الفهرس 
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Abstract
Due to the ubiquity of vibration sources, vibration energy harvesting has become widespread. In this work, a multi-resonant vibration energy harvester for wideband energy harvesting over a frequency range of 10 Hz-15 Hz was designed and evaluated. The design comprises a cantilever beam with two parallel grooves to form three dissimilar parallel branches, each with an unequal length and a concentrated tip mass. The piezoelectric material covers the whole length on both sides of the beam to form a bimorph. Appropriate geometry and mass magnitudes were obtained by a parametric study using the Finite Element Method. The design was simulated in COMSOL Multiphysics to study its response. The simulation was conducted under a base acceleration of 0.2 g and a load impedance of 10 kΩ. The first three bending modes were utilized in energy harvesting, resulting in three power peaks at their respective fundamental frequencies. The adequate load resistance determined was 5.62 kΩ, at which maximum power can be harvested. The need to fully utilize the harvester’s capacity and provide essential power to the microelectronic devices for extended time periods aroused the need for optimization. BOBYQA algorithm was deployed because of its versatility in derivative-free, bound constrained optimization problems. The end mass magnitudes, and the lengths and thicknesses of the harvester materials (substrate and piezoelectric), were the optimizable variables. A 31.67% average power increment was realized. The optimal impedance was reduced from 5.62 kΩ to 1.778 kΩ. The reduced load resistance magnitude enhances efficiency by reducing electrical damping. The proposed harvester proved to be more efficient by harvesting sufficiently higher broadband energy and is applicable in a wide range of vibration environments. The efficiency is because of the harvester’s adaptability in design in both the optimized and un-optimized forms.