الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Power generation efficiency, of piezoelectric energy harvesters, depends upon selecting the suitable cantilever geometry and tuning its natural frequency with the vibration source frequency. Moreover, the effect of harvester parameters such as width, length, and total thickness of the cantilever beam on natural frequency is a vital step on tuning the resonance frequency. So, COMSOL Multi-physics, Eigen frequency study and analytical analysis using MATLAB were utilized to determine the resonance frequencies and to analyse the harvester parameters effect. The T-shaped, rectangular shaped, L-shaped, variable width, and triangular shaped cantilevers were studied, optimized and simulated. The five shapes were optimized using the optimization COMSOL module. The simulation of the five shapes was implemented using COMSOL. The results showed that T- shaped cantilever gives the largest power of 13 mW (1.38 times higher output power compared to triangle shape for the same volume). Due to its high power and comprehensive shape, the T-shaped cantilever with variable width was optimized using COMSOL optimization module (BOBYQA). The results of the BOBYQA optimization algorithm, employed in COMSOL, introduced high improvement in the output power and volt that were 183.2 mW and 9.6V respectively. Two case studies of engine vibration and car suspension energy harvesting were investigated to target the frequency of a vibrating source efficiently. The two optimization methodologies were GA and COMSOL optimization module. Then, a multi-physics COMSOL was utilized to simulate the results of the COMSOL optimization module and MATLAB was applied to simulate the results of the GA optimization methodology. The analytical simulation of GA and literature results were used to verify the COMSOL (FE simulation) results. The power per unit volume of the first case study using COMSOL (FEM) was 67.25×10-3 mW/mm3 versus 60.5×103 mW/mm3 for analytical (GA). While, the power per volume of the second case study, using COMSOL (FEM) was 93.8 ×10-3 mW/mm3, versus 81.5×10-3 mW/mm3 for analytical (GA). Also, studies of the stresses due to dynamic load were performed to avoid the failure. To verify the COMSOL (FE simulation) results, experimental setup of piezoelectric cantilevers was utilized. The experimental setup was used to calculate the voltage of the base excited harvester with very low frequencies from 0.5 to 10 Hz and 0.3 m/s2 amplitude. Also, the experimental setup was employed to study effects of the tip mass, length of the cantilever and piezoelectric material volume on the output voltage. To solve the power DROP problem due to the variation in excitation frequency, a harvester with concentrated masses was investigated. Four models were designed to prove that the harvester with concentrated masses can broaden the natural frequency. The four models were, harvester without mass (simple), harvester with three concentrated masses, harvester with six concentrated masses, and L-shaped harvester with three concentrated masses. The results prove that the increase for the bandwidth, of the six masses harvester, was about 52 % and about 10.1 % for the output power.