMs) have been used to enhance symmetric bistable VEHs, but their application to asymmetric configurations, together with experimental validation and global sensitivity analysis (GSA), has not previously been reported. This study proposes and validates an asymmetric bistable piezoelectric VEH integrated with an EM to enhance energy harvesting performance under low-amplitude excitation. The non-linear dynamics of the resulting two-degree-of-freedom system are investigated through analytical modelling, harmonic balance analysis, numerical simulation, and experiments on a fabricated prototype, and a polynomial chaos expansion (PCE)-based Sobol GSA is used to quantify the influence of six uncertain system parameters on the harvested power. The EM is found to promote large-amplitude inter-well oscillations, introduce two resonant peaks associated with the two-degree-of-freedom configuration, and substantially broaden the operating bandwidth relative to the asymmetric bistable VEH without an EM. Experiments confirm a 113% increase in the steady-state output voltage (from 1.50 V to 3.20 V), with the beam displacement and harvested voltage increasing by approximately threefold and twofold, respectively. The GSA identifies the electromechanical coupling coefficient ( κ ) as the most influential parameter, followed by the EM mass and stiffness ratios ( r m , r k ). Relative to symmetric bistable VEHs already enhanced with an EM, and to prior analytical/numerical studies of EM-augmented asymmetric bistable VEHs that lack experimental confirmation, the proposed design is shown, through the same experiments, to achieve broader bandwidth and higher harvested voltage while additionally providing the first experimental validation and an efficient, uncertainty-aware design framework for this configuration. These results demonstrate that combining an EM with an asymmetric bistable architecture, guided by a computationally efficient GSA framework, provides a practical and generalizable route to robust, high-performance vibration energy harvesting for self-powered sensing applications.